@setfilename standards.info
@settitle GNU Coding Standards
@c UPDATE THIS DATE WHENEVER YOU MAKE CHANGES!
-@set lastupdate 24 July 1995
+@set lastupdate 18 January 1996
@c %**end of header
@ifinfo
@end format
@end ifinfo
+@c @setchapternewpage odd
@setchapternewpage off
+@c This is used by a cross ref in make-stds.texi
+@set CODESTD 1
+@iftex
+@set CHAPTER chapter
+@end iftex
+@ifinfo
+@set CHAPTER node
+@end ifinfo
+
@ifinfo
GNU Coding Standards
-Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
+Copyright (C) 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@page
@vskip 0pt plus 1filll
-Copyright @copyright{} 1992, 1993, 1994 Free Software Foundation, Inc.
+Copyright @copyright{} 1992, 1993, 1994,1995 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@menu
* Preface:: About the GNU Coding Standards
-* Reading Non-Free Code:: Referring to Proprietary Programs
-* Contributions:: Accepting Contributions
-* Change Logs:: Recording Changes
-* Compatibility:: Compatibility with Other Implementations
-* Makefile Conventions:: Makefile Conventions
-* Configuration:: How Configuration Should Work
-* Source Language:: Using Languages Other Than C
-* Formatting:: Formatting Your Source Code
-* Comments:: Commenting Your Work
-* Syntactic Conventions:: Clean Use of C Constructs
-* Names:: Naming Variables, Functions and Files
-* Using Extensions:: Using Non-standard Features
-* System Functions:: Portability and ``standard'' library functions
-* Semantics:: Program Behavior for All Programs
-* Errors:: Formatting Error Messages
-* Libraries:: Library Behavior
-* Portability:: Portability As It Applies to GNU
-* User Interfaces:: Standards for Command Line Interfaces
+* Intellectual Property:: Keeping Free Software Free
+* Design Advice:: General Program Design
+* Program Behavior:: Program Behavior for All Programs
+* Writing C:: Making The Best Use of C
* Documentation:: Documenting Programs
-* Releases:: Making Releases
+* Managing Releases:: The Release Process
@end menu
@node Preface
The GNU Coding Standards were written by Richard Stallman and other GNU
Project volunteers. Their purpose is to make the GNU system clean,
consistent, and easy to install. This document can also be read as a
-guide to write portable, robust and reliable programs. It focuses on
+guide to writing portable, robust and reliable programs. It focuses on
programs written in C, but many of the rules and principles are useful
even if you write in another programming language. The rules often
state reasons for writing in a certain way.
This release of the GNU Coding Standards was last updated
@value{lastupdate}.
+@node Intellectual Property
+@chapter Keeping Free Software Free
+
+This @value{CHAPTER} discusses how you can make sure that GNU software
+remains unencumbered.
+
+@menu
+* Reading Non-Free Code:: Referring to Proprietary Programs
+* Contributions:: Accepting Contributions
+@end menu
+
@node Reading Non-Free Code
-@chapter Referring to Proprietary Programs
+@section Referring to Proprietary Programs
Don't in any circumstances refer to Unix source code for or during
your work on GNU! (Or to any other proprietary programs.)
@node Contributions
-@chapter Accepting Contributions
+@section Accepting Contributions
If someone else sends you a piece of code to add to the program you are
working on, we need legal papers to use it---the same sort of legal
contribution.
This applies both before you release the program and afterward. If
-you receive diffs to fix a bug, and they make significant change, we
+you receive diffs to fix a bug, and they make significant changes, we
need legal papers for it.
You don't need papers for changes of a few lines here or there, since
which you use. For example, if you write a different solution to the
problem, you don't need to get papers.
-I know this is frustrating; it's frustrating for us as well. But if
+We know this is frustrating; it's frustrating for us as well. But if
you don't wait, you are going out on a limb---for example, what if the
contributor's employer won't sign a disclaimer? You might have to take
that code out again!
contributor. We could be very embarrassed in court some day as a
result.
-@node Change Logs
-@chapter Change Logs
-
-Keep a change log for each directory, describing the changes made to
-source files in that directory. The purpose of this is so that people
-investigating bugs in the future will know about the changes that
-might have introduced the bug. Often a new bug can be found by
-looking at what was recently changed. More importantly, change logs
-can help eliminate conceptual inconsistencies between different parts
-of a program; they can give you a history of how the conflicting
-concepts arose.
-
-Use the Emacs command @kbd{M-x add-change-log-entry} to start a new
-entry in the
-change log. An entry should have an asterisk, the name of the changed
-file, and then in parentheses the name of the changed functions,
-variables or whatever, followed by a colon. Then describe the changes
-you made to that function or variable.
-
-Separate unrelated entries with blank lines. When two entries
-represent parts of the same change, so that they work together, then
-don't put blank lines between them. Then you can omit the file name
-and the asterisk when successive entries are in the same file.
-
-Here are some examples:
-
-@example
-* register.el (insert-register): Return nil.
-(jump-to-register): Likewise.
-
-* sort.el (sort-subr): Return nil.
-
-* tex-mode.el (tex-bibtex-file, tex-file, tex-region):
-Restart the tex shell if process is gone or stopped.
-(tex-shell-running): New function.
-
-* expr.c (store_one_arg): Round size up for move_block_to_reg.
-(expand_call): Round up when emitting USE insns.
-* stmt.c (assign_parms): Round size up for move_block_from_reg.
-@end example
-
-It's important to name the changed function or variable in full. Don't
-abbreviate them; don't combine them. Subsequent maintainers will often
-search for a function name to find all the change log entries that
-pertain to it; if you abbreviate the name, they won't find it when they
-search. For example, some people are tempted to abbreviate groups of
-function names by writing @samp{* register.el
-(@{insert,jump-to@}-register)}; this is not a good idea, since searching
-for @code{jump-to-register} or @code{insert-register} would not find the
-entry.
-
-There's no need to describe the full purpose of the changes or how they
-work together. It is better to put such explanations in comments in the
-code. That's why just ``New function'' is enough; there is a comment
-with the function in the source to explain what it does.
-
-However, sometimes it is useful to write one line to describe the
-overall purpose of a large batch of changes.
-
-You can think of the change log as a conceptual ``undo list'' which
-explains how earlier versions were different from the current version.
-People can see the current version; they don't need the change log
-to tell them what is in it. What they want from a change log is a
-clear explanation of how the earlier version differed.
-
-When you change the calling sequence of a function in a simple
-fashion, and you change all the callers of the function, there is no
-need to make individual entries for all the callers. Just write in
-the entry for the function being called, ``All callers changed.''
+@node Design Advice
+@chapter General Program Design
-When you change just comments or doc strings, it is enough to write an
-entry for the file, without mentioning the functions. Write just,
-``Doc fix.'' There's no need to keep a change log for documentation
-files. This is because documentation is not susceptible to bugs that
-are hard to fix. Documentation does not consist of parts that must
-interact in a precisely engineered fashion; to correct an error, you
-need not know the history of the erroneous passage.
+This @value{CHAPTER} discusses some of the issues you should take into
+account when designing your program.
+@menu
+* Compatibility:: Compatibility with Other Implementations
+* Using Extensions:: Using Non-standard Features
+* Source Language:: Using Languages Other Than C
+* Portability:: Portability As It Applies to GNU
+@end menu
@node Compatibility
-@chapter Compatibility with Other Implementations
+@section Compatibility with Other Implementations
+@c ADR: What are the exceptions?
With certain exceptions, utility programs and libraries for GNU should
be upward compatible with those in Berkeley Unix, and upward compatible
with @sc{ANSI} C if @sc{ANSI} C specifies their behavior, and upward
modes for each of them.
@sc{ANSI} C and @sc{POSIX} prohibit many kinds of extensions. Feel
-free to make the extensions anyway, and include a @samp{--ansi} or
+free to make the extensions anyway, and include a @samp{--ansi},
+@samp{--posix}, or
@samp{--compatible} option to turn them off. However, if the extension
has a significant chance of breaking any real programs or scripts,
then it is not really upward compatible. Try to redesign its
When a feature is used only by users (not by programs or command
files), and it is done poorly in Unix, feel free to replace it
completely with something totally different and better. (For example,
-vi is replaced with Emacs.) But it is nice to offer a compatible
-feature as well. (There is a free vi clone, so we offer it.)
+@code{vi} is replaced with Emacs.) But it is nice to offer a compatible
+feature as well. (There is a free @code{vi} clone, so we offer it.)
Additional useful features not in Berkeley Unix are welcome.
Additional programs with no counterpart in Unix may be useful,
but our first priority is usually to duplicate what Unix already
has.
-@comment The makefile standards are in a separate file that is also
-@comment included by make.texinfo. Done by roland@gnu.ai.mit.edu on 1/6/93.
-@include make-stds.texi
-
-@node Configuration
-@chapter How Configuration Should Work
+@node Using Extensions
+@section Using Non-standard Features
-Each GNU distribution should come with a shell script named
-@code{configure}. This script is given arguments which describe the
-kind of machine and system you want to compile the program for.
+Many GNU facilities that already exist support a number of convenient
+extensions over the comparable Unix facilities. Whether to use these
+extensions in implementing your program is a difficult question.
-The @code{configure} script must record the configuration options so
-that they affect compilation.
+On the one hand, using the extensions can make a cleaner program.
+On the other hand, people will not be able to build the program
+unless the other GNU tools are available. This might cause the
+program to work on fewer kinds of machines.
-One way to do this is to make a link from a standard name such as
-@file{config.h} to the proper configuration file for the chosen system.
-If you use this technique, the distribution should @emph{not} contain a
-file named @file{config.h}. This is so that people won't be able to
-build the program without configuring it first.
+With some extensions, it might be easy to provide both alternatives.
+For example, you can define functions with a ``keyword'' @code{INLINE}
+and define that as a macro to expand into either @code{inline} or
+nothing, depending on the compiler.
-Another thing that @code{configure} can do is to edit the Makefile. If
-you do this, the distribution should @emph{not} contain a file named
-@file{Makefile}. Instead, include a file @file{Makefile.in} which
-contains the input used for editing. Once again, this is so that people
-won't be able to build the program without configuring it first.
+In general, perhaps it is best not to use the extensions if you can
+straightforwardly do without them, but to use the extensions if they
+are a big improvement.
-If @code{configure} does write the @file{Makefile}, then @file{Makefile}
-should have a target named @file{Makefile} which causes @code{configure}
-to be rerun, setting up the same configuration that was set up last
-time. The files that @code{configure} reads should be listed as
-dependencies of @file{Makefile}.
+An exception to this rule are the large, established programs (such as
+Emacs) which run on a great variety of systems. Such programs would
+be broken by use of GNU extensions.
-All the files which are output from the @code{configure} script should
-have comments at the beginning explaining that they were generated
-automatically using @code{configure}. This is so that users won't think
-of trying to edit them by hand.
+Another exception is for programs that are used as part of
+compilation: anything that must be compiled with other compilers in
+order to bootstrap the GNU compilation facilities. If these require
+the GNU compiler, then no one can compile them without having them
+installed already. That would be no good.
-The @code{configure} script should write a file named @file{config.status}
-which describes which configuration options were specified when the
-program was last configured. This file should be a shell script which,
-if run, will recreate the same configuration.
+Since most computer systems do not yet implement @sc{ANSI} C, using the
+@sc{ANSI} C features is effectively using a GNU extension, so the
+same considerations apply. (Except for @sc{ANSI} features that we
+discourage, such as trigraphs---don't ever use them.)
-The @code{configure} script should accept an option of the form
-@samp{--srcdir=@var{dirname}} to specify the directory where sources are found
-(if it is not the current directory). This makes it possible to build
-the program in a separate directory, so that the actual source directory
-is not modified.
+@node Source Language
+@section Using Languages Other Than C
-If the user does not specify @samp{--srcdir}, then @code{configure} should
-check both @file{.} and @file{..} to see if it can find the sources. If
-it finds the sources in one of these places, it should use them from
-there. Otherwise, it should report that it cannot find the sources, and
-should exit with nonzero status.
+Using a language other than C is like using a non-standard feature: it
+will cause trouble for users. Even if GCC supports the other language,
+users may find it inconvenient to have to install the compiler for that
+other language in order to build your program. So please write in C.
-Usually the easy way to support @samp{--srcdir} is by editing a
-definition of @code{VPATH} into the Makefile. Some rules may need to
-refer explicitly to the specified source directory. To make this
-possible, @code{configure} can add to the Makefile a variable named
-@code{srcdir} whose value is precisely the specified directory.
+There are three exceptions for this rule:
-The @code{configure} script should also take an argument which specifies the
-type of system to build the program for. This argument should look like
-this:
+@itemize @bullet
+@item
+It is okay to use a special language if the same program contains an
+interpreter for that language.
-@example
-@var{cpu}-@var{company}-@var{system}
-@end example
+Thus, it is not a problem that GNU Emacs contains code written in Emacs
+Lisp, because it comes with a Lisp interpreter.
-For example, a Sun 3 might be @samp{m68k-sun-sunos4.1}.
+@item
+It is okay to use another language in a tool specifically intended for
+use with that language.
-The @code{configure} script needs to be able to decode all plausible
-alternatives for how to describe a machine. Thus, @samp{sun3-sunos4.1}
-would be a valid alias. For many programs, @samp{vax-dec-ultrix} would
-be an alias for @samp{vax-dec-bsd}, simply because the differences
-between Ultrix and @sc{BSD} are rarely noticeable, but a few programs
-might need to distinguish them.
-@c Real 4.4BSD now runs on some Suns.
+This is okay because the only people who want to build the tool will be
+those who have installed the other language anyway.
-There is a shell script called @file{config.sub} that you can use
-as a subroutine to validate system types and canonicalize aliases.
+@item
+If an application is not of extremely widespread interest, then perhaps
+it's not important if the application is inconvenient to install.
+@end itemize
-Other options are permitted to specify in more detail the software
-or hardware present on the machine, and include or exclude optional
-parts of the package:
+@node Portability
+@section Portability As It Applies to GNU
-@table @samp
-@item --enable-@var{feature}@r{[}=@var{parameter}@r{]}
-Configure the package to build and install an optional user-level
-facility called @var{feature}. This allows users to choose which
-optional features to include. Giving an optional @var{parameter} of
-@samp{no} should omit @var{feature}, if it is built by default.
+Much of what is called ``portability'' in the Unix world refers to
+porting to different Unix versions. This is a secondary consideration
+for GNU software, because its primary purpose is to run on top of one
+and only one kernel, the GNU kernel, compiled with one and only one C
+compiler, the GNU C compiler. The amount and kinds of variation among
+GNU systems on different cpu's will be like the variation among Berkeley
+4.3 systems on different cpu's.
-No @samp{--enable} option should @strong{ever} cause one feature to
-replace another. No @samp{--enable} option should ever substitute one
-useful behavior for another useful behavior. The only proper use for
-@samp{--enable} is for questions of whether to build part of the program
-or exclude it.
+All users today run GNU software on non-GNU systems. So supporting a
+variety of non-GNU systems is desirable; simply not paramount.
+The easiest way to achieve portability to a reasonable range of systems
+is to use Autoconf. It's unlikely that your program needs to know more
+information about the host machine than Autoconf can provide, simply
+because most of the programs that need such knowledge have already been
+written.
-@item --with-@var{package}
-@c @r{[}=@var{parameter}@r{]}
-The package @var{package} will be installed, so configure this package
-to work with @var{package}.
+It is difficult to be sure exactly what facilities the GNU kernel
+will provide, since it isn't finished yet. Therefore, assume you can
+use anything in 4.3; just avoid using the format of semi-internal data
+bases (e.g., directories) when there is a higher-level alternative
+(@code{readdir}).
-@c Giving an optional @var{parameter} of
-@c @samp{no} should omit @var{package}, if it is used by default.
-
-Possible values of @var{package} include @samp{x}, @samp{x-toolkit},
-@samp{gnu-as} (or @samp{gas}), @samp{gnu-ld}, @samp{gnu-libc}, and
-@samp{gdb}.
-
-Do not use a @samp{--with} option to specify the file name to use to
-find certain files. That is outside the scope of what @samp{--with}
-options are for.
-
-@item --nfp
-The target machine has no floating point processor.
-
-@item --gas
-The target machine assembler is GAS, the GNU assembler.
-This is obsolete; users should use @samp{--with-gnu-as} instead.
-
-@item --x
-The target machine has the X Window System installed.
-This is obsolete; users should use @samp{--with-x} instead.
-@end table
-
-All @code{configure} scripts should accept all of these ``detail''
-options, whether or not they make any difference to the particular
-package at hand. In particular, they should accept any option that
-starts with @samp{--with-} or @samp{--enable-}. This is so users will
-be able to configure an entire GNU source tree at once with a single set
-of options.
-
-You will note that the categories @samp{--with-} and @samp{--enable-}
-are narrow: they @strong{do not} provide a place for any sort of option
-you might think of. That is deliberate. We want to limit the possible
-configuration options in GNU software. We do not want GNU programs to
-have idiosyncratic configuration options.
-
-Packages that perform part of compilation may support cross-compilation.
-In such a case, the host and target machines for the program may be
-different. The @code{configure} script should normally treat the
-specified type of system as both the host and the target, thus producing
-a program which works for the same type of machine that it runs on.
-
-The way to build a cross-compiler, cross-assembler, or what have you, is
-to specify the option @samp{--host=@var{hosttype}} when running
-@code{configure}. This specifies the host system without changing the
-type of target system. The syntax for @var{hosttype} is the same as
-described above.
-
-Bootstrapping a cross-compiler requires compiling it on a machine other
-than the host it will run on. Compilation packages accept a
-configuration option @samp{--build=@var{hosttype}} for specifying the
-configuration on which you will compile them, in case that is different
-from the host.
-
-Programs for which cross-operation is not meaningful need not accept the
-@samp{--host} option, because configuring an entire operating system for
-cross-operation is not a meaningful thing.
-
-Some programs have ways of configuring themselves automatically. If
-your program is set up to do this, your @code{configure} script can simply
-ignore most of its arguments.
-
-@node Source Language
-@chapter Using Languages Other Than C
-
-Using a language other than C is like using a non-standard feature: it
-will cause trouble for users. Even if GCC supports the other language,
-users may find it inconvenient to have to install the compiler for that
-other language in order to build your program. So please write in C.
-
-There are three exceptions for this rule:
-
-@itemize @bullet
-@item
-It is okay to use a special language if the same program contains an
-interpreter for that language.
-
-Thus, it is not a problem that GNU Emacs contains code written in Emacs
-Lisp, because it comes with a Lisp interpreter.
-
-@item
-It is okay to use another language in a tool specifically intended for
-use with that language.
-
-This is okay because the only people who want to build the tool will be
-those who have installed the other language anyway.
-
-@item
-If an application is not of extremely widespread interest, then perhaps
-it's not important if the application is inconvenient to install.
-@end itemize
-
-@node Formatting
-@chapter Formatting Your Source Code
-
-It is important to put the open-brace that starts the body of a C
-function in column zero, and avoid putting any other open-brace or
-open-parenthesis or open-bracket in column zero. Several tools look
-for open-braces in column zero to find the beginnings of C functions.
-These tools will not work on code not formatted that way.
-
-It is also important for function definitions to start the name of the
-function in column zero. This helps people to search for function
-definitions, and may also help certain tools recognize them. Thus,
-the proper format is this:
-
-@example
-static char *
-concat (s1, s2) /* Name starts in column zero here */
- char *s1, *s2;
-@{ /* Open brace in column zero here */
- @dots{}
-@}
-@end example
+You can freely assume any reasonably standard facilities in the C
+language, libraries or kernel, because we will find it necessary to
+support these facilities in the full GNU system, whether or not we
+have already done so. The fact that there may exist kernels or C
+compilers that lack these facilities is irrelevant as long as the GNU
+kernel and C compiler support them.
-@noindent
-or, if you want to use @sc{ANSI} C, format the definition like this:
+It remains necessary to worry about differences among cpu types, such
+as the difference in byte ordering and alignment restrictions. It's
+unlikely that 16-bit machines will ever be supported by GNU, so there
+is no point in spending any time to consider the possibility that an
+@code{int} will be less than 32 bits.
-@example
-static char *
-concat (char *s1, char *s2)
-@{
- @dots{}
-@}
-@end example
+You can assume that all pointers have the same format, regardless
+of the type they point to, and that this is really an integer.
+There are some weird machines where this isn't true, but they aren't
+important; don't waste time catering to them. Besides, eventually
+we will put function prototypes into all GNU programs, and that will
+probably make your program work even on weird machines.
-In @sc{ANSI} C, if the arguments don't fit nicely on one line,
-split it like this:
+Since some important machines (including the 68000) are big-endian,
+it is important not to assume that the address of an @code{int} object
+is also the address of its least-significant byte. Thus, don't
+make the following mistake:
@example
-int
-lots_of_args (int an_integer, long a_long, short a_short,
- double a_double, float a_float)
+int c;
@dots{}
+while ((c = getchar()) != EOF)
+ write(file_descriptor, &c, 1);
@end example
-For the body of the function, we prefer code formatted like this:
-
-@example
-if (x < foo (y, z))
- haha = bar[4] + 5;
-else
- @{
- while (z)
- @{
- haha += foo (z, z);
- z--;
- @}
- return ++x + bar ();
- @}
-@end example
-
-We find it easier to read a program when it has spaces before the
-open-parentheses and after the commas. Especially after the commas.
-
-When you split an expression into multiple lines, split it
-before an operator, not after one. Here is the right way:
-
-@example
-if (foo_this_is_long && bar > win (x, y, z)
- && remaining_condition)
-@end example
-
-Try to avoid having two operators of different precedence at the same
-level of indentation. For example, don't write this:
-
-@example
-mode = (inmode[j] == VOIDmode
- || GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j])
- ? outmode[j] : inmode[j]);
-@end example
-
-Instead, use extra parentheses so that the indentation shows the nesting:
-
-@example
-mode = ((inmode[j] == VOIDmode
- || (GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j])))
- ? outmode[j] : inmode[j]);
-@end example
+You can assume that it is reasonable to use a meg of memory. Don't
+strain to reduce memory usage unless it can get to that level. If
+your program creates complicated data structures, just make them in
+core and give a fatal error if @code{malloc} returns zero.
-Insert extra parentheses so that Emacs will indent the code properly.
-For example, the following indentation looks nice if you do it by hand,
-but Emacs would mess it up:
+If a program works by lines and could be applied to arbitrary
+user-supplied input files, it should keep only a line in memory, because
+this is not very hard and users will want to be able to operate on input
+files that are bigger than will fit in core all at once.
-@example
-v = rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
- + rup->ru_stime.tv_sec*1000 + rup->ru_stime.tv_usec/1000;
-@end example
+@node Program Behavior
+@chapter Program Behavior for All Programs
-But adding a set of parentheses solves the problem:
+This @value{CHAPTER} describes how to write robust software. It also
+describes general standards for error messages, the command line interface,
+and how libraries should behave.
-@example
-v = (rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
- + rup->ru_stime.tv_sec*1000 + rup->ru_stime.tv_usec/1000);
-@end example
+@menu
+* Semantics:: Writing Robust Programs
+* Libraries:: Library Behavior
+* Errors:: Formatting Error Messages
+* User Interfaces:: Standards for Command Line Interfaces
+@end menu
-Format do-while statements like this:
+@node Semantics
+@section Writing Robust Programs
-@example
-do
- @{
- a = foo (a);
- @}
-while (a > 0);
-@end example
+Avoid arbitrary limits on the length or number of @emph{any} data
+structure, including file names, lines, files, and symbols, by allocating
+all data structures dynamically. In most Unix utilities, ``long lines
+are silently truncated''. This is not acceptable in a GNU utility.
-Please use formfeed characters (control-L) to divide the program into
-pages at logical places (but not within a function). It does not matter
-just how long the pages are, since they do not have to fit on a printed
-page. The formfeeds should appear alone on lines by themselves.
+Utilities reading files should not drop NUL characters, or any other
+nonprinting characters @emph{including those with codes above 0177}. The
+only sensible exceptions would be utilities specifically intended for
+interface to certain types of printers that can't handle those characters.
+Check every system call for an error return, unless you know you wish to
+ignore errors. Include the system error text (from @code{perror} or
+equivalent) in @emph{every} error message resulting from a failing
+system call, as well as the name of the file if any and the name of the
+utility. Just ``cannot open foo.c'' or ``stat failed'' is not
+sufficient.
-@node Comments
-@chapter Commenting Your Work
+Check every call to @code{malloc} or @code{realloc} to see if it
+returned zero. Check @code{realloc} even if you are making the block
+smaller; in a system that rounds block sizes to a power of 2,
+@code{realloc} may get a different block if you ask for less space.
-Every program should start with a comment saying briefly what it is for.
-Example: @samp{fmt - filter for simple filling of text}.
+In Unix, @code{realloc} can destroy the storage block if it returns
+zero. GNU @code{realloc} does not have this bug: if it fails, the
+original block is unchanged. Feel free to assume the bug is fixed. If
+you wish to run your program on Unix, and wish to avoid lossage in this
+case, you can use the GNU @code{malloc}.
-Please put a comment on each function saying what the function does,
-what sorts of arguments it gets, and what the possible values of
-arguments mean and are used for. It is not necessary to duplicate in
-words the meaning of the C argument declarations, if a C type is being
-used in its customary fashion. If there is anything nonstandard about
-its use (such as an argument of type @code{char *} which is really the
-address of the second character of a string, not the first), or any
-possible values that would not work the way one would expect (such as,
-that strings containing newlines are not guaranteed to work), be sure
-to say so.
+You must expect @code{free} to alter the contents of the block that was
+freed. Anything you want to fetch from the block, you must fetch before
+calling @code{free}.
-Also explain the significance of the return value, if there is one.
+If @code{malloc} fails in a noninteractive program, make that a fatal
+error. In an interactive program (one that reads commands from the
+user), it is better to abort the command and return to the command
+reader loop. This allows the user to kill other processes to free up
+virtual memory, and then try the command again.
-Please put two spaces after the end of a sentence in your comments, so
-that the Emacs sentence commands will work. Also, please write
-complete sentences and capitalize the first word. If a lower-case
-identifier comes at the beginning of a sentence, don't capitalize it!
-Changing the spelling makes it a different identifier. If you don't
-like starting a sentence with a lower case letter, write the sentence
-differently (e.g., ``The identifier lower-case is @dots{}'').
+Use @code{getopt_long} to decode arguments, unless the argument syntax
+makes this unreasonable.
-The comment on a function is much clearer if you use the argument
-names to speak about the argument values. The variable name itself
-should be lower case, but write it in upper case when you are speaking
-about the value rather than the variable itself. Thus, ``the inode
-number NODE_NUM'' rather than ``an inode''.
+When static storage is to be written in during program execution, use
+explicit C code to initialize it. Reserve C initialized declarations
+for data that will not be changed.
+@c ADR: why?
-There is usually no purpose in restating the name of the function in
-the comment before it, because the reader can see that for himself.
-There might be an exception when the comment is so long that the function
-itself would be off the bottom of the screen.
+Try to avoid low-level interfaces to obscure Unix data structures (such
+as file directories, utmp, or the layout of kernel memory), since these
+are less likely to work compatibly. If you need to find all the files
+in a directory, use @code{readdir} or some other high-level interface.
+These will be supported compatibly by GNU.
-There should be a comment on each static variable as well, like this:
+By default, the GNU system will provide the signal handling functions of
+@sc{BSD} and of @sc{POSIX}. So GNU software should be written to use
+these.
-@example
-/* Nonzero means truncate lines in the display;
- zero means continue them. */
-int truncate_lines;
-@end example
+In error checks that detect ``impossible'' conditions, just abort.
+There is usually no point in printing any message. These checks
+indicate the existence of bugs. Whoever wants to fix the bugs will have
+to read the source code and run a debugger. So explain the problem with
+comments in the source. The relevant data will be in variables, which
+are easy to examine with the debugger, so there is no point moving them
+elsewhere.
-Every @samp{#endif} should have a comment, except in the case of short
-conditionals (just a few lines) that are not nested. The comment should
-state the condition of the conditional that is ending, @emph{including
-its sense}. @samp{#else} should have a comment describing the condition
-@emph{and sense} of the code that follows. For example:
+Do not use a count of errors as the exit status for a program.
+@emph{That does not work}, because exit status values are limited to 8
+bits (0 through 255). A single run of the program might have 256
+errors; if you try to return 256 as the exit status, the parent process
+will see 0 as the status, and it will appear that the program succeeded.
-@example
-#ifdef foo
- @dots{}
-#else /* not foo */
- @dots{}
-#endif /* not foo */
-@end example
+If you make temporary files, check the @code{TMPDIR} environment
+variable; if that variable is defined, use the specified directory
+instead of @file{/tmp}.
-@noindent
-but, by contrast, write the comments this way for a @samp{#ifndef}:
+@node Libraries
+@section Library Behavior
-@example
-#ifndef foo
- @dots{}
-#else /* foo */
- @dots{}
-#endif /* foo */
-@end example
+Try to make library functions reentrant. If they need to do dynamic
+storage allocation, at least try to avoid any nonreentrancy aside from
+that of @code{malloc} itself.
+Here are certain name conventions for libraries, to avoid name
+conflicts.
-@node Syntactic Conventions
-@chapter Clean Use of C Constructs
+Choose a name prefix for the library, more than two characters long.
+All external function and variable names should start with this
+prefix. In addition, there should only be one of these in any given
+library member. This usually means putting each one in a separate
+source file.
-Please explicitly declare all arguments to functions.
-Don't omit them just because they are @code{int}s.
+An exception can be made when two external symbols are always used
+together, so that no reasonable program could use one without the
+other; then they can both go in the same file.
-Declarations of external functions and functions to appear later in the
-source file should all go in one place near the beginning of the file
-(somewhere before the first function definition in the file), or else
-should go in a header file. Don't put @code{extern} declarations inside
-functions.
+External symbols that are not documented entry points for the user
+should have names beginning with @samp{_}. They should also contain
+the chosen name prefix for the library, to prevent collisions with
+other libraries. These can go in the same files with user entry
+points if you like.
-It used to be common practice to use the same local variables (with
-names like @code{tem}) over and over for different values within one
-function. Instead of doing this, it is better declare a separate local
-variable for each distinct purpose, and give it a name which is
-meaningful. This not only makes programs easier to understand, it also
-facilitates optimization by good compilers. You can also move the
-declaration of each local variable into the smallest scope that includes
-all its uses. This makes the program even cleaner.
+Static functions and variables can be used as you like and need not
+fit any naming convention.
-Don't use local variables or parameters that shadow global identifiers.
-Don't declare multiple variables in one declaration that spans lines.
-Start a new declaration on each line, instead. For example, instead
-of this:
+
+@node Errors
+@section Formatting Error Messages
+
+Error messages from compilers should look like this:
@example
-int foo,
- bar;
+@var{source-file-name}:@var{lineno}: @var{message}
@end example
-@noindent
-write either this:
+Error messages from other noninteractive programs should look like this:
@example
-int foo, bar;
+@var{program}:@var{source-file-name}:@var{lineno}: @var{message}
@end example
@noindent
-or this:
+when there is an appropriate source file, or like this:
@example
-int foo;
-int bar;
+@var{program}: @var{message}
@end example
@noindent
-(If they are global variables, each should have a comment preceding it
-anyway.)
+when there is no relevant source file.
-When you have an @code{if}-@code{else} statement nested in another
-@code{if} statement, always put braces around the @code{if}-@code{else}.
-Thus, never write like this:
+In an interactive program (one that is reading commands from a
+terminal), it is better not to include the program name in an error
+message. The place to indicate which program is running is in the
+prompt or with the screen layout. (When the same program runs with
+input from a source other than a terminal, it is not interactive and
+would do best to print error messages using the noninteractive style.)
-@example
-if (foo)
- if (bar)
- win ();
- else
- lose ();
-@end example
+The string @var{message} should not begin with a capital letter when
+it follows a program name and/or file name. Also, it should not end
+with a period.
-@noindent
-always like this:
+Error messages from interactive programs, and other messages such as
+usage messages, should start with a capital letter. But they should not
+end with a period.
-@example
-if (foo)
- @{
- if (bar)
- win ();
- else
- lose ();
- @}
-@end example
-If you have an @code{if} statement nested inside of an @code{else}
-statement, either write @code{else if} on one line, like this,
+@node User Interfaces
+@section Standards for Command Line Interfaces
-@example
-if (foo)
- @dots{}
-else if (bar)
- @dots{}
-@end example
+Please don't make the behavior of a utility depend on the name used
+to invoke it. It is useful sometimes to make a link to a utility
+with a different name, and that should not change what it does.
-@noindent
-with its @code{then}-part indented like the preceding @code{then}-part,
-or write the nested @code{if} within braces like this:
+Instead, use a run time option or a compilation switch or both
+to select among the alternate behaviors.
-@example
-if (foo)
- @dots{}
-else
- @{
- if (bar)
- @dots{}
- @}
-@end example
+Likewise, please don't make the behavior of the program depend on the
+type of output device it is used with. Device independence is an
+important principle of the system's design; do not compromise it
+merely to save someone from typing an option now and then.
-Don't declare both a structure tag and variables or typedefs in the
-same declaration. Instead, declare the structure tag separately
-and then use it to declare the variables or typedefs.
+If you think one behavior is most useful when the output is to a
+terminal, and another is most useful when the output is a file or a
+pipe, then it is usually best to make the default behavior the one that
+is useful with output to a terminal, and have an option for the other
+behavior.
-Try to avoid assignments inside @code{if}-conditions. For example,
-don't write this:
+Compatibility requires certain programs to depend on the type of output
+device. It would be disastrous if @code{ls} or @code{sh} did not do so
+in the way all users expect. In some of these cases, we supplement the
+program with a preferred alternate version that does not depend on the
+output device type. For example, we provide a @code{dir} program much
+like @code{ls} except that its default output format is always
+multi-column format.
-@example
-if ((foo = (char *) malloc (sizeof *foo)) == 0)
- fatal ("virtual memory exhausted");
-@end example
+It is a good idea to follow the @sc{POSIX} guidelines for the
+command-line options of a program. The easiest way to do this is to use
+@code{getopt} to parse them. Note that the GNU version of @code{getopt}
+will normally permit options anywhere among the arguments unless the
+special argument @samp{--} is used. This is not what @sc{POSIX}
+specifies; it is a GNU extension.
-@noindent
-instead, write this:
+Please define long-named options that are equivalent to the
+single-letter Unix-style options. We hope to make GNU more user
+friendly this way. This is easy to do with the GNU function
+@code{getopt_long}.
-@example
-foo = (char *) malloc (sizeof *foo);
-if (foo == 0)
- fatal ("virtual memory exhausted");
-@end example
+One of the advantages of long-named options is that they can be
+consistent from program to program. For example, users should be able
+to expect the ``verbose'' option of any GNU program which has one, to be
+spelled precisely @samp{--verbose}. To achieve this uniformity, look at
+the table of common long-option names when you choose the option names
+for your program. The table appears below.
-Don't make the program ugly to placate @code{lint}. Please don't insert any
-casts to @code{void}. Zero without a cast is perfectly fine as a null
-pointer constant.
+If you use names not already in the table, please send
+@samp{gnu@@prep.ai.mit.edu} a list of them, with their meanings, so we
+can update the table.
-@node Names
-@chapter Naming Variables, Functions, and Files
+It is usually a good idea for file names given as ordinary arguments
+to be input files only; any output files would be specified using
+options (preferably @samp{-o}). Even if you allow an output file name
+as an ordinary argument for compatibility, try to provide a suitable
+option as well. This will lead to more consistency among GNU
+utilities, so that there are fewer idiosyncracies for users to
+remember.
-Please use underscores to separate words in a name, so that the Emacs
-word commands can be useful within them. Stick to lower case; reserve
-upper case for macros and @code{enum} constants, and for name-prefixes
-that follow a uniform convention.
+Programs should support an option @samp{--version} which prints the
+program's version number on standard output and exits successfully, and
+an option @samp{--help} which prints option usage information on
+standard output and exits successfully. These options should inhibit
+the normal function of the command; they should do nothing except print
+the requested information.
-For example, you should use names like @code{ignore_space_change_flag};
-don't use names like @code{iCantReadThis}.
+@c Please leave newlines between items in this table; it's much easier
+@c to update when it isn't completely squashed together and unreadable.
+@c When there is more than one short option for a long option name, put
+@c a semicolon between the lists of the programs that use them, not a
+@c period. --friedman
-Variables that indicate whether command-line options have been
-specified should be named after the meaning of the option, not after
-the option-letter. A comment should state both the exact meaning of
-the option and its letter. For example,
+Here is the table of long options used by GNU programs.
-@example
-/* Ignore changes in horizontal whitespace (-b). */
-int ignore_space_change_flag;
-@end example
+@table @samp
-When you want to define names with constant integer values, use
-@code{enum} rather than @samp{#define}. GDB knows about enumeration
-constants.
+@item after-date
+@samp{-N} in @code{tar}.
-Use file names of 14 characters or less, to avoid creating gratuitous
-problems on System V. You can use the program @code{doschk} to test for
-this. @code{doschk} also tests for potential name conflicts if the
-files were loaded onto an MS-DOS file system---something you may or may
-not care about.
+@item all
+@samp{-a} in @code{du}, @code{ls}, @code{nm}, @code{stty}, @code{uname},
+and @code{unexpand}.
-In general, use @samp{-} to separate words in file names, not @samp{_}.
-Make all letters in file names be lower case, except when following
-specific conventions that call for upper case in certain kinds of names.
-Conventional occasions for using upper case letters in file names
-include @file{Makefile}, @file{ChangeLog}, @file{COPYING} and
-@file{README}. It is common to name other @file{README}-like
-documentation files in all upper case just like @file{README}.
+@item all-text
+@samp{-a} in @code{diff}.
-@node Using Extensions
-@chapter Using Non-standard Features
+@item almost-all
+@samp{-A} in @code{ls}.
-Many GNU facilities that already exist support a number of convenient
-extensions over the comparable Unix facilities. Whether to use these
-extensions in implementing your program is a difficult question.
+@item append
+@samp{-a} in @code{etags}, @code{tee}, @code{time};
+@samp{-r} in @code{tar}.
-On the one hand, using the extensions can make a cleaner program.
-On the other hand, people will not be able to build the program
-unless the other GNU tools are available. This might cause the
-program to work on fewer kinds of machines.
+@item archive
+@samp{-a} in @code{cp}.
-With some extensions, it might be easy to provide both alternatives.
-For example, you can define functions with a ``keyword'' @code{INLINE}
-and define that as a macro to expand into either @code{inline} or
-nothing, depending on the compiler.
+@item archive-name
+@samp{-n} in @code{shar}.
-In general, perhaps it is best not to use the extensions if you can
-straightforwardly do without them, but to use the extensions if they
-are a big improvement.
+@item arglength
+@samp{-l} in @code{m4}.
-An exception to this rule are the large, established programs (such as
-Emacs) which run on a great variety of systems. Such programs would
-be broken by use of GNU extensions.
+@item ascii
+@samp{-a} in @code{diff}.
-Another exception is for programs that are used as part of
-compilation: anything that must be compiled with other compilers in
-order to bootstrap the GNU compilation facilities. If these require
-the GNU compiler, then no one can compile them without having them
-installed already. That would be no good.
+@item assign
+@samp{-v} in @code{gawk}.
-Since most computer systems do not yet implement @sc{ANSI} C, using the
-@sc{ANSI} C features is effectively using a GNU extension, so the
-same considerations apply. (Except for @sc{ANSI} features that we
-discourage, such as trigraphs---don't ever use them.)
+@item assume-new
+@samp{-W} in Make.
+@item assume-old
+@samp{-o} in Make.
-@node System Functions
-@chapter Calling System Functions
+@item auto-check
+@samp{-a} in @code{recode}.
-C implementations differ substantially. ANSI C reduces but does not
-eliminate the incompatibilities; meanwhile, many users wish to compile
-GNU software with pre-ANSI compilers. This chapter gives
-recommendations for how to use the more or less standard C library
-functions to avoid unnecessary loss of portability.
+@item auto-pager
+@samp{-a} in @code{wdiff}.
-@itemize @bullet
-@item
-Don't use the value of @code{sprintf}. It returns the number of
-characters written on some systems, but not on all systems.
+@item auto-reference
+@samp{-A} in @code{ptx}.
-@item
-Don't declare system functions explicitly.
+@item avoid-wraps
+@samp{-n} in @code{wdiff}.
-Almost any declaration for a system function is wrong on some system.
-To minimize conflicts, leave it to the system header files to declare
-system functions. If the headers don't declare a function, let it
-remain undeclared.
+@item backward-search
+@samp{-B} in @code{ctags}.
-While it may seem unclean to use a function without declaring it, in
-practice this works fine for most system library functions on the
-systems where this really happens. The problem is only theoretical. By
-contrast, actual declarations have frequently caused actual conflicts.
+@item basename
+@samp{-f} in @code{shar}.
-@item
-If you must declare a system function, don't specify the argument types.
-Use an old-style declaration, not an ANSI prototype. The more you
-specify about the function, the more likely a conflict.
+@item batch
+Used in GDB.
-@item
-In particular, don't unconditionally declare @code{malloc} or
-@code{realloc}.
+@item baud
+Used in GDB.
-Most GNU programs use those functions just once, in functions
-conventionally named @code{xmalloc} and @code{xrealloc}. These
-functions call @code{malloc} and @code{realloc}, respectively, and
-check the results.
+@item before
+@samp{-b} in @code{tac}.
-Because @code{xmalloc} and @code{xrealloc} are defined in your program,
-you can declare them in other files without any risk of type conflict.
+@item binary
+@samp{-b} in @code{cpio} and @code{diff}.
-On most systems, @code{int} is the same length as a pointer; thus, the
-calls to @code{malloc} and @code{realloc} work fine. For the few
-exceptional systems (mostly 64-bit machines), you can use
-@strong{conditionalized} declarations of @code{malloc} and
-@code{realloc}---or put these declarations in configuration files
-specific to those systems.
+@item bits-per-code
+@samp{-b} in @code{shar}.
-@item
-The string functions require special treatment. Some Unix systems have
-a header file @file{string.h}; other have @file{strings.h}. Neither
-file name is portable. There are two things you can do: use Autoconf to
-figure out which file to include, or don't include either file.
+@item block-size
+Used in @code{cpio} and @code{tar}.
-@item
-If you don't include either strings file, you can't get declarations for
-the string functions from the header file in the usual way.
+@item blocks
+@samp{-b} in @code{head} and @code{tail}.
-That causes less of a problem than you might think. The newer ANSI
-string functions are off-limits anyway because many systems still don't
-support them. The string functions you can use are these:
+@item break-file
+@samp{-b} in @code{ptx}.
-@example
-strcpy strncpy strcat strncat
-strlen strcmp strncmp
-strchr strrchr
-@end example
+@item brief
+Used in various programs to make output shorter.
-The copy and concatenate functions work fine without a declaration as
-long as you don't use their values. Using their values without a
-declaration fails on systems where the width of a pointer differs from
-the width of @code{int}, and perhaps in other cases. It is trivial to
-avoid using their values, so do that.
+@item bytes
+@samp{-c} in @code{head}, @code{split}, and @code{tail}.
-The compare functions and @code{strlen} work fine without a declaration
-on most systems, possibly all the ones that GNU software runs on.
-You may find it necessary to declare them @strong{conditionally} on a
-few systems.
+@item c@t{++}
+@samp{-C} in @code{etags}.
-The search functions must be declared to return @code{char *}. Luckily,
-there is no variation in the data type they return. But there is
-variation in their names. Some systems give these functions the names
-@code{index} and @code{rindex}; other systems use the names
-@code{strchr} and @code{strrchr}. Some systems support both pairs of
-names, but neither pair works on all systems.
+@item catenate
+@samp{-A} in @code{tar}.
-You should pick a single pair of names and use it throughout your
-program. (Nowadays, it is better to choose @code{strchr} and
-@code{strrchr}.) Declare both of those names as functions returning
-@code{char *}. On systems which don't support those names, define them
-as macros in terms of the other pair. For example, here is what to put
-at the beginning of your file (or in a header) if you want to use the
-names @code{strchr} and @code{strrchr} throughout:
+@item cd
+Used in various programs to specify the directory to use.
-@example
-#ifndef HAVE_STRCHR
-#define strchr index
-#endif
-#ifndef HAVE_STRRCHR
-#define strrchr rindex
-#endif
+@item changes
+@samp{-c} in @code{chgrp} and @code{chown}.
-char *strchr ();
-char *strrchr ();
-@end example
-@end itemize
+@item classify
+@samp{-F} in @code{ls}.
-Here we assume that @code{HAVE_STRCHR} and @code{HAVE_STRRCHR} are
-macros defined in systems where the corresponding functions exist.
-One way to get them properly defined is to use Autoconf.
+@item colons
+@samp{-c} in @code{recode}.
-@node Semantics
-@chapter Program Behavior for All Programs
+@item command
+@samp{-c} in @code{su};
+@samp{-x} in GDB.
-Avoid arbitrary limits on the length or number of @emph{any} data
-structure, including file names, lines, files, and symbols, by allocating
-all data structures dynamically. In most Unix utilities, ``long lines
-are silently truncated''. This is not acceptable in a GNU utility.
+@item compare
+@samp{-d} in @code{tar}.
-Utilities reading files should not drop NUL characters, or any other
-nonprinting characters @emph{including those with codes above 0177}. The
-only sensible exceptions would be utilities specifically intended for
-interface to certain types of printers that can't handle those characters.
+@item compat
+Used in @code{gawk}.
-Check every system call for an error return, unless you know you wish to
-ignore errors. Include the system error text (from @code{perror} or
-equivalent) in @emph{every} error message resulting from a failing
-system call, as well as the name of the file if any and the name of the
-utility. Just ``cannot open foo.c'' or ``stat failed'' is not
-sufficient.
+@item compress
+@samp{-Z} in @code{tar} and @code{shar}.
-Check every call to @code{malloc} or @code{realloc} to see if it
-returned zero. Check @code{realloc} even if you are making the block
-smaller; in a system that rounds block sizes to a power of 2,
-@code{realloc} may get a different block if you ask for less space.
+@item concatenate
+@samp{-A} in @code{tar}.
-In Unix, @code{realloc} can destroy the storage block if it returns
-zero. GNU @code{realloc} does not have this bug: if it fails, the
-original block is unchanged. Feel free to assume the bug is fixed. If
-you wish to run your program on Unix, and wish to avoid lossage in this
-case, you can use the GNU @code{malloc}.
+@item confirmation
+@samp{-w} in @code{tar}.
-You must expect @code{free} to alter the contents of the block that was
-freed. Anything you want to fetch from the block, you must fetch before
-calling @code{free}.
+@item context
+Used in @code{diff}.
-If @code{malloc} fails in a noninteractive program, make that a fatal
-error. In an interactive program (one that reads commands from the
-user), it is better to abort the command and return to the command
-reader loop. This allows the user to kill other processes to free up
-virtual memory, and then try the command again.
+@item copyleft
+@samp{-W copyleft} in @code{gawk}.
-Use @code{getopt_long} to decode arguments, unless the argument syntax
-makes this unreasonable.
+@item copyright
+@samp{-C} in @code{ptx}, @code{recode}, and @code{wdiff};
+@samp{-W copyright} in @code{gawk}.
-When static storage is to be written in during program execution, use
-explicit C code to initialize it. Reserve C initialized declarations
-for data that will not be changed.
+@item core
+Used in GDB.
-Try to avoid low-level interfaces to obscure Unix data structures (such
-as file directories, utmp, or the layout of kernel memory), since these
-are less likely to work compatibly. If you need to find all the files
-in a directory, use @code{readdir} or some other high-level interface.
-These will be supported compatibly by GNU.
+@item count
+@samp{-q} in @code{who}.
-By default, the GNU system will provide the signal handling functions of
-@sc{BSD} and of @sc{POSIX}. So GNU software should be written to use
-these.
+@item count-links
+@samp{-l} in @code{du}.
-In error checks that detect ``impossible'' conditions, just abort.
-There is usually no point in printing any message. These checks
-indicate the existence of bugs. Whoever wants to fix the bugs will have
-to read the source code and run a debugger. So explain the problem with
-comments in the source. The relevant data will be in variables, which
-are easy to examine with the debugger, so there is no point moving them
-elsewhere.
+@item create
+Used in @code{tar} and @code{cpio}.
-Do not use a count of errors as the exit status for a program.
-@emph{That does not work}, because exit status values are limited to 8
-bits (0 through 255). A single run of the program might have 256
-errors; if you try to return 256 as the exit status, the parent process
-will see 0 as the status, and it will appear that the program succeeded.
+@item cut-mark
+@samp{-c} in @code{shar}.
-If you make temporary files, check the @code{TMPDIR} environment
-variable; if that variable is defined, use the specified directory
-instead of @file{/tmp}.
+@item cxref
+@samp{-x} in @code{ctags}.
-@node Errors
-@chapter Formatting Error Messages
+@item date
+@samp{-d} in @code{touch}.
-Error messages from compilers should look like this:
+@item debug
+@samp{-d} in Make and @code{m4};
+@samp{-t} in Bison.
-@example
-@var{source-file-name}:@var{lineno}: @var{message}
-@end example
+@item define
+@samp{-D} in @code{m4}.
-Error messages from other noninteractive programs should look like this:
+@item defines
+@samp{-d} in Bison and @code{ctags}.
-@example
-@var{program}:@var{source-file-name}:@var{lineno}: @var{message}
-@end example
+@item delete
+@samp{-D} in @code{tar}.
-@noindent
-when there is an appropriate source file, or like this:
+@item dereference
+@samp{-L} in @code{chgrp}, @code{chown}, @code{cpio}, @code{du},
+@code{ls}, and @code{tar}.
-@example
-@var{program}: @var{message}
-@end example
+@item dereference-args
+@samp{-D} in @code{du}.
-@noindent
-when there is no relevant source file.
+@item diacritics
+@samp{-d} in @code{recode}.
-In an interactive program (one that is reading commands from a
-terminal), it is better not to include the program name in an error
-message. The place to indicate which program is running is in the
-prompt or with the screen layout. (When the same program runs with
-input from a source other than a terminal, it is not interactive and
-would do best to print error messages using the noninteractive style.)
+@item dictionary-order
+@samp{-d} in @code{look}.
-The string @var{message} should not begin with a capital letter when
-it follows a program name and/or file name. Also, it should not end
-with a period.
+@item diff
+@samp{-d} in @code{tar}.
-Error messages from interactive programs, and other messages such as
-usage messages, should start with a capital letter. But they should not
-end with a period.
+@item digits
+@samp{-n} in @code{csplit}.
+@item directory
+Specify the directory to use, in various programs. In @code{ls}, it
+means to show directories themselves rather than their contents. In
+@code{rm} and @code{ln}, it means to not treat links to directories
+specially.
-@node Libraries
-@chapter Library Behavior
+@item discard-all
+@samp{-x} in @code{strip}.
-Try to make library functions reentrant. If they need to do dynamic
-storage allocation, at least try to avoid any nonreentrancy aside from
-that of @code{malloc} itself.
+@item discard-locals
+@samp{-X} in @code{strip}.
-Here are certain name conventions for libraries, to avoid name
-conflicts.
+@item dry-run
+@samp{-n} in Make.
-Choose a name prefix for the library, more than two characters long.
-All external function and variable names should start with this
-prefix. In addition, there should only be one of these in any given
-library member. This usually means putting each one in a separate
-source file.
+@item ed
+@samp{-e} in @code{diff}.
-An exception can be made when two external symbols are always used
-together, so that no reasonable program could use one without the
-other; then they can both go in the same file.
+@item elide-empty-files
+@samp{-z} in @code{csplit}.
-External symbols that are not documented entry points for the user
-should have names beginning with @samp{_}. They should also contain
-the chosen name prefix for the library, to prevent collisions with
-other libraries. These can go in the same files with user entry
-points if you like.
+@item end-delete
+@samp{-x} in @code{wdiff}.
-Static functions and variables can be used as you like and need not
-fit any naming convention.
+@item end-insert
+@samp{-z} in @code{wdiff}.
+@item entire-new-file
+@samp{-N} in @code{diff}.
-@node Portability
-@chapter Portability As It Applies to GNU
+@item environment-overrides
+@samp{-e} in Make.
-Much of what is called ``portability'' in the Unix world refers to
-porting to different Unix versions. This is a secondary consideration
-for GNU software, because its primary purpose is to run on top of one
-and only one kernel, the GNU kernel, compiled with one and only one C
-compiler, the GNU C compiler. The amount and kinds of variation among
-GNU systems on different cpu's will be like the variation among Berkeley
-4.3 systems on different cpu's.
+@item eof
+@samp{-e} in @code{xargs}.
-All users today run GNU software on non-GNU systems. So supporting a
-variety of non-GNU systems is desirable; simply not paramount.
-The easiest way to achieve portability to a reasonable range of systems
-is to use Autoconf. It's unlikely that your program needs to know more
-information about the host machine than Autoconf can provide, simply
-because most of the programs that need such knowledge have already been
-written.
+@item epoch
+Used in GDB.
-It is difficult to be sure exactly what facilities the GNU kernel
-will provide, since it isn't finished yet. Therefore, assume you can
-use anything in 4.3; just avoid using the format of semi-internal data
-bases (e.g., directories) when there is a higher-level alternative
-(@code{readdir}).
+@item error-limit
+Used in @code{makeinfo}.
-You can freely assume any reasonably standard facilities in the C
-language, libraries or kernel, because we will find it necessary to
-support these facilities in the full GNU system, whether or not we
-have already done so. The fact that there may exist kernels or C
-compilers that lack these facilities is irrelevant as long as the GNU
-kernel and C compiler support them.
+@item error-output
+@samp{-o} in @code{m4}.
-It remains necessary to worry about differences among cpu types, such
-as the difference in byte ordering and alignment restrictions. It's
-unlikely that 16-bit machines will ever be supported by GNU, so there
-is no point in spending any time to consider the possibility that an
-int will be less than 32 bits.
+@item escape
+@samp{-b} in @code{ls}.
-You can assume that all pointers have the same format, regardless
-of the type they point to, and that this is really an integer.
-There are some weird machines where this isn't true, but they aren't
-important; don't waste time catering to them. Besides, eventually
-we will put function prototypes into all GNU programs, and that will
-probably make your program work even on weird machines.
+@item exclude-from
+@samp{-X} in @code{tar}.
-Since some important machines (including the 68000) are big-endian,
-it is important not to assume that the address of an @code{int} object
-is also the address of its least-significant byte. Thus, don't
-make the following mistake:
+@item exec
+Used in GDB.
-@example
-int c;
-@dots{}
-while ((c = getchar()) != EOF)
- write(file_descriptor, &c, 1);
-@end example
+@item exit
+@samp{-x} in @code{xargs}.
-You can assume that it is reasonable to use a meg of memory. Don't
-strain to reduce memory usage unless it can get to that level. If
-your program creates complicated data structures, just make them in
-core and give a fatal error if malloc returns zero.
+@item exit-0
+@samp{-e} in @code{unshar}.
-If a program works by lines and could be applied to arbitrary
-user-supplied input files, it should keep only a line in memory, because
-this is not very hard and users will want to be able to operate on input
-files that are bigger than will fit in core all at once.
+@item expand-tabs
+@samp{-t} in @code{diff}.
+@item expression
+@samp{-e} in @code{sed}.
-@node User Interfaces
-@chapter Standards for Command Line Interfaces
+@item extern-only
+@samp{-g} in @code{nm}.
-Please don't make the behavior of a utility depend on the name used
-to invoke it. It is useful sometimes to make a link to a utility
-with a different name, and that should not change what it does.
+@item extract
+@samp{-i} in @code{cpio};
+@samp{-x} in @code{tar}.
-Instead, use a run time option or a compilation switch or both
-to select among the alternate behaviors.
+@item faces
+@samp{-f} in @code{finger}.
-Likewise, please don't make the behavior of the program depend on the
-type of output device it is used with. Device independence is an
-important principle of the system's design; do not compromise it
-merely to save someone from typing an option now and then.
+@item fast
+@samp{-f} in @code{su}.
-If you think one behavior is most useful when the output is to a
-terminal, and another is most useful when the output is a file or a
-pipe, then it is usually best to make the default behavior the one that
-is useful with output to a terminal, and have an option for the other
-behavior.
+@item fatal-warnings
+@samp{-E} in @code{m4}.
-Compatibility requires certain programs to depend on the type of output
-device. It would be disastrous if @code{ls} or @code{sh} did not do so
-in the way all users expect. In some of these cases, we supplement the
-program with a preferred alternate version that does not depend on the
-output device type. For example, we provide a @code{dir} program much
-like @code{ls} except that its default output format is always
-multi-column format.
+@item file
+@samp{-f} in @code{info}, @code{gawk}, Make, @code{mt}, and @code{tar};
+@samp{-n} in @code{sed};
+@samp{-r} in @code{touch}.
-It is a good idea to follow the @sc{POSIX} guidelines for the
-command-line options of a program. The easiest way to do this is to use
-@code{getopt} to parse them. Note that the GNU version of @code{getopt}
-will normally permit options anywhere among the arguments unless the
-special argument @samp{--} is used. This is not what @sc{POSIX}
-specifies; it is a GNU extension.
+@item field-separator
+@samp{-F} in @code{gawk}.
-Please define long-named options that are equivalent to the
-single-letter Unix-style options. We hope to make GNU more user
-friendly this way. This is easy to do with the GNU function
-@code{getopt_long}.
+@item file-prefix
+@samp{-b} in Bison.
-One of the advantages of long-named options is that they can be
-consistent from program to program. For example, users should be able
-to expect the ``verbose'' option of any GNU program which has one, to be
-spelled precisely @samp{--verbose}. To achieve this uniformity, look at
-the table of common long-option names when you choose the option names
-for your program. The table appears below.
+@item file-type
+@samp{-F} in @code{ls}.
-If you use names not already in the table, please send
-@samp{gnu@@prep.ai.mit.edu} a list of them, with their meanings, so we
-can update the table.
+@item files-from
+@samp{-T} in @code{tar}.
-It is usually a good idea for file names given as ordinary arguments
-to be input files only; any output files would be specified using
-options (preferably @samp{-o}). Even if you allow an output file name
-as an ordinary argument for compatibility, try to provide a suitable
-option as well. This will lead to more consistency among GNU
-utilities, so that there are fewer idiosyncracies for users to
-remember.
+@item fill-column
+Used in @code{makeinfo}.
-Programs should support an option @samp{--version} which prints the
-program's version number on standard output and exits successfully, and
-an option @samp{--help} which prints option usage information on
-standard output and exits successfully. These options should inhibit
-the normal function of the command; they should do nothing except print
-the requested information.
+@item flag-truncation
+@samp{-F} in @code{ptx}.
-@c longopts begin here (keyword for isearch)
-@c Please leave newlines between items in this table; it's much easier
-@c to update when it isn't completely squashed together and unreadable.
-@c When there is more than one short option for a long option name, put
-@c a semicolon between the lists of the programs that use them, not a
-@c period. --friedman
+@item fixed-output-files
+@samp{-y} in Bison.
-@table @samp
+@item follow
+@samp{-f} in @code{tail}.
-@item after-date
-@samp{-N} in @code{tar}.
+@item footnote-style
+Used in @code{makeinfo}.
-@item all
-@samp{-a} in @code{du}, @code{ls}, @code{nm}, @code{stty}, @code{uname},
-and @code{unexpand}.
+@item force
+@samp{-f} in @code{cp}, @code{ln}, @code{mv}, and @code{rm}.
-@item all-text
-@samp{-a} in @code{diff}.
+@item force-prefix
+@samp{-F} in @code{shar}.
-@item almost-all
-@samp{-A} in @code{ls}.
+@item format
+Used in @code{ls}, @code{time}, and @code{ptx}.
-@item append
-@samp{-a} in @code{etags}, @code{tee}, @code{time};
-@samp{-r} in @code{tar}.
+@item freeze-state
+@samp{-F} in @code{m4}.
+
+@item fullname
+Used in GDB.
-@item archive
-@samp{-a} in @code{cp}.
+@item gap-size
+@samp{-g} in @code{ptx}.
-@item archive-name
-@samp{-n} in @code{shar}.
+@item get
+@samp{-x} in @code{tar}.
-@item arglength
-@samp{-l} in @code{m4}.
+@item graphic
+@samp{-i} in @code{ul}.
-@item ascii
-@samp{-a} in @code{diff}.
+@item graphics
+@samp{-g} in @code{recode}.
-@item assign
-@samp{-v} in Gawk.
+@item group
+@samp{-g} in @code{install}.
-@item assume-new
-@samp{-W} in Make.
+@item gzip
+@samp{-z} in @code{tar} and @code{shar}.
-@item assume-old
-@samp{-o} in Make.
+@item hashsize
+@samp{-H} in @code{m4}.
-@item auto-check
-@samp{-a} in @code{recode}.
+@item header
+@samp{-h} in @code{objdump} and @code{recode}
-@item auto-pager
-@samp{-a} in @code{wdiff}.
+@item heading
+@samp{-H} in @code{who}.
-@item auto-reference
-@samp{-A} in @code{ptx}.
+@item help
+Used to ask for brief usage information.
-@item avoid-wraps
-@samp{-n} in @code{wdiff}.
+@item here-delimiter
+@samp{-d} in @code{shar}.
-@item backward-search
-@samp{-B} in @code{ctags}.
+@item hide-control-chars
+@samp{-q} in @code{ls}.
-@item basename
-@samp{-f} in @code{shar}.
+@item idle
+@samp{-u} in @code{who}.
-@item batch
-Used in GDB.
+@item ifdef
+@samp{-D} in @code{diff}.
-@item baud
-Used in GDB.
+@item ignore
+@samp{-I} in @code{ls};
+@samp{-x} in @code{recode}.
-@item before
-@samp{-b} in @code{tac}.
+@item ignore-all-space
+@samp{-w} in @code{diff}.
-@item binary
-@samp{-b} in @code{cpio} and @code{diff}.
+@item ignore-backups
+@samp{-B} in @code{ls}.
-@item bits-per-code
-@samp{-b} in @code{shar}.
+@item ignore-blank-lines
+@samp{-B} in @code{diff}.
-@item block-size
-Used in @code{cpio} and @code{tar}.
+@item ignore-case
+@samp{-f} in @code{look} and @code{ptx};
+@samp{-i} in @code{diff} and @code{wdiff}.
-@item blocks
-@samp{-b} in @code{head} and @code{tail}.
+@item ignore-errors
+@samp{-i} in Make.
-@item break-file
-@samp{-b} in @code{ptx}.
+@item ignore-file
+@samp{-i} in @code{ptx}.
-@item brief
-Used in various programs to make output shorter.
+@item ignore-indentation
+@samp{-I} in @code{etags}.
-@item bytes
-@samp{-c} in @code{head}, @code{split}, and @code{tail}.
+@item ignore-init-file
+@samp{-f} in Oleo.
-@item c@t{++}
-@samp{-C} in @code{etags}.
+@item ignore-interrupts
+@samp{-i} in @code{tee}.
-@item catenate
-@samp{-A} in @code{tar}.
+@item ignore-matching-lines
+@samp{-I} in @code{diff}.
-@item cd
-Used in various programs to specify the directory to use.
+@item ignore-space-change
+@samp{-b} in @code{diff}.
-@item changes
-@samp{-c} in @code{chgrp} and @code{chown}.
+@item ignore-zeros
+@samp{-i} in @code{tar}.
-@item classify
-@samp{-F} in @code{ls}.
+@item include
+@samp{-i} in @code{etags};
+@samp{-I} in @code{m4}.
-@item colons
-@samp{-c} in @code{recode}.
+@item include-dir
+@samp{-I} in Make.
-@item command
-@samp{-c} in @code{su};
-@samp{-x} in GDB.
+@item incremental
+@samp{-G} in @code{tar}.
-@item compare
-@samp{-d} in @code{tar}.
+@item info
+@samp{-i}, @samp{-l}, and @samp{-m} in Finger.
-@item compat
-Used in gawk (no corresponding single-letter option).
+@item initial
+@samp{-i} in @code{expand}.
-@item compress
-@samp{-Z} in @code{tar} and @code{shar}.
+@item initial-tab
+@samp{-T} in @code{diff}.
-@item concatenate
-@samp{-A} in @code{tar}.
+@item inode
+@samp{-i} in @code{ls}.
-@item confirmation
+@item interactive
+@samp{-i} in @code{cp}, @code{ln}, @code{mv}, @code{rm};
+@samp{-e} in @code{m4};
+@samp{-p} in @code{xargs};
@samp{-w} in @code{tar}.
-@item context
-Used in @code{diff}.
+@item intermix-type
+@samp{-p} in @code{shar}.
-@item copyleft
-Used in gawk (no corresponding single-letter option).
+@item jobs
+@samp{-j} in Make.
-@item copyright
-@samp{-C} in @code{ptx}, @code{recode}, and @code{wdiff}.
-Also used in gawk (no corresponding single-letter option).
+@item just-print
+@samp{-n} in Make.
-@item core
-Used in GDB.
+@item keep-going
+@samp{-k} in Make.
-@item count
-@samp{-q} in @code{who}.
+@item keep-files
+@samp{-k} in @code{csplit}.
-@item count-links
-@samp{-l} in @code{du}.
+@item kilobytes
+@samp{-k} in @code{du} and @code{ls}.
-@item create
-Used in @code{tar} and @code{cpio}.
+@item language
+@samp{-l} in @code{etags}.
-@item cut-mark
-@samp{-c} in @code{shar}.
+@item less-mode
+@samp{-l} in @code{wdiff}.
-@item cxref
-@samp{-x} in @code{ctags}.
+@item level-for-gzip
+@samp{-g} in @code{shar}.
-@item date
-@samp{-d} in @code{touch}.
+@item line-bytes
+@samp{-C} in @code{split}.
-@item debug
-@samp{-d} in Make and @code{m4};
-@samp{-t} in Bison.
+@item lines
+Used in @code{split}, @code{head}, and @code{tail}.
-@item define
-@samp{-D} in @code{m4}.
+@item link
+@samp{-l} in @code{cpio}.
-@item defines
-@samp{-d} in Bison and @code{ctags}.
+@item lint
+@itemx lint-old
+Used in @code{gawk}.
-@item delete
-@samp{-D} in @code{tar}.
+@item list
+@samp{-t} in @code{cpio};
+@samp{-l} in @code{recode}.
-@item dereference
-@samp{-L} in @code{chgrp}, @code{chown}, @code{cpio}, @code{du},
-@code{ls}, and @code{tar}.
+@item list
+@samp{-t} in @code{tar}.
-@item dereference-args
-@samp{-D} in @code{du}.
+@item literal
+@samp{-N} in @code{ls}.
-@item diacritics
-@samp{-d} in @code{recode}.
+@item load-average
+@samp{-l} in Make.
-@item dictionary-order
-@samp{-d} in @code{look}.
+@item login
+Used in @code{su}.
-@item diff
-@samp{-d} in @code{tar}.
+@item machine
+No listing of which programs already use this;
+someone should check to
+see if any actually do and tell @code{gnu@@prep.ai.mit.edu}.
-@item digits
-@samp{-n} in @code{csplit}.
+@item macro-name
+@samp{-M} in @code{ptx}.
-@item directory
-Specify the directory to use, in various programs. In @code{ls}, it
-means to show directories themselves rather than their contents. In
-@code{rm} and @code{ln}, it means to not treat links to directories
-specially.
+@item mail
+@samp{-m} in @code{hello} and @code{uname}.
-@item discard-all
-@samp{-x} in @code{strip}.
+@item make-directories
+@samp{-d} in @code{cpio}.
-@item discard-locals
-@samp{-X} in @code{strip}.
+@item makefile
+@samp{-f} in Make.
-@item dry-run
-@samp{-n} in Make.
+@item mapped
+Used in GDB.
-@item ed
-@samp{-e} in @code{diff}.
+@item max-args
+@samp{-n} in @code{xargs}.
-@item elide-empty-files
-@samp{-z} in @code{csplit}.
+@item max-chars
+@samp{-n} in @code{xargs}.
+
+@item max-lines
+@samp{-l} in @code{xargs}.
-@item end-delete
-@samp{-x} in @code{wdiff}.
+@item max-load
+@samp{-l} in Make.
-@item end-insert
-@samp{-z} in @code{wdiff}.
+@item max-procs
+@samp{-P} in @code{xargs}.
-@item entire-new-file
-@samp{-N} in @code{diff}.
+@item mesg
+@samp{-T} in @code{who}.
-@item environment-overrides
-@samp{-e} in Make.
+@item message
+@samp{-T} in @code{who}.
-@item eof
-@samp{-e} in @code{xargs}.
+@item minimal
+@samp{-d} in @code{diff}.
-@item epoch
-Used in GDB.
+@item mixed-uuencode
+@samp{-M} in @code{shar}.
-@item error-limit
-Used in Makeinfo.
+@item mode
+@samp{-m} in @code{install}, @code{mkdir}, and @code{mkfifo}.
-@item error-output
-@samp{-o} in @code{m4}.
+@item modification-time
+@samp{-m} in @code{tar}.
-@item escape
-@samp{-b} in @code{ls}.
+@item multi-volume
+@samp{-M} in @code{tar}.
-@item exclude-from
-@samp{-X} in @code{tar}.
+@item name-prefix
+@samp{-a} in Bison.
-@item exec
-Used in GDB.
+@item nesting-limit
+@samp{-L} in @code{m4}.
-@item exit
-@samp{-x} in @code{xargs}.
+@item net-headers
+@samp{-a} in @code{shar}.
-@item exit-0
-@samp{-e} in @code{unshar}.
+@item new-file
+@samp{-W} in Make.
-@item expand-tabs
-@samp{-t} in @code{diff}.
+@item no-builtin-rules
+@samp{-r} in Make.
-@item expression
-@samp{-e} in @code{sed}.
+@item no-character-count
+@samp{-w} in @code{shar}.
-@item extern-only
-@samp{-g} in @code{nm}.
+@item no-check-existing
+@samp{-x} in @code{shar}.
-@item extract
-@samp{-i} in @code{cpio};
-@samp{-x} in @code{tar}.
+@item no-common
+@samp{-3} in @code{wdiff}.
-@item faces
-@samp{-f} in @code{finger}.
+@item no-create
+@samp{-c} in @code{touch}.
-@item fast
-@samp{-f} in @code{su}.
+@item no-defines
+@samp{-D} in @code{etags}.
-@item fatal-warnings
-@samp{-E} in @code{m4}.
+@item no-deleted
+@samp{-1} in @code{wdiff}.
-@item field-separator
-p@samp{-F} in Gawk.
+@item no-dereference
+@samp{-d} in @code{cp}.
-@item file
-@samp{-f} in Gawk, @code{info}, Make, @code{mt}, and @code{tar};
-@samp{-n} in @code{sed};
-@samp{-r} in @code{touch}.
+@item no-inserted
+@samp{-2} in @code{wdiff}.
-@item file-prefix
-@samp{-b} in Bison.
+@item no-keep-going
+@samp{-S} in Make.
-@item file-type
-@samp{-F} in @code{ls}.
+@item no-lines
+@samp{-l} in Bison.
-@item files-from
-@samp{-T} in @code{tar}.
+@item no-piping
+@samp{-P} in @code{shar}.
-@item fill-column
-Used in Makeinfo.
+@item no-prof
+@samp{-e} in @code{gprof}.
-@item flag-truncation
-@samp{-F} in @code{ptx}.
+@item no-regex
+@samp{-R} in @code{etags}.
-@item fixed-output-files
-@samp{-y} in Bison.
+@item no-sort
+@samp{-p} in @code{nm}.
-@item follow
-@samp{-f} in @code{tail}.
+@item no-split
+Used in @code{makeinfo}.
-@item footnote-style
-Used in Makeinfo.
+@item no-static
+@samp{-a} in @code{gprof}.
-@item force
-@samp{-f} in @code{cp}, @code{ln}, @code{mv}, and @code{rm}.
+@item no-time
+@samp{-E} in @code{gprof}.
-@item force-prefix
-@samp{-F} in @code{shar}.
+@item no-timestamp
+@samp{-m} in @code{shar}.
-@item format
-Used in @code{ls}, @code{time}, and @code{ptx}.
+@item no-validate
+Used in @code{makeinfo}.
-@item freeze-state
-@samp{-F} in @code{m4}.
+@item no-warn
+Used in various programs to inhibit warnings.
-@item fullname
-Used in GDB.
+@item node
+@samp{-n} in @code{info}.
-@item gap-size
-@samp{-g} in @code{ptx}.
+@item nodename
+@samp{-n} in @code{uname}.
-@item get
-@samp{-x} in @code{tar}.
+@item nonmatching
+@samp{-f} in @code{cpio}.
-@item graphic
-@samp{-i} in @code{ul}.
+@item nstuff
+@samp{-n} in @code{objdump}.
-@item graphics
-@samp{-g} in @code{recode}.
+@item null
+@samp{-0} in @code{xargs}.
-@item group
-@samp{-g} in @code{install}.
+@item number
+@samp{-n} in @code{cat}.
-@item gzip
-@samp{-z} in @code{tar} and @code{shar}.
+@item number-nonblank
+@samp{-b} in @code{cat}.
-@item hashsize
-@samp{-H} in @code{m4}.
+@item numeric-sort
+@samp{-n} in @code{nm}.
-@item header
-@samp{-h} in @code{objdump} and @code{recode}
+@item numeric-uid-gid
+@samp{-n} in @code{cpio} and @code{ls}.
-@item heading
-@samp{-H} in @code{who}.
+@item nx
+Used in GDB.
-@item help
-Used to ask for brief usage information.
+@item old-archive
+@samp{-o} in @code{tar}.
-@item here-delimiter
-@samp{-d} in @code{shar}.
+@item old-file
+@samp{-o} in Make.
-@item hide-control-chars
-@samp{-q} in @code{ls}.
+@item one-file-system
+@samp{-l} in @code{tar}, @code{cp}, and @code{du}.
-@item idle
-@samp{-u} in @code{who}.
+@item only-file
+@samp{-o} in @code{ptx}.
-@item ifdef
-@samp{-D} in @code{diff}.
+@item only-prof
+@samp{-f} in @code{gprof}.
-@item ignore
-@samp{-I} in @code{ls};
-@samp{-x} in @code{recode}.
+@item only-time
+@samp{-F} in @code{gprof}.
-@item ignore-all-space
-@samp{-w} in @code{diff}.
+@item output
+In various programs, specify the output file name.
-@item ignore-backups
-@samp{-B} in @code{ls}.
+@item output-prefix
+@samp{-o} in @code{shar}.
-@item ignore-blank-lines
-@samp{-B} in @code{diff}.
+@item override
+@samp{-o} in @code{rm}.
-@item ignore-case
-@samp{-f} in @code{look} and @code{ptx};
-@samp{-i} in @code{diff} and @code{wdiff}.
+@item overwrite
+@samp{-c} in @code{unshar}.
-@item ignore-errors
-@samp{-i} in Make.
+@item owner
+@samp{-o} in @code{install}.
-@item ignore-file
-@samp{-i} in @code{ptx}.
+@item paginate
+@samp{-l} in @code{diff}.
-@item ignore-indentation
-@samp{-I} in @code{etags}.
+@item paragraph-indent
+Used in @code{makeinfo}.
-@item ignore-init-file
-@samp{-f} in Oleo.
+@item parents
+@samp{-p} in @code{mkdir} and @code{rmdir}.
-@item ignore-interrupts
-@samp{-i} in @code{tee}.
+@item pass-all
+@samp{-p} in @code{ul}.
-@item ignore-matching-lines
-@samp{-I} in @code{diff}.
+@item pass-through
+@samp{-p} in @code{cpio}.
-@item ignore-space-change
-@samp{-b} in @code{diff}.
+@item port
+@samp{-P} in @code{finger}.
-@item ignore-zeros
-@samp{-i} in @code{tar}.
+@item portability
+@samp{-c} in @code{cpio} and @code{tar}.
-@item include
-@samp{-i} in @code{etags};
-@samp{-I} in @code{m4}.
+@item posix
+Used in @code{gawk}.
-@item include-dir
-@samp{-I} in Make.
+@item prefix-builtins
+@samp{-P} in @code{m4}.
+
+@item prefix
+@samp{-f} in @code{csplit}.
-@item incremental
-@samp{-G} in @code{tar}.
+@item preserve
+Used in @code{tar} and @code{cp}.
-@item info
-@samp{-i}, @samp{-l}, and @samp{-m} in Finger.
+@item preserve-environment
+@samp{-p} in @code{su}.
-@item initial
-@samp{-i} in @code{expand}.
+@item preserve-modification-time
+@samp{-m} in @code{cpio}.
-@item initial-tab
-@samp{-T} in @code{diff}.
+@item preserve-order
+@samp{-s} in @code{tar}.
-@item inode
-@samp{-i} in @code{ls}.
+@item preserve-permissions
+@samp{-p} in @code{tar}.
-@item interactive
-@samp{-i} in @code{cp}, @code{ln}, @code{mv}, @code{rm};
-@samp{-e} in @code{m4};
-@samp{-p} in @code{xargs};
-@samp{-w} in @code{tar}.
+@item print
+@samp{-l} in @code{diff}.
-@item intermix-type
-@samp{-p} in @code{shar}.
+@item print-chars
+@samp{-L} in @code{cmp}.
-@item jobs
-@samp{-j} in Make.
+@item print-data-base
+@samp{-p} in Make.
-@item just-print
-@samp{-n} in Make.
+@item print-directory
+@samp{-w} in Make.
-@item keep-going
-@samp{-k} in Make.
+@item print-file-name
+@samp{-o} in @code{nm}.
-@item keep-files
-@samp{-k} in @code{csplit}.
+@item print-symdefs
+@samp{-s} in @code{nm}.
-@item kilobytes
-@samp{-k} in @code{du} and @code{ls}.
+@item printer
+@samp{-p} in @code{wdiff}.
-@item language
-@samp{-l} in @code{etags}.
+@item prompt
+@samp{-p} in @code{ed}.
-@item less-mode
-@samp{-l} in @code{wdiff}.
+@item query-user
+@samp{-X} in @code{shar}.
-@item level-for-gzip
-@samp{-g} in @code{shar}.
+@item question
+@samp{-q} in Make.
-@item line-bytes
-@samp{-C} in @code{split}.
+@item quiet
+Used in many programs to inhibit the usual output. @strong{Note:} every
+program accepting @samp{--quiet} should accept @samp{--silent} as a
+synonym.
-@item lines
-Used in @code{split}, @code{head}, and @code{tail}.
+@item quiet-unshar
+@samp{-Q} in @code{shar}
-@item link
-@samp{-l} in @code{cpio}.
+@item quote-name
+@samp{-Q} in @code{ls}.
-@item lint
-Used in gawk (no corresponding single-letter option).
+@item rcs
+@samp{-n} in @code{diff}.
-@item list
-@samp{-t} in @code{cpio};
-@samp{-l} in @code{recode}.
+@item re-interval
+Used in @code{gawk}.
-@item list
-@samp{-t} in @code{tar}.
+@item read-full-blocks
+@samp{-B} in @code{tar}.
-@item literal
-@samp{-N} in @code{ls}.
+@item readnow
+Used in GDB.
-@item load-average
-@samp{-l} in Make.
+@item recon
+@samp{-n} in Make.
-@item login
-Used in @code{su}.
+@item record-number
+@samp{-R} in @code{tar}.
-@item machine
-No listing of which programs already use this;
-someone should check to
-see if any actually do and tell @code{gnu@@prep.ai.mit.edu}.
+@item recursive
+Used in @code{chgrp}, @code{chown}, @code{cp}, @code{ls}, @code{diff},
+and @code{rm}.
-@item macro-name
-@samp{-M} in @code{ptx}.
+@item reference-limit
+Used in @code{makeinfo}.
-@item mail
-@samp{-m} in @code{hello} and @code{uname}.
+@item references
+@samp{-r} in @code{ptx}.
-@item make-directories
-@samp{-d} in @code{cpio}.
+@item regex
+@samp{-r} in @code{tac} and @code{etags}.
-@item makefile
-@samp{-f} in Make.
+@item release
+@samp{-r} in @code{uname}.
-@item mapped
-Used in GDB.
+@item reload-state
+@samp{-R} in @code{m4}.
-@item max-args
-@samp{-n} in @code{xargs}.
+@item relocation
+@samp{-r} in @code{objdump}.
-@item max-chars
-@samp{-n} in @code{xargs}.
+@item rename
+@samp{-r} in @code{cpio}.
-@item max-lines
-@samp{-l} in @code{xargs}.
+@item replace
+@samp{-i} in @code{xargs}.
-@item max-load
-@samp{-l} in Make.
+@item report-identical-files
+@samp{-s} in @code{diff}.
-@item max-procs
-@samp{-P} in @code{xargs}.
+@item reset-access-time
+@samp{-a} in @code{cpio}.
-@item mesg
-@samp{-T} in @code{who}.
+@item reverse
+@samp{-r} in @code{ls} and @code{nm}.
-@item message
-@samp{-T} in @code{who}.
+@item reversed-ed
+@samp{-f} in @code{diff}.
-@item minimal
-@samp{-d} in @code{diff}.
+@item right-side-defs
+@samp{-R} in @code{ptx}.
-@item mixed-uuencode
-@samp{-M} in @code{shar}.
+@item same-order
+@samp{-s} in @code{tar}.
-@item mode
-@samp{-m} in @code{install}, @code{mkdir}, and @code{mkfifo}.
+@item same-permissions
+@samp{-p} in @code{tar}.
-@item modification-time
-@samp{-m} in @code{tar}.
+@item save
+@samp{-g} in @code{stty}.
-@item multi-volume
-@samp{-M} in @code{tar}.
+@item se
+Used in GDB.
-@item name-prefix
-@samp{-a} in Bison.
+@item sentence-regexp
+@samp{-S} in @code{ptx}.
-@item nesting-limit
-@samp{-L} in @code{m4}.
+@item separate-dirs
+@samp{-S} in @code{du}.
-@item net-headers
-@samp{-a} in @code{shar}.
+@item separator
+@samp{-s} in @code{tac}.
-@item new-file
-@samp{-W} in Make.
+@item sequence
+Used by @code{recode} to chose files or pipes for sequencing passes.
-@item no-builtin-rules
-@samp{-r} in Make.
+@item shell
+@samp{-s} in @code{su}.
-@item no-character-count
-@samp{-w} in @code{shar}.
+@item show-all
+@samp{-A} in @code{cat}.
-@item no-check-existing
-@samp{-x} in @code{shar}.
+@item show-c-function
+@samp{-p} in @code{diff}.
-@item no-common
-@samp{-3} in @code{wdiff}.
+@item show-ends
+@samp{-E} in @code{cat}.
-@item no-create
-@samp{-c} in @code{touch}.
+@item show-function-line
+@samp{-F} in @code{diff}.
-@item no-defines
-@samp{-D} in @code{etags}.
+@item show-tabs
+@samp{-T} in @code{cat}.
-@item no-deleted
-@samp{-1} in @code{wdiff}.
+@item silent
+Used in many programs to inhibit the usual output.
+@strong{Note:} every program accepting
+@samp{--silent} should accept @samp{--quiet} as a synonym.
-@item no-dereference
-@samp{-d} in @code{cp}.
+@item size
+@samp{-s} in @code{ls}.
-@item no-inserted
-@samp{-2} in @code{wdiff}.
+@item sort
+Used in @code{ls}.
-@item no-keep-going
-@samp{-S} in Make.
+@item source
+@samp{-W source} in @code{gawk}.
-@item no-lines
-@samp{-l} in Bison.
+@item sparse
+@samp{-S} in @code{tar}.
-@item no-piping
-@samp{-P} in @code{shar}.
+@item speed-large-files
+@samp{-H} in @code{diff}.
-@item no-prof
-@samp{-e} in @code{gprof}.
+@item split-at
+@samp{-E} in @code{unshar}.
-@item no-regex
-@samp{-R} in @code{etags}.
+@item split-size-limit
+@samp{-L} in @code{shar}.
-@item no-sort
-@samp{-p} in @code{nm}.
+@item squeeze-blank
+@samp{-s} in @code{cat}.
-@item no-split
-Used in Makeinfo.
+@item start-delete
+@samp{-w} in @code{wdiff}.
+
+@item start-insert
+@samp{-y} in @code{wdiff}.
-@item no-static
-@samp{-a} in @code{gprof}.
+@item starting-file
+Used in @code{tar} and @code{diff} to specify which file within
+a directory to start processing with.
-@item no-time
-@samp{-E} in @code{gprof}.
+@item statistics
+@samp{-s} in @code{wdiff}.
-@item no-timestamp
-@samp{-m} in @code{shar}.
+@item stdin-file-list
+@samp{-S} in @code{shar}.
-@item no-validate
-Used in Makeinfo.
+@item stop
+@samp{-S} in Make.
-@item no-warn
-Used in various programs to inhibit warnings.
+@item strict
+@samp{-s} in @code{recode}.
-@item node
-@samp{-n} in @code{info}.
+@item strip
+@samp{-s} in @code{install}.
-@item nodename
-@samp{-n} in @code{uname}.
+@item strip-all
+@samp{-s} in @code{strip}.
-@item nonmatching
-@samp{-f} in @code{cpio}.
+@item strip-debug
+@samp{-S} in @code{strip}.
-@item nstuff
-@samp{-n} in @code{objdump}.
+@item submitter
+@samp{-s} in @code{shar}.
-@item null
-@samp{-0} in @code{xargs}.
+@item suffix
+@samp{-S} in @code{cp}, @code{ln}, @code{mv}.
-@item number
-@samp{-n} in @code{cat}.
+@item suffix-format
+@samp{-b} in @code{csplit}.
-@item number-nonblank
-@samp{-b} in @code{cat}.
+@item sum
+@samp{-s} in @code{gprof}.
-@item numeric-sort
-@samp{-n} in @code{nm}.
+@item summarize
+@samp{-s} in @code{du}.
-@item numeric-uid-gid
-@samp{-n} in @code{cpio} and @code{ls}.
+@item symbolic
+@samp{-s} in @code{ln}.
-@item nx
-Used in GDB.
+@item symbols
+Used in GDB and @code{objdump}.
-@item old-archive
-@samp{-o} in @code{tar}.
+@item synclines
+@samp{-s} in @code{m4}.
-@item old-file
-@samp{-o} in Make.
+@item sysname
+@samp{-s} in @code{uname}.
-@item one-file-system
-@samp{-l} in @code{tar}, @code{cp}, and @code{du}.
+@item tabs
+@samp{-t} in @code{expand} and @code{unexpand}.
-@item only-file
-@samp{-o} in @code{ptx}.
+@item tabsize
+@samp{-T} in @code{ls}.
-@item only-prof
-@samp{-f} in @code{gprof}.
+@item terminal
+@samp{-T} in @code{tput} and @code{ul}.
+@samp{-t} in @code{wdiff}.
-@item only-time
-@samp{-F} in @code{gprof}.
+@item text
+@samp{-a} in @code{diff}.
-@item output
-In various programs, specify the output file name.
+@item text-files
+@samp{-T} in @code{shar}.
-@item output-prefix
-@samp{-o} in @code{shar}.
+@item time
+Used in @code{ls} and @code{touch}.
-@item override
-@samp{-o} in @code{rm}.
+@item to-stdout
+@samp{-O} in @code{tar}.
-@item overwrite
-@samp{-c} in @code{unshar}.
+@item total
+@samp{-c} in @code{du}.
-@item owner
-@samp{-o} in @code{install}.
+@item touch
+@samp{-t} in Make, @code{ranlib}, and @code{recode}.
-@item paginate
-@samp{-l} in @code{diff}.
+@item trace
+@samp{-t} in @code{m4}.
-@item paragraph-indent
-Used in Makeinfo.
+@item traditional
+@samp{-t} in @code{hello};
+@samp{-W traditional} in @code{gawk};
+@samp{-G} in @code{ed}, @code{m4}, and @code{ptx}.
-@item parents
-@samp{-p} in @code{mkdir} and @code{rmdir}.
+@item tty
+Used in GDB.
-@item pass-all
-@samp{-p} in @code{ul}.
+@item typedefs
+@samp{-t} in @code{ctags}.
-@item pass-through
-@samp{-p} in @code{cpio}.
+@item typedefs-and-c++
+@samp{-T} in @code{ctags}.
-@item port
-@samp{-P} in @code{finger}.
+@item typeset-mode
+@samp{-t} in @code{ptx}.
-@item portability
-@samp{-c} in @code{cpio} and @code{tar}.
+@item uncompress
+@samp{-z} in @code{tar}.
-@item posix
-Used in gawk (no corresponding single-letter option).
+@item unconditional
+@samp{-u} in @code{cpio}.
-@item prefix-builtins
-@samp{-P} in @code{m4}.
+@item undefine
+@samp{-U} in @code{m4}.
-@item prefix
-@samp{-f} in @code{csplit}.
+@item undefined-only
+@samp{-u} in @code{nm}.
-@item preserve
-Used in @code{tar} and @code{cp}.
+@item update
+@samp{-u} in @code{cp}, @code{ctags}, @code{mv}, @code{tar}.
-@item preserve-environment
-@samp{-p} in @code{su}.
+@item usage
+Used in @code{gawk}; same as @samp{--help}.
-@item preserve-modification-time
-@samp{-m} in @code{cpio}.
+@item uuencode
+@samp{-B} in @code{shar}.
-@item preserve-order
-@samp{-s} in @code{tar}.
+@item vanilla-operation
+@samp{-V} in @code{shar}.
-@item preserve-permissions
-@samp{-p} in @code{tar}.
+@item verbose
+Print more information about progress. Many programs support this.
-@item print
-@samp{-l} in @code{diff}.
+@item verify
+@samp{-W} in @code{tar}.
-@item print-chars
-@samp{-L} in @code{cmp}.
+@item version
+Print the version number.
-@item print-data-base
-@samp{-p} in Make.
+@item version-control
+@samp{-V} in @code{cp}, @code{ln}, @code{mv}.
-@item print-directory
-@samp{-w} in Make.
+@item vgrind
+@samp{-v} in @code{ctags}.
-@item print-file-name
-@samp{-o} in @code{nm}.
+@item volume
+@samp{-V} in @code{tar}.
-@item print-symdefs
-@samp{-s} in @code{nm}.
+@item what-if
+@samp{-W} in Make.
-@item printer
-@samp{-p} in @code{wdiff}.
+@item whole-size-limit
+@samp{-l} in @code{shar}.
-@item prompt
-@samp{-p} in @code{ed}.
+@item width
+@samp{-w} in @code{ls} and @code{ptx}.
-@item query-user
-@samp{-X} in @code{shar}.
+@item word-regexp
+@samp{-W} in @code{ptx}.
-@item question
-@samp{-q} in Make.
+@item writable
+@samp{-T} in @code{who}.
-@item quiet
-Used in many programs to inhibit the usual output. @strong{Note:} every
-program accepting @samp{--quiet} should accept @samp{--silent} as a
-synonym.
+@item zeros
+@samp{-z} in @code{gprof}.
-@item quiet-unshar
-@samp{-Q} in @code{shar}
+@end table
-@item quote-name
-@samp{-Q} in @code{ls}.
+@node Writing C
+@chapter Making The Best Use of C
-@item rcs
-@samp{-n} in @code{diff}.
+This @value{CHAPTER} provides advice on how best to use the C language
+when writing GNU software.
-@item read-full-blocks
-@samp{-B} in @code{tar}.
+@menu
+* Formatting:: Formatting Your Source Code
+* Comments:: Commenting Your Work
+* Syntactic Conventions:: Clean Use of C Constructs
+* Names:: Naming Variables and Functions
+* System Functions:: Portability and ``standard'' library functions
+@end menu
-@item readnow
-Used in GDB.
+@node Formatting
+@section Formatting Your Source Code
-@item recon
-@samp{-n} in Make.
+It is important to put the open-brace that starts the body of a C
+function in column zero, and avoid putting any other open-brace or
+open-parenthesis or open-bracket in column zero. Several tools look
+for open-braces in column zero to find the beginnings of C functions.
+These tools will not work on code not formatted that way.
-@item record-number
-@samp{-R} in @code{tar}.
+It is also important for function definitions to start the name of the
+function in column zero. This helps people to search for function
+definitions, and may also help certain tools recognize them. Thus,
+the proper format is this:
-@item recursive
-Used in @code{chgrp}, @code{chown}, @code{cp}, @code{ls}, @code{diff},
-and @code{rm}.
+@example
+static char *
+concat (s1, s2) /* Name starts in column zero here */
+ char *s1, *s2;
+@{ /* Open brace in column zero here */
+ @dots{}
+@}
+@end example
-@item reference-limit
-Used in Makeinfo.
+@noindent
+or, if you want to use @sc{ANSI} C, format the definition like this:
-@item references
-@samp{-r} in @code{ptx}.
+@example
+static char *
+concat (char *s1, char *s2)
+@{
+ @dots{}
+@}
+@end example
-@item regex
-@samp{-r} in @code{tac} and @code{etags}.
+In @sc{ANSI} C, if the arguments don't fit nicely on one line,
+split it like this:
-@item release
-@samp{-r} in @code{uname}.
+@example
+int
+lots_of_args (int an_integer, long a_long, short a_short,
+ double a_double, float a_float)
+@dots{}
+@end example
-@item reload-state
-@samp{-R} in @code{m4}.
+For the body of the function, we prefer code formatted like this:
-@item relocation
-@samp{-r} in @code{objdump}.
+@example
+if (x < foo (y, z))
+ haha = bar[4] + 5;
+else
+ @{
+ while (z)
+ @{
+ haha += foo (z, z);
+ z--;
+ @}
+ return ++x + bar ();
+ @}
+@end example
-@item rename
-@samp{-r} in @code{cpio}.
+We find it easier to read a program when it has spaces before the
+open-parentheses and after the commas. Especially after the commas.
-@item replace
-@samp{-i} in @code{xargs}.
+When you split an expression into multiple lines, split it
+before an operator, not after one. Here is the right way:
-@item report-identical-files
-@samp{-s} in @code{diff}.
+@example
+if (foo_this_is_long && bar > win (x, y, z)
+ && remaining_condition)
+@end example
-@item reset-access-time
-@samp{-a} in @code{cpio}.
+Try to avoid having two operators of different precedence at the same
+level of indentation. For example, don't write this:
-@item reverse
-@samp{-r} in @code{ls} and @code{nm}.
+@example
+mode = (inmode[j] == VOIDmode
+ || GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j])
+ ? outmode[j] : inmode[j]);
+@end example
-@item reversed-ed
-@samp{-f} in @code{diff}.
+Instead, use extra parentheses so that the indentation shows the nesting:
-@item right-side-defs
-@samp{-R} in @code{ptx}.
+@example
+mode = ((inmode[j] == VOIDmode
+ || (GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j])))
+ ? outmode[j] : inmode[j]);
+@end example
-@item same-order
-@samp{-s} in @code{tar}.
+Insert extra parentheses so that Emacs will indent the code properly.
+For example, the following indentation looks nice if you do it by hand,
+but Emacs would mess it up:
-@item same-permissions
-@samp{-p} in @code{tar}.
+@example
+v = rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
+ + rup->ru_stime.tv_sec*1000 + rup->ru_stime.tv_usec/1000;
+@end example
-@item save
-@samp{-g} in @code{stty}.
+But adding a set of parentheses solves the problem:
-@item se
-Used in GDB.
+@example
+v = (rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
+ + rup->ru_stime.tv_sec*1000 + rup->ru_stime.tv_usec/1000);
+@end example
-@item sentence-regexp
-@samp{-S} in @code{ptx}.
+Format do-while statements like this:
-@item separate-dirs
-@samp{-S} in @code{du}.
+@example
+do
+ @{
+ a = foo (a);
+ @}
+while (a > 0);
+@end example
-@item separator
-@samp{-s} in @code{tac}.
+Please use formfeed characters (control-L) to divide the program into
+pages at logical places (but not within a function). It does not matter
+just how long the pages are, since they do not have to fit on a printed
+page. The formfeeds should appear alone on lines by themselves.
-@item sequence
-Used by @code{recode} to chose files or pipes for sequencing passes.
-@item shell
-@samp{-s} in @code{su}.
+@node Comments
+@section Commenting Your Work
-@item show-all
-@samp{-A} in @code{cat}.
+Every program should start with a comment saying briefly what it is for.
+Example: @samp{fmt - filter for simple filling of text}.
-@item show-c-function
-@samp{-p} in @code{diff}.
+Please put a comment on each function saying what the function does,
+what sorts of arguments it gets, and what the possible values of
+arguments mean and are used for. It is not necessary to duplicate in
+words the meaning of the C argument declarations, if a C type is being
+used in its customary fashion. If there is anything nonstandard about
+its use (such as an argument of type @code{char *} which is really the
+address of the second character of a string, not the first), or any
+possible values that would not work the way one would expect (such as,
+that strings containing newlines are not guaranteed to work), be sure
+to say so.
-@item show-ends
-@samp{-E} in @code{cat}.
+Also explain the significance of the return value, if there is one.
-@item show-function-line
-@samp{-F} in @code{diff}.
+Please put two spaces after the end of a sentence in your comments, so
+that the Emacs sentence commands will work. Also, please write
+complete sentences and capitalize the first word. If a lower-case
+identifier comes at the beginning of a sentence, don't capitalize it!
+Changing the spelling makes it a different identifier. If you don't
+like starting a sentence with a lower case letter, write the sentence
+differently (e.g., ``The identifier lower-case is @dots{}'').
-@item show-tabs
-@samp{-T} in @code{cat}.
+The comment on a function is much clearer if you use the argument
+names to speak about the argument values. The variable name itself
+should be lower case, but write it in upper case when you are speaking
+about the value rather than the variable itself. Thus, ``the inode
+number NODE_NUM'' rather than ``an inode''.
-@item silent
-Used in many programs to inhibit the usual output.
-@strong{Note:} every program accepting
-@samp{--silent} should accept @samp{--quiet} as a synonym.
+There is usually no purpose in restating the name of the function in
+the comment before it, because the reader can see that for himself.
+There might be an exception when the comment is so long that the function
+itself would be off the bottom of the screen.
-@item size
-@samp{-s} in @code{ls}.
+There should be a comment on each static variable as well, like this:
-@item sort
-Used in @code{ls}.
+@example
+/* Nonzero means truncate lines in the display;
+ zero means continue them. */
+int truncate_lines;
+@end example
-@item source
-Used in gawk (no corresponding single-letter option).
+Every @samp{#endif} should have a comment, except in the case of short
+conditionals (just a few lines) that are not nested. The comment should
+state the condition of the conditional that is ending, @emph{including
+its sense}. @samp{#else} should have a comment describing the condition
+@emph{and sense} of the code that follows. For example:
-@item sparse
-@samp{-S} in @code{tar}.
+@example
+@group
+#ifdef foo
+ @dots{}
+#else /* not foo */
+ @dots{}
+#endif /* not foo */
+@end group
+@end example
-@item speed-large-files
-@samp{-H} in @code{diff}.
+@noindent
+but, by contrast, write the comments this way for a @samp{#ifndef}:
-@item split-at
-@samp{-E} in @code{unshar}.
+@example
+@group
+#ifndef foo
+ @dots{}
+#else /* foo */
+ @dots{}
+#endif /* foo */
+@end group
+@end example
-@item split-size-limit
-@samp{-L} in @code{shar}.
-@item squeeze-blank
-@samp{-s} in @code{cat}.
+@node Syntactic Conventions
+@section Clean Use of C Constructs
-@item start-delete
-@samp{-w} in @code{wdiff}.
+Please explicitly declare all arguments to functions.
+Don't omit them just because they are @code{int}s.
-@item start-insert
-@samp{-y} in @code{wdiff}.
+Declarations of external functions and functions to appear later in the
+source file should all go in one place near the beginning of the file
+(somewhere before the first function definition in the file), or else
+should go in a header file. Don't put @code{extern} declarations inside
+functions.
-@item starting-file
-Used in @code{tar} and @code{diff} to specify which file within
-a directory to start processing with.
+It used to be common practice to use the same local variables (with
+names like @code{tem}) over and over for different values within one
+function. Instead of doing this, it is better declare a separate local
+variable for each distinct purpose, and give it a name which is
+meaningful. This not only makes programs easier to understand, it also
+facilitates optimization by good compilers. You can also move the
+declaration of each local variable into the smallest scope that includes
+all its uses. This makes the program even cleaner.
-@item statistics
-@samp{-s} in @code{wdiff}.
+Don't use local variables or parameters that shadow global identifiers.
-@item stdin-file-list
-@samp{-S} in @code{shar}.
+Don't declare multiple variables in one declaration that spans lines.
+Start a new declaration on each line, instead. For example, instead
+of this:
-@item stop
-@samp{-S} in Make.
+@example
+@group
+int foo,
+ bar;
+@end group
+@end example
-@item strict
-@samp{-s} in @code{recode}.
+@noindent
+write either this:
-@item strip
-@samp{-s} in @code{install}.
+@example
+int foo, bar;
+@end example
-@item strip-all
-@samp{-s} in @code{strip}.
+@noindent
+or this:
-@item strip-debug
-@samp{-S} in @code{strip}.
+@example
+int foo;
+int bar;
+@end example
-@item submitter
-@samp{-s} in @code{shar}.
+@noindent
+(If they are global variables, each should have a comment preceding it
+anyway.)
-@item suffix
-@samp{-S} in @code{cp}, @code{ln}, @code{mv}.
+When you have an @code{if}-@code{else} statement nested in another
+@code{if} statement, always put braces around the @code{if}-@code{else}.
+Thus, never write like this:
-@item suffix-format
-@samp{-b} in @code{csplit}.
+@example
+if (foo)
+ if (bar)
+ win ();
+ else
+ lose ();
+@end example
-@item sum
-@samp{-s} in @code{gprof}.
+@noindent
+always like this:
-@item summarize
-@samp{-s} in @code{du}.
+@example
+if (foo)
+ @{
+ if (bar)
+ win ();
+ else
+ lose ();
+ @}
+@end example
-@item symbolic
-@samp{-s} in @code{ln}.
+If you have an @code{if} statement nested inside of an @code{else}
+statement, either write @code{else if} on one line, like this,
-@item symbols
-Used in GDB and @code{objdump}.
+@example
+if (foo)
+ @dots{}
+else if (bar)
+ @dots{}
+@end example
-@item synclines
-@samp{-s} in @code{m4}.
+@noindent
+with its @code{then}-part indented like the preceding @code{then}-part,
+or write the nested @code{if} within braces like this:
-@item sysname
-@samp{-s} in @code{uname}.
+@example
+if (foo)
+ @dots{}
+else
+ @{
+ if (bar)
+ @dots{}
+ @}
+@end example
-@item tabs
-@samp{-t} in @code{expand} and @code{unexpand}.
+Don't declare both a structure tag and variables or typedefs in the
+same declaration. Instead, declare the structure tag separately
+and then use it to declare the variables or typedefs.
-@item tabsize
-@samp{-T} in @code{ls}.
+Try to avoid assignments inside @code{if}-conditions. For example,
+don't write this:
-@item terminal
-@samp{-T} in @code{tput} and @code{ul}.
-@samp{-t} in @code{wdiff}.
+@example
+if ((foo = (char *) malloc (sizeof *foo)) == 0)
+ fatal ("virtual memory exhausted");
+@end example
-@item text
-@samp{-a} in @code{diff}.
+@noindent
+instead, write this:
-@item text-files
-@samp{-T} in @code{shar}.
+@example
+foo = (char *) malloc (sizeof *foo);
+if (foo == 0)
+ fatal ("virtual memory exhausted");
+@end example
-@item time
-Used in @code{ls} and @code{touch}.
+Don't make the program ugly to placate @code{lint}. Please don't insert any
+casts to @code{void}. Zero without a cast is perfectly fine as a null
+pointer constant.
-@item to-stdout
-@samp{-O} in @code{tar}.
+@node Names
+@section Naming Variables and Functions
-@item total
-@samp{-c} in @code{du}.
+Please use underscores to separate words in a name, so that the Emacs
+word commands can be useful within them. Stick to lower case; reserve
+upper case for macros and @code{enum} constants, and for name-prefixes
+that follow a uniform convention.
-@item touch
-@samp{-t} in Make, @code{ranlib}, and @code{recode}.
+For example, you should use names like @code{ignore_space_change_flag};
+don't use names like @code{iCantReadThis}.
-@item trace
-@samp{-t} in @code{m4}.
+Variables that indicate whether command-line options have been
+specified should be named after the meaning of the option, not after
+the option-letter. A comment should state both the exact meaning of
+the option and its letter. For example,
-@item traditional
-@samp{-t} in @code{hello};
-@samp{-G} in @code{ed}, @code{m4}, and @code{ptx}.
+@example
+@group
+/* Ignore changes in horizontal whitespace (-b). */
+int ignore_space_change_flag;
+@end group
+@end example
-@item tty
-Used in GDB.
+When you want to define names with constant integer values, use
+@code{enum} rather than @samp{#define}. GDB knows about enumeration
+constants.
-@item typedefs
-@samp{-t} in @code{ctags}.
+Use file names of 14 characters or less, to avoid creating gratuitous
+problems on older System V systems. You can use the program @code{doschk} to test for
+this. @code{doschk} also tests for potential name conflicts if the
+files were loaded onto an MS-DOS file system---something you may or may
+not care about.
-@item typedefs-and-c++
-@samp{-T} in @code{ctags}.
-@item typeset-mode
-@samp{-t} in @code{ptx}.
-@item uncompress
-@samp{-z} in @code{tar}.
+@node System Functions
+@section Calling System Functions
-@item unconditional
-@samp{-u} in @code{cpio}.
+C implementations differ substantially. ANSI C reduces but does not
+eliminate the incompatibilities; meanwhile, many users wish to compile
+GNU software with pre-ANSI compilers. This chapter gives
+recommendations for how to use the more or less standard C library
+functions to avoid unnecessary loss of portability.
-@item undefine
-@samp{-U} in @code{m4}.
+@itemize @bullet
+@item
+Don't use the value of @code{sprintf}. It returns the number of
+characters written on some systems, but not on all systems.
-@item undefined-only
-@samp{-u} in @code{nm}.
+@item
+Don't declare system functions explicitly.
-@item update
-@samp{-u} in @code{cp}, @code{ctags}, @code{mv}, @code{tar}.
+Almost any declaration for a system function is wrong on some system.
+To minimize conflicts, leave it to the system header files to declare
+system functions. If the headers don't declare a function, let it
+remain undeclared.
-@item usage
-Used in gawk (no corresponding single-letter option).
+While it may seem unclean to use a function without declaring it, in
+practice this works fine for most system library functions on the
+systems where this really happens. The problem is only theoretical. By
+contrast, actual declarations have frequently caused actual conflicts.
-@item uuencode
-@samp{-B} in @code{shar}.
+@item
+If you must declare a system function, don't specify the argument types.
+Use an old-style declaration, not an ANSI prototype. The more you
+specify about the function, the more likely a conflict.
-@item vanilla-operation
-@samp{-V} in @code{shar}.
+@item
+In particular, don't unconditionally declare @code{malloc} or
+@code{realloc}.
-@item verbose
-Print more information about progress. Many programs support this.
+Most GNU programs use those functions just once, in functions
+conventionally named @code{xmalloc} and @code{xrealloc}. These
+functions call @code{malloc} and @code{realloc}, respectively, and
+check the results.
-@item verify
-@samp{-W} in @code{tar}.
+Because @code{xmalloc} and @code{xrealloc} are defined in your program,
+you can declare them in other files without any risk of type conflict.
-@item version
-Print the version number.
+On most systems, @code{int} is the same length as a pointer; thus, the
+calls to @code{malloc} and @code{realloc} work fine. For the few
+exceptional systems (mostly 64-bit machines), you can use
+@strong{conditionalized} declarations of @code{malloc} and
+@code{realloc}---or put these declarations in configuration files
+specific to those systems.
-@item version-control
-@samp{-V} in @code{cp}, @code{ln}, @code{mv}.
+@item
+The string functions require special treatment. Some Unix systems have
+a header file @file{string.h}; others have @file{strings.h}. Neither
+file name is portable. There are two things you can do: use Autoconf to
+figure out which file to include, or don't include either file.
-@item vgrind
-@samp{-v} in @code{ctags}.
+@item
+If you don't include either strings file, you can't get declarations for
+the string functions from the header file in the usual way.
-@item volume
-@samp{-V} in @code{tar}.
+That causes less of a problem than you might think. The newer ANSI
+string functions are off-limits anyway because many systems still don't
+support them. The string functions you can use are these:
-@item what-if
-@samp{-W} in Make.
+@example
+strcpy strncpy strcat strncat
+strlen strcmp strncmp
+strchr strrchr
+@end example
-@item whole-size-limit
-@samp{-l} in @code{shar}.
+The copy and concatenate functions work fine without a declaration as
+long as you don't use their values. Using their values without a
+declaration fails on systems where the width of a pointer differs from
+the width of @code{int}, and perhaps in other cases. It is trivial to
+avoid using their values, so do that.
-@item width
-@samp{-w} in @code{ls} and @code{ptx}.
+The compare functions and @code{strlen} work fine without a declaration
+on most systems, possibly all the ones that GNU software runs on.
+You may find it necessary to declare them @strong{conditionally} on a
+few systems.
-@item word-regexp
-@samp{-W} in @code{ptx}.
+The search functions must be declared to return @code{char *}. Luckily,
+there is no variation in the data type they return. But there is
+variation in their names. Some systems give these functions the names
+@code{index} and @code{rindex}; other systems use the names
+@code{strchr} and @code{strrchr}. Some systems support both pairs of
+names, but neither pair works on all systems.
-@item writable
-@samp{-T} in @code{who}.
+You should pick a single pair of names and use it throughout your
+program. (Nowadays, it is better to choose @code{strchr} and
+@code{strrchr}.) Declare both of those names as functions returning
+@code{char *}. On systems which don't support those names, define them
+as macros in terms of the other pair. For example, here is what to put
+at the beginning of your file (or in a header) if you want to use the
+names @code{strchr} and @code{strrchr} throughout:
-@item zeros
-@samp{-z} in @code{gprof}.
+@example
+#ifndef HAVE_STRCHR
+#define strchr index
+#endif
+#ifndef HAVE_STRRCHR
+#define strrchr rindex
+#endif
-@end table
-@c longopts end here (keyword for isearch)
+char *strchr ();
+char *strrchr ();
+@end example
+@end itemize
+
+Here we assume that @code{HAVE_STRCHR} and @code{HAVE_STRRCHR} are
+macros defined in systems where the corresponding functions exist.
+One way to get them properly defined is to use Autoconf.
@node Documentation
@chapter Documenting Programs
* GNU Manuals:: Writing proper manuals.
* Manual Structure Details:: Specific structure conventions.
* NEWS File:: NEWS files supplement manuals.
+* Change Logs:: Recording Changes
* Man Pages:: Man pages are secondary.
* Reading other Manuals:: How far you can go in learning
- from other manuals.
+ from other manuals.
@end menu
@node GNU Manuals
The preferred way to document part of the GNU system is to write a
manual in the Texinfo formatting language. See the Texinfo manual,
-either the hardcopy or the version in the Emacs Info subsystem (@kbd{C-h
-i}).
+either the hardcopy, or the on-line version available through
+@code{info} or the Emacs Info subsystem (@kbd{C-h i}).
The manual should document all of the program's command-line options and
all of its commands. It should give examples of their use. But don't
should give a good introduction to a beginner reading through from the
start, and should also provide all the details that hackers want.
-That is not as hard as it sounds at first. Arrange each chapter as a
+That is not as hard as it first sounds. Arrange each chapter as a
logical breakdown of its topic, but order the sections, and write their
text, so that reading the chapter straight through makes sense. Do
likewise when structuring the book into chapters, and when structuring a
@section Manual Structure Details
The title page of the manual should state the version of the program
-which the manual applies to. The Top node of the manual should also
+to which the manual applies. The Top node of the manual should also
contain this information. If the manual is changing more frequently
than or independent of the program, also state a version number for
the manual in both of these places.
into a file named @file{ONEWS} and put a note at the end referring the
user to that file.
+@node Change Logs
+@section Change Logs
+
+Keep a change log for each directory, describing the changes made to
+source files in that directory. The purpose of this is so that people
+investigating bugs in the future will know about the changes that
+might have introduced the bug. Often a new bug can be found by
+looking at what was recently changed. More importantly, change logs
+can help eliminate conceptual inconsistencies between different parts
+of a program; they can give you a history of how the conflicting
+concepts arose.
+
+Use the Emacs command @kbd{M-x add-change-log-entry} to start a new
+entry in the
+change log. An entry should have an asterisk, the name of the changed
+file, and then in parentheses the name of the changed functions,
+variables or whatever, followed by a colon. Then describe the changes
+you made to that function or variable.
+
+Separate unrelated entries with blank lines. When two entries
+represent parts of the same change, so that they work together, then
+don't put blank lines between them. Then you can omit the file name
+and the asterisk when successive entries are in the same file.
+
+Here are some examples:
+
+@example
+* register.el (insert-register): Return nil.
+(jump-to-register): Likewise.
+
+* sort.el (sort-subr): Return nil.
+
+* tex-mode.el (tex-bibtex-file, tex-file, tex-region):
+Restart the tex shell if process is gone or stopped.
+(tex-shell-running): New function.
+
+* expr.c (store_one_arg): Round size up for move_block_to_reg.
+(expand_call): Round up when emitting USE insns.
+* stmt.c (assign_parms): Round size up for move_block_from_reg.
+@end example
+
+It's important to name the changed function or variable in full. Don't
+abbreviate function or variable names, and don't combine them.
+Subsequent maintainers will often
+search for a function name to find all the change log entries that
+pertain to it; if you abbreviate the name, they won't find it when they
+search. For example, some people are tempted to abbreviate groups of
+function names by writing @samp{* register.el
+(@{insert,jump-to@}-register)}; this is not a good idea, since searching
+for @code{jump-to-register} or @code{insert-register} would not find the
+entry.
+
+There's no need to describe the full purpose of the changes or how they
+work together. It is better to put such explanations in comments in the
+code. That's why just ``New function'' is enough; there is a comment
+with the function in the source to explain what it does.
+
+However, sometimes it is useful to write one line to describe the
+overall purpose of a large batch of changes.
+
+You can think of the change log as a conceptual ``undo list'' which
+explains how earlier versions were different from the current version.
+People can see the current version; they don't need the change log
+to tell them what is in it. What they want from a change log is a
+clear explanation of how the earlier version differed.
+
+When you change the calling sequence of a function in a simple
+fashion, and you change all the callers of the function, there is no
+need to make individual entries for all the callers. Just write in
+the entry for the function being called, ``All callers changed.''
+
+When you change just comments or doc strings, it is enough to write an
+entry for the file, without mentioning the functions. Write just,
+``Doc fix.'' There's no need to keep a change log for documentation
+files. This is because documentation is not susceptible to bugs that
+are hard to fix. Documentation does not consist of parts that must
+interact in a precisely engineered fashion; to correct an error, you
+need not know the history of the erroneous passage.
+
@node Man Pages
@section Man Pages
documentation. Copying from free documentation may be ok; please check
with the FSF about the individual case.
+@node Managing Releases
+@chapter The Release Process
+
+Making a release is more than just bundling up your source files in a
+tar file and putting it up for FTP. You should set up your software so
+that it can be configured to run on a variety of systems. Your Makefile
+should conform to the GNU standards described below, and your directory
+layout should also conform to the standards discussed below. Doing so
+makes it easy to include your package into the larger framework of
+all GNU software.
+
+@menu
+* Configuration:: How Configuration Should Work
+* Makefile Conventions:: Makefile Conventions
+* Releases:: Making Releases
+@end menu
+
+@node Configuration
+@section How Configuration Should Work
+
+Each GNU distribution should come with a shell script named
+@code{configure}. This script is given arguments which describe the
+kind of machine and system you want to compile the program for.
+
+The @code{configure} script must record the configuration options so
+that they affect compilation.
+
+One way to do this is to make a link from a standard name such as
+@file{config.h} to the proper configuration file for the chosen system.
+If you use this technique, the distribution should @emph{not} contain a
+file named @file{config.h}. This is so that people won't be able to
+build the program without configuring it first.
+
+Another thing that @code{configure} can do is to edit the Makefile. If
+you do this, the distribution should @emph{not} contain a file named
+@file{Makefile}. Instead, it should include a file @file{Makefile.in} which
+contains the input used for editing. Once again, this is so that people
+won't be able to build the program without configuring it first.
+
+If @code{configure} does write the @file{Makefile}, then @file{Makefile}
+should have a target named @file{Makefile} which causes @code{configure}
+to be rerun, setting up the same configuration that was set up last
+time. The files that @code{configure} reads should be listed as
+dependencies of @file{Makefile}.
+
+All the files which are output from the @code{configure} script should
+have comments at the beginning explaining that they were generated
+automatically using @code{configure}. This is so that users won't think
+of trying to edit them by hand.
+
+The @code{configure} script should write a file named @file{config.status}
+which describes which configuration options were specified when the
+program was last configured. This file should be a shell script which,
+if run, will recreate the same configuration.
+
+The @code{configure} script should accept an option of the form
+@samp{--srcdir=@var{dirname}} to specify the directory where sources are found
+(if it is not the current directory). This makes it possible to build
+the program in a separate directory, so that the actual source directory
+is not modified.
+
+If the user does not specify @samp{--srcdir}, then @code{configure} should
+check both @file{.} and @file{..} to see if it can find the sources. If
+it finds the sources in one of these places, it should use them from
+there. Otherwise, it should report that it cannot find the sources, and
+should exit with nonzero status.
+
+Usually the easy way to support @samp{--srcdir} is by editing a
+definition of @code{VPATH} into the Makefile. Some rules may need to
+refer explicitly to the specified source directory. To make this
+possible, @code{configure} can add to the Makefile a variable named
+@code{srcdir} whose value is precisely the specified directory.
+
+The @code{configure} script should also take an argument which specifies the
+type of system to build the program for. This argument should look like
+this:
+
+@example
+@var{cpu}-@var{company}-@var{system}
+@end example
+
+For example, a Sun 3 might be @samp{m68k-sun-sunos4.1}.
+
+The @code{configure} script needs to be able to decode all plausible
+alternatives for how to describe a machine. Thus, @samp{sun3-sunos4.1}
+would be a valid alias. For many programs, @samp{vax-dec-ultrix} would
+be an alias for @samp{vax-dec-bsd}, simply because the differences
+between Ultrix and @sc{BSD} are rarely noticeable, but a few programs
+might need to distinguish them.
+@c Real 4.4BSD now runs on some Suns.
+
+There is a shell script called @file{config.sub} that you can use
+as a subroutine to validate system types and canonicalize aliases.
+
+Other options are permitted to specify in more detail the software
+or hardware present on the machine, and include or exclude optional
+parts of the package:
+
+@table @samp
+@item --enable-@var{feature}@r{[}=@var{parameter}@r{]}
+Configure the package to build and install an optional user-level
+facility called @var{feature}. This allows users to choose which
+optional features to include. Giving an optional @var{parameter} of
+@samp{no} should omit @var{feature}, if it is built by default.
+
+No @samp{--enable} option should @strong{ever} cause one feature to
+replace another. No @samp{--enable} option should ever substitute one
+useful behavior for another useful behavior. The only proper use for
+@samp{--enable} is for questions of whether to build part of the program
+or exclude it.
+
+@item --with-@var{package}
+@c @r{[}=@var{parameter}@r{]}
+The package @var{package} will be installed, so configure this package
+to work with @var{package}.
+
+@c Giving an optional @var{parameter} of
+@c @samp{no} should omit @var{package}, if it is used by default.
+
+Possible values of @var{package} include @samp{x}, @samp{x-toolkit},
+@samp{gnu-as} (or @samp{gas}), @samp{gnu-ld}, @samp{gnu-libc}, and
+@samp{gdb}.
+
+Do not use a @samp{--with} option to specify the file name to use to
+find certain files. That is outside the scope of what @samp{--with}
+options are for.
+
+@item --nfp
+The target machine has no floating point processor.
+
+@item --gas
+The target machine assembler is GAS, the GNU assembler.
+This is obsolete; users should use @samp{--with-gnu-as} instead.
+
+@item --x
+The target machine has the X Window System installed.
+This is obsolete; users should use @samp{--with-x} instead.
+@end table
+
+All @code{configure} scripts should accept all of these ``detail''
+options, whether or not they make any difference to the particular
+package at hand. In particular, they should accept any option that
+starts with @samp{--with-} or @samp{--enable-}. This is so users will
+be able to configure an entire GNU source tree at once with a single set
+of options.
+
+You will note that the categories @samp{--with-} and @samp{--enable-}
+are narrow: they @strong{do not} provide a place for any sort of option
+you might think of. That is deliberate. We want to limit the possible
+configuration options in GNU software. We do not want GNU programs to
+have idiosyncratic configuration options.
+
+Packages that perform part of the compilation process may support cross-compilation.
+In such a case, the host and target machines for the program may be
+different. The @code{configure} script should normally treat the
+specified type of system as both the host and the target, thus producing
+a program which works for the same type of machine that it runs on.
+
+The way to build a cross-compiler, cross-assembler, or what have you, is
+to specify the option @samp{--host=@var{hosttype}} when running
+@code{configure}. This specifies the host system without changing the
+type of target system. The syntax for @var{hosttype} is the same as
+described above.
+
+Bootstrapping a cross-compiler requires compiling it on a machine other
+than the host it will run on. Compilation packages accept a
+configuration option @samp{--build=@var{hosttype}} for specifying the
+configuration on which you will compile them, in case that is different
+from the host.
+
+Programs for which cross-operation is not meaningful need not accept the
+@samp{--host} option, because configuring an entire operating system for
+cross-operation is not a meaningful thing.
+
+Some programs have ways of configuring themselves automatically. If
+your program is set up to do this, your @code{configure} script can simply
+ignore most of its arguments.
+
+@comment The makefile standards are in a separate file that is also
+@comment included by make.texinfo. Done by roland@gnu.ai.mit.edu on 1/6/93.
+@comment For this document, turn chapters into sections, etc.
+@lowersections
+@include make-stds.texi
+@raisesections
+
@node Releases
-@chapter Making Releases
+@section Making Releases
Package the distribution of Foo version 69.96 in a gzipped tar file
named @file{foo-69.96.tar.gz}. It should unpack into a subdirectory
to include non-source files in the distribution, provided they are
up-to-date and machine-independent, so that building the distribution
normally will never modify them. We commonly include non-source files
-produced by Bison, Lex, @TeX{}, and Makeinfo; this helps avoid
+produced by Bison, @code{lex}, @TeX{}, and @code{makeinfo}; this helps avoid
unnecessary dependencies between our distributions, so that users can
install whichever packages they want to install.
systems cannot handle this and that prevents unpacking the
distribution.
-Try to make sure that all the file names will be unique on MS-DOG. A
-name on MS-DOG consists of up to 8 characters, optionally followed by a
-period and up to three characters. MS-DOG will truncate extra
+Try to make sure that all the file names will be unique on MS-DOS. A
+name on MS-DOS consists of up to 8 characters, optionally followed by a
+period and up to three characters. MS-DOS will truncate extra
characters both before and after the period. Thus,
@file{foobarhacker.c} and @file{foobarhacker.o} are not ambiguous; they
are truncated to @file{foobarha.c} and @file{foobarha.o}, which are
distinct.
Include in your distribution a copy of the @file{texinfo.tex} you used
-to test print any @file{*.texinfo} files.
+to test print any @file{*.texinfo} or @file{*.texi} files.
Likewise, if your program uses small GNU software packages like regex,
getopt, obstack, or termcap, include them in the distribution file.
@setfilename standards.info
@settitle GNU Coding Standards
@c UPDATE THIS DATE WHENEVER YOU MAKE CHANGES!
-@set lastupdate 24 July 1995
+@set lastupdate 18 January 1996
@c %**end of header
@ifinfo
@end format
@end ifinfo
+@c @setchapternewpage odd
@setchapternewpage off
+@c This is used by a cross ref in make-stds.texi
+@set CODESTD 1
+@iftex
+@set CHAPTER chapter
+@end iftex
+@ifinfo
+@set CHAPTER node
+@end ifinfo
+
@ifinfo
GNU Coding Standards
-Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
+Copyright (C) 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@page
@vskip 0pt plus 1filll
-Copyright @copyright{} 1992, 1993, 1994 Free Software Foundation, Inc.
+Copyright @copyright{} 1992, 1993, 1994,1995 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@menu
* Preface:: About the GNU Coding Standards
-* Reading Non-Free Code:: Referring to Proprietary Programs
-* Contributions:: Accepting Contributions
-* Change Logs:: Recording Changes
-* Compatibility:: Compatibility with Other Implementations
-* Makefile Conventions:: Makefile Conventions
-* Configuration:: How Configuration Should Work
-* Source Language:: Using Languages Other Than C
-* Formatting:: Formatting Your Source Code
-* Comments:: Commenting Your Work
-* Syntactic Conventions:: Clean Use of C Constructs
-* Names:: Naming Variables, Functions and Files
-* Using Extensions:: Using Non-standard Features
-* System Functions:: Portability and ``standard'' library functions
-* Semantics:: Program Behavior for All Programs
-* Errors:: Formatting Error Messages
-* Libraries:: Library Behavior
-* Portability:: Portability As It Applies to GNU
-* User Interfaces:: Standards for Command Line Interfaces
+* Intellectual Property:: Keeping Free Software Free
+* Design Advice:: General Program Design
+* Program Behavior:: Program Behavior for All Programs
+* Writing C:: Making The Best Use of C
* Documentation:: Documenting Programs
-* Releases:: Making Releases
+* Managing Releases:: The Release Process
@end menu
@node Preface
The GNU Coding Standards were written by Richard Stallman and other GNU
Project volunteers. Their purpose is to make the GNU system clean,
consistent, and easy to install. This document can also be read as a
-guide to write portable, robust and reliable programs. It focuses on
+guide to writing portable, robust and reliable programs. It focuses on
programs written in C, but many of the rules and principles are useful
even if you write in another programming language. The rules often
state reasons for writing in a certain way.
This release of the GNU Coding Standards was last updated
@value{lastupdate}.
+@node Intellectual Property
+@chapter Keeping Free Software Free
+
+This @value{CHAPTER} discusses how you can make sure that GNU software
+remains unencumbered.
+
+@menu
+* Reading Non-Free Code:: Referring to Proprietary Programs
+* Contributions:: Accepting Contributions
+@end menu
+
@node Reading Non-Free Code
-@chapter Referring to Proprietary Programs
+@section Referring to Proprietary Programs
Don't in any circumstances refer to Unix source code for or during
your work on GNU! (Or to any other proprietary programs.)
@node Contributions
-@chapter Accepting Contributions
+@section Accepting Contributions
If someone else sends you a piece of code to add to the program you are
working on, we need legal papers to use it---the same sort of legal
contribution.
This applies both before you release the program and afterward. If
-you receive diffs to fix a bug, and they make significant change, we
+you receive diffs to fix a bug, and they make significant changes, we
need legal papers for it.
You don't need papers for changes of a few lines here or there, since
which you use. For example, if you write a different solution to the
problem, you don't need to get papers.
-I know this is frustrating; it's frustrating for us as well. But if
+We know this is frustrating; it's frustrating for us as well. But if
you don't wait, you are going out on a limb---for example, what if the
contributor's employer won't sign a disclaimer? You might have to take
that code out again!
contributor. We could be very embarrassed in court some day as a
result.
-@node Change Logs
-@chapter Change Logs
-
-Keep a change log for each directory, describing the changes made to
-source files in that directory. The purpose of this is so that people
-investigating bugs in the future will know about the changes that
-might have introduced the bug. Often a new bug can be found by
-looking at what was recently changed. More importantly, change logs
-can help eliminate conceptual inconsistencies between different parts
-of a program; they can give you a history of how the conflicting
-concepts arose.
-
-Use the Emacs command @kbd{M-x add-change-log-entry} to start a new
-entry in the
-change log. An entry should have an asterisk, the name of the changed
-file, and then in parentheses the name of the changed functions,
-variables or whatever, followed by a colon. Then describe the changes
-you made to that function or variable.
-
-Separate unrelated entries with blank lines. When two entries
-represent parts of the same change, so that they work together, then
-don't put blank lines between them. Then you can omit the file name
-and the asterisk when successive entries are in the same file.
-
-Here are some examples:
-
-@example
-* register.el (insert-register): Return nil.
-(jump-to-register): Likewise.
-
-* sort.el (sort-subr): Return nil.
-
-* tex-mode.el (tex-bibtex-file, tex-file, tex-region):
-Restart the tex shell if process is gone or stopped.
-(tex-shell-running): New function.
-
-* expr.c (store_one_arg): Round size up for move_block_to_reg.
-(expand_call): Round up when emitting USE insns.
-* stmt.c (assign_parms): Round size up for move_block_from_reg.
-@end example
-
-It's important to name the changed function or variable in full. Don't
-abbreviate them; don't combine them. Subsequent maintainers will often
-search for a function name to find all the change log entries that
-pertain to it; if you abbreviate the name, they won't find it when they
-search. For example, some people are tempted to abbreviate groups of
-function names by writing @samp{* register.el
-(@{insert,jump-to@}-register)}; this is not a good idea, since searching
-for @code{jump-to-register} or @code{insert-register} would not find the
-entry.
-
-There's no need to describe the full purpose of the changes or how they
-work together. It is better to put such explanations in comments in the
-code. That's why just ``New function'' is enough; there is a comment
-with the function in the source to explain what it does.
-
-However, sometimes it is useful to write one line to describe the
-overall purpose of a large batch of changes.
-
-You can think of the change log as a conceptual ``undo list'' which
-explains how earlier versions were different from the current version.
-People can see the current version; they don't need the change log
-to tell them what is in it. What they want from a change log is a
-clear explanation of how the earlier version differed.
-
-When you change the calling sequence of a function in a simple
-fashion, and you change all the callers of the function, there is no
-need to make individual entries for all the callers. Just write in
-the entry for the function being called, ``All callers changed.''
+@node Design Advice
+@chapter General Program Design
-When you change just comments or doc strings, it is enough to write an
-entry for the file, without mentioning the functions. Write just,
-``Doc fix.'' There's no need to keep a change log for documentation
-files. This is because documentation is not susceptible to bugs that
-are hard to fix. Documentation does not consist of parts that must
-interact in a precisely engineered fashion; to correct an error, you
-need not know the history of the erroneous passage.
+This @value{CHAPTER} discusses some of the issues you should take into
+account when designing your program.
+@menu
+* Compatibility:: Compatibility with Other Implementations
+* Using Extensions:: Using Non-standard Features
+* Source Language:: Using Languages Other Than C
+* Portability:: Portability As It Applies to GNU
+@end menu
@node Compatibility
-@chapter Compatibility with Other Implementations
+@section Compatibility with Other Implementations
+@c ADR: What are the exceptions?
With certain exceptions, utility programs and libraries for GNU should
be upward compatible with those in Berkeley Unix, and upward compatible
with @sc{ANSI} C if @sc{ANSI} C specifies their behavior, and upward
modes for each of them.
@sc{ANSI} C and @sc{POSIX} prohibit many kinds of extensions. Feel
-free to make the extensions anyway, and include a @samp{--ansi} or
+free to make the extensions anyway, and include a @samp{--ansi},
+@samp{--posix}, or
@samp{--compatible} option to turn them off. However, if the extension
has a significant chance of breaking any real programs or scripts,
then it is not really upward compatible. Try to redesign its
When a feature is used only by users (not by programs or command
files), and it is done poorly in Unix, feel free to replace it
completely with something totally different and better. (For example,
-vi is replaced with Emacs.) But it is nice to offer a compatible
-feature as well. (There is a free vi clone, so we offer it.)
+@code{vi} is replaced with Emacs.) But it is nice to offer a compatible
+feature as well. (There is a free @code{vi} clone, so we offer it.)
Additional useful features not in Berkeley Unix are welcome.
Additional programs with no counterpart in Unix may be useful,
but our first priority is usually to duplicate what Unix already
has.
-@comment The makefile standards are in a separate file that is also
-@comment included by make.texinfo. Done by roland@gnu.ai.mit.edu on 1/6/93.
-@include make-stds.texi
-
-@node Configuration
-@chapter How Configuration Should Work
+@node Using Extensions
+@section Using Non-standard Features
-Each GNU distribution should come with a shell script named
-@code{configure}. This script is given arguments which describe the
-kind of machine and system you want to compile the program for.
+Many GNU facilities that already exist support a number of convenient
+extensions over the comparable Unix facilities. Whether to use these
+extensions in implementing your program is a difficult question.
-The @code{configure} script must record the configuration options so
-that they affect compilation.
+On the one hand, using the extensions can make a cleaner program.
+On the other hand, people will not be able to build the program
+unless the other GNU tools are available. This might cause the
+program to work on fewer kinds of machines.
-One way to do this is to make a link from a standard name such as
-@file{config.h} to the proper configuration file for the chosen system.
-If you use this technique, the distribution should @emph{not} contain a
-file named @file{config.h}. This is so that people won't be able to
-build the program without configuring it first.
+With some extensions, it might be easy to provide both alternatives.
+For example, you can define functions with a ``keyword'' @code{INLINE}
+and define that as a macro to expand into either @code{inline} or
+nothing, depending on the compiler.
-Another thing that @code{configure} can do is to edit the Makefile. If
-you do this, the distribution should @emph{not} contain a file named
-@file{Makefile}. Instead, include a file @file{Makefile.in} which
-contains the input used for editing. Once again, this is so that people
-won't be able to build the program without configuring it first.
+In general, perhaps it is best not to use the extensions if you can
+straightforwardly do without them, but to use the extensions if they
+are a big improvement.
-If @code{configure} does write the @file{Makefile}, then @file{Makefile}
-should have a target named @file{Makefile} which causes @code{configure}
-to be rerun, setting up the same configuration that was set up last
-time. The files that @code{configure} reads should be listed as
-dependencies of @file{Makefile}.
+An exception to this rule are the large, established programs (such as
+Emacs) which run on a great variety of systems. Such programs would
+be broken by use of GNU extensions.
-All the files which are output from the @code{configure} script should
-have comments at the beginning explaining that they were generated
-automatically using @code{configure}. This is so that users won't think
-of trying to edit them by hand.
+Another exception is for programs that are used as part of
+compilation: anything that must be compiled with other compilers in
+order to bootstrap the GNU compilation facilities. If these require
+the GNU compiler, then no one can compile them without having them
+installed already. That would be no good.
-The @code{configure} script should write a file named @file{config.status}
-which describes which configuration options were specified when the
-program was last configured. This file should be a shell script which,
-if run, will recreate the same configuration.
+Since most computer systems do not yet implement @sc{ANSI} C, using the
+@sc{ANSI} C features is effectively using a GNU extension, so the
+same considerations apply. (Except for @sc{ANSI} features that we
+discourage, such as trigraphs---don't ever use them.)
-The @code{configure} script should accept an option of the form
-@samp{--srcdir=@var{dirname}} to specify the directory where sources are found
-(if it is not the current directory). This makes it possible to build
-the program in a separate directory, so that the actual source directory
-is not modified.
+@node Source Language
+@section Using Languages Other Than C
-If the user does not specify @samp{--srcdir}, then @code{configure} should
-check both @file{.} and @file{..} to see if it can find the sources. If
-it finds the sources in one of these places, it should use them from
-there. Otherwise, it should report that it cannot find the sources, and
-should exit with nonzero status.
+Using a language other than C is like using a non-standard feature: it
+will cause trouble for users. Even if GCC supports the other language,
+users may find it inconvenient to have to install the compiler for that
+other language in order to build your program. So please write in C.
-Usually the easy way to support @samp{--srcdir} is by editing a
-definition of @code{VPATH} into the Makefile. Some rules may need to
-refer explicitly to the specified source directory. To make this
-possible, @code{configure} can add to the Makefile a variable named
-@code{srcdir} whose value is precisely the specified directory.
+There are three exceptions for this rule:
-The @code{configure} script should also take an argument which specifies the
-type of system to build the program for. This argument should look like
-this:
+@itemize @bullet
+@item
+It is okay to use a special language if the same program contains an
+interpreter for that language.
-@example
-@var{cpu}-@var{company}-@var{system}
-@end example
+Thus, it is not a problem that GNU Emacs contains code written in Emacs
+Lisp, because it comes with a Lisp interpreter.
-For example, a Sun 3 might be @samp{m68k-sun-sunos4.1}.
+@item
+It is okay to use another language in a tool specifically intended for
+use with that language.
-The @code{configure} script needs to be able to decode all plausible
-alternatives for how to describe a machine. Thus, @samp{sun3-sunos4.1}
-would be a valid alias. For many programs, @samp{vax-dec-ultrix} would
-be an alias for @samp{vax-dec-bsd}, simply because the differences
-between Ultrix and @sc{BSD} are rarely noticeable, but a few programs
-might need to distinguish them.
-@c Real 4.4BSD now runs on some Suns.
+This is okay because the only people who want to build the tool will be
+those who have installed the other language anyway.
-There is a shell script called @file{config.sub} that you can use
-as a subroutine to validate system types and canonicalize aliases.
+@item
+If an application is not of extremely widespread interest, then perhaps
+it's not important if the application is inconvenient to install.
+@end itemize
-Other options are permitted to specify in more detail the software
-or hardware present on the machine, and include or exclude optional
-parts of the package:
+@node Portability
+@section Portability As It Applies to GNU
-@table @samp
-@item --enable-@var{feature}@r{[}=@var{parameter}@r{]}
-Configure the package to build and install an optional user-level
-facility called @var{feature}. This allows users to choose which
-optional features to include. Giving an optional @var{parameter} of
-@samp{no} should omit @var{feature}, if it is built by default.
+Much of what is called ``portability'' in the Unix world refers to
+porting to different Unix versions. This is a secondary consideration
+for GNU software, because its primary purpose is to run on top of one
+and only one kernel, the GNU kernel, compiled with one and only one C
+compiler, the GNU C compiler. The amount and kinds of variation among
+GNU systems on different cpu's will be like the variation among Berkeley
+4.3 systems on different cpu's.
-No @samp{--enable} option should @strong{ever} cause one feature to
-replace another. No @samp{--enable} option should ever substitute one
-useful behavior for another useful behavior. The only proper use for
-@samp{--enable} is for questions of whether to build part of the program
-or exclude it.
+All users today run GNU software on non-GNU systems. So supporting a
+variety of non-GNU systems is desirable; simply not paramount.
+The easiest way to achieve portability to a reasonable range of systems
+is to use Autoconf. It's unlikely that your program needs to know more
+information about the host machine than Autoconf can provide, simply
+because most of the programs that need such knowledge have already been
+written.
-@item --with-@var{package}
-@c @r{[}=@var{parameter}@r{]}
-The package @var{package} will be installed, so configure this package
-to work with @var{package}.
+It is difficult to be sure exactly what facilities the GNU kernel
+will provide, since it isn't finished yet. Therefore, assume you can
+use anything in 4.3; just avoid using the format of semi-internal data
+bases (e.g., directories) when there is a higher-level alternative
+(@code{readdir}).
-@c Giving an optional @var{parameter} of
-@c @samp{no} should omit @var{package}, if it is used by default.
-
-Possible values of @var{package} include @samp{x}, @samp{x-toolkit},
-@samp{gnu-as} (or @samp{gas}), @samp{gnu-ld}, @samp{gnu-libc}, and
-@samp{gdb}.
-
-Do not use a @samp{--with} option to specify the file name to use to
-find certain files. That is outside the scope of what @samp{--with}
-options are for.
-
-@item --nfp
-The target machine has no floating point processor.
-
-@item --gas
-The target machine assembler is GAS, the GNU assembler.
-This is obsolete; users should use @samp{--with-gnu-as} instead.
-
-@item --x
-The target machine has the X Window System installed.
-This is obsolete; users should use @samp{--with-x} instead.
-@end table
-
-All @code{configure} scripts should accept all of these ``detail''
-options, whether or not they make any difference to the particular
-package at hand. In particular, they should accept any option that
-starts with @samp{--with-} or @samp{--enable-}. This is so users will
-be able to configure an entire GNU source tree at once with a single set
-of options.
-
-You will note that the categories @samp{--with-} and @samp{--enable-}
-are narrow: they @strong{do not} provide a place for any sort of option
-you might think of. That is deliberate. We want to limit the possible
-configuration options in GNU software. We do not want GNU programs to
-have idiosyncratic configuration options.
-
-Packages that perform part of compilation may support cross-compilation.
-In such a case, the host and target machines for the program may be
-different. The @code{configure} script should normally treat the
-specified type of system as both the host and the target, thus producing
-a program which works for the same type of machine that it runs on.
-
-The way to build a cross-compiler, cross-assembler, or what have you, is
-to specify the option @samp{--host=@var{hosttype}} when running
-@code{configure}. This specifies the host system without changing the
-type of target system. The syntax for @var{hosttype} is the same as
-described above.
-
-Bootstrapping a cross-compiler requires compiling it on a machine other
-than the host it will run on. Compilation packages accept a
-configuration option @samp{--build=@var{hosttype}} for specifying the
-configuration on which you will compile them, in case that is different
-from the host.
-
-Programs for which cross-operation is not meaningful need not accept the
-@samp{--host} option, because configuring an entire operating system for
-cross-operation is not a meaningful thing.
-
-Some programs have ways of configuring themselves automatically. If
-your program is set up to do this, your @code{configure} script can simply
-ignore most of its arguments.
-
-@node Source Language
-@chapter Using Languages Other Than C
-
-Using a language other than C is like using a non-standard feature: it
-will cause trouble for users. Even if GCC supports the other language,
-users may find it inconvenient to have to install the compiler for that
-other language in order to build your program. So please write in C.
-
-There are three exceptions for this rule:
-
-@itemize @bullet
-@item
-It is okay to use a special language if the same program contains an
-interpreter for that language.
-
-Thus, it is not a problem that GNU Emacs contains code written in Emacs
-Lisp, because it comes with a Lisp interpreter.
-
-@item
-It is okay to use another language in a tool specifically intended for
-use with that language.
-
-This is okay because the only people who want to build the tool will be
-those who have installed the other language anyway.
-
-@item
-If an application is not of extremely widespread interest, then perhaps
-it's not important if the application is inconvenient to install.
-@end itemize
-
-@node Formatting
-@chapter Formatting Your Source Code
-
-It is important to put the open-brace that starts the body of a C
-function in column zero, and avoid putting any other open-brace or
-open-parenthesis or open-bracket in column zero. Several tools look
-for open-braces in column zero to find the beginnings of C functions.
-These tools will not work on code not formatted that way.
-
-It is also important for function definitions to start the name of the
-function in column zero. This helps people to search for function
-definitions, and may also help certain tools recognize them. Thus,
-the proper format is this:
-
-@example
-static char *
-concat (s1, s2) /* Name starts in column zero here */
- char *s1, *s2;
-@{ /* Open brace in column zero here */
- @dots{}
-@}
-@end example
+You can freely assume any reasonably standard facilities in the C
+language, libraries or kernel, because we will find it necessary to
+support these facilities in the full GNU system, whether or not we
+have already done so. The fact that there may exist kernels or C
+compilers that lack these facilities is irrelevant as long as the GNU
+kernel and C compiler support them.
-@noindent
-or, if you want to use @sc{ANSI} C, format the definition like this:
+It remains necessary to worry about differences among cpu types, such
+as the difference in byte ordering and alignment restrictions. It's
+unlikely that 16-bit machines will ever be supported by GNU, so there
+is no point in spending any time to consider the possibility that an
+@code{int} will be less than 32 bits.
-@example
-static char *
-concat (char *s1, char *s2)
-@{
- @dots{}
-@}
-@end example
+You can assume that all pointers have the same format, regardless
+of the type they point to, and that this is really an integer.
+There are some weird machines where this isn't true, but they aren't
+important; don't waste time catering to them. Besides, eventually
+we will put function prototypes into all GNU programs, and that will
+probably make your program work even on weird machines.
-In @sc{ANSI} C, if the arguments don't fit nicely on one line,
-split it like this:
+Since some important machines (including the 68000) are big-endian,
+it is important not to assume that the address of an @code{int} object
+is also the address of its least-significant byte. Thus, don't
+make the following mistake:
@example
-int
-lots_of_args (int an_integer, long a_long, short a_short,
- double a_double, float a_float)
+int c;
@dots{}
+while ((c = getchar()) != EOF)
+ write(file_descriptor, &c, 1);
@end example
-For the body of the function, we prefer code formatted like this:
-
-@example
-if (x < foo (y, z))
- haha = bar[4] + 5;
-else
- @{
- while (z)
- @{
- haha += foo (z, z);
- z--;
- @}
- return ++x + bar ();
- @}
-@end example
-
-We find it easier to read a program when it has spaces before the
-open-parentheses and after the commas. Especially after the commas.
-
-When you split an expression into multiple lines, split it
-before an operator, not after one. Here is the right way:
-
-@example
-if (foo_this_is_long && bar > win (x, y, z)
- && remaining_condition)
-@end example
-
-Try to avoid having two operators of different precedence at the same
-level of indentation. For example, don't write this:
-
-@example
-mode = (inmode[j] == VOIDmode
- || GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j])
- ? outmode[j] : inmode[j]);
-@end example
-
-Instead, use extra parentheses so that the indentation shows the nesting:
-
-@example
-mode = ((inmode[j] == VOIDmode
- || (GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j])))
- ? outmode[j] : inmode[j]);
-@end example
+You can assume that it is reasonable to use a meg of memory. Don't
+strain to reduce memory usage unless it can get to that level. If
+your program creates complicated data structures, just make them in
+core and give a fatal error if @code{malloc} returns zero.
-Insert extra parentheses so that Emacs will indent the code properly.
-For example, the following indentation looks nice if you do it by hand,
-but Emacs would mess it up:
+If a program works by lines and could be applied to arbitrary
+user-supplied input files, it should keep only a line in memory, because
+this is not very hard and users will want to be able to operate on input
+files that are bigger than will fit in core all at once.
-@example
-v = rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
- + rup->ru_stime.tv_sec*1000 + rup->ru_stime.tv_usec/1000;
-@end example
+@node Program Behavior
+@chapter Program Behavior for All Programs
-But adding a set of parentheses solves the problem:
+This @value{CHAPTER} describes how to write robust software. It also
+describes general standards for error messages, the command line interface,
+and how libraries should behave.
-@example
-v = (rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
- + rup->ru_stime.tv_sec*1000 + rup->ru_stime.tv_usec/1000);
-@end example
+@menu
+* Semantics:: Writing Robust Programs
+* Libraries:: Library Behavior
+* Errors:: Formatting Error Messages
+* User Interfaces:: Standards for Command Line Interfaces
+@end menu
-Format do-while statements like this:
+@node Semantics
+@section Writing Robust Programs
-@example
-do
- @{
- a = foo (a);
- @}
-while (a > 0);
-@end example
+Avoid arbitrary limits on the length or number of @emph{any} data
+structure, including file names, lines, files, and symbols, by allocating
+all data structures dynamically. In most Unix utilities, ``long lines
+are silently truncated''. This is not acceptable in a GNU utility.
-Please use formfeed characters (control-L) to divide the program into
-pages at logical places (but not within a function). It does not matter
-just how long the pages are, since they do not have to fit on a printed
-page. The formfeeds should appear alone on lines by themselves.
+Utilities reading files should not drop NUL characters, or any other
+nonprinting characters @emph{including those with codes above 0177}. The
+only sensible exceptions would be utilities specifically intended for
+interface to certain types of printers that can't handle those characters.
+Check every system call for an error return, unless you know you wish to
+ignore errors. Include the system error text (from @code{perror} or
+equivalent) in @emph{every} error message resulting from a failing
+system call, as well as the name of the file if any and the name of the
+utility. Just ``cannot open foo.c'' or ``stat failed'' is not
+sufficient.
-@node Comments
-@chapter Commenting Your Work
+Check every call to @code{malloc} or @code{realloc} to see if it
+returned zero. Check @code{realloc} even if you are making the block
+smaller; in a system that rounds block sizes to a power of 2,
+@code{realloc} may get a different block if you ask for less space.
-Every program should start with a comment saying briefly what it is for.
-Example: @samp{fmt - filter for simple filling of text}.
+In Unix, @code{realloc} can destroy the storage block if it returns
+zero. GNU @code{realloc} does not have this bug: if it fails, the
+original block is unchanged. Feel free to assume the bug is fixed. If
+you wish to run your program on Unix, and wish to avoid lossage in this
+case, you can use the GNU @code{malloc}.
-Please put a comment on each function saying what the function does,
-what sorts of arguments it gets, and what the possible values of
-arguments mean and are used for. It is not necessary to duplicate in
-words the meaning of the C argument declarations, if a C type is being
-used in its customary fashion. If there is anything nonstandard about
-its use (such as an argument of type @code{char *} which is really the
-address of the second character of a string, not the first), or any
-possible values that would not work the way one would expect (such as,
-that strings containing newlines are not guaranteed to work), be sure
-to say so.
+You must expect @code{free} to alter the contents of the block that was
+freed. Anything you want to fetch from the block, you must fetch before
+calling @code{free}.
-Also explain the significance of the return value, if there is one.
+If @code{malloc} fails in a noninteractive program, make that a fatal
+error. In an interactive program (one that reads commands from the
+user), it is better to abort the command and return to the command
+reader loop. This allows the user to kill other processes to free up
+virtual memory, and then try the command again.
-Please put two spaces after the end of a sentence in your comments, so
-that the Emacs sentence commands will work. Also, please write
-complete sentences and capitalize the first word. If a lower-case
-identifier comes at the beginning of a sentence, don't capitalize it!
-Changing the spelling makes it a different identifier. If you don't
-like starting a sentence with a lower case letter, write the sentence
-differently (e.g., ``The identifier lower-case is @dots{}'').
+Use @code{getopt_long} to decode arguments, unless the argument syntax
+makes this unreasonable.
-The comment on a function is much clearer if you use the argument
-names to speak about the argument values. The variable name itself
-should be lower case, but write it in upper case when you are speaking
-about the value rather than the variable itself. Thus, ``the inode
-number NODE_NUM'' rather than ``an inode''.
+When static storage is to be written in during program execution, use
+explicit C code to initialize it. Reserve C initialized declarations
+for data that will not be changed.
+@c ADR: why?
-There is usually no purpose in restating the name of the function in
-the comment before it, because the reader can see that for himself.
-There might be an exception when the comment is so long that the function
-itself would be off the bottom of the screen.
+Try to avoid low-level interfaces to obscure Unix data structures (such
+as file directories, utmp, or the layout of kernel memory), since these
+are less likely to work compatibly. If you need to find all the files
+in a directory, use @code{readdir} or some other high-level interface.
+These will be supported compatibly by GNU.
-There should be a comment on each static variable as well, like this:
+By default, the GNU system will provide the signal handling functions of
+@sc{BSD} and of @sc{POSIX}. So GNU software should be written to use
+these.
-@example
-/* Nonzero means truncate lines in the display;
- zero means continue them. */
-int truncate_lines;
-@end example
+In error checks that detect ``impossible'' conditions, just abort.
+There is usually no point in printing any message. These checks
+indicate the existence of bugs. Whoever wants to fix the bugs will have
+to read the source code and run a debugger. So explain the problem with
+comments in the source. The relevant data will be in variables, which
+are easy to examine with the debugger, so there is no point moving them
+elsewhere.
-Every @samp{#endif} should have a comment, except in the case of short
-conditionals (just a few lines) that are not nested. The comment should
-state the condition of the conditional that is ending, @emph{including
-its sense}. @samp{#else} should have a comment describing the condition
-@emph{and sense} of the code that follows. For example:
+Do not use a count of errors as the exit status for a program.
+@emph{That does not work}, because exit status values are limited to 8
+bits (0 through 255). A single run of the program might have 256
+errors; if you try to return 256 as the exit status, the parent process
+will see 0 as the status, and it will appear that the program succeeded.
-@example
-#ifdef foo
- @dots{}
-#else /* not foo */
- @dots{}
-#endif /* not foo */
-@end example
+If you make temporary files, check the @code{TMPDIR} environment
+variable; if that variable is defined, use the specified directory
+instead of @file{/tmp}.
-@noindent
-but, by contrast, write the comments this way for a @samp{#ifndef}:
+@node Libraries
+@section Library Behavior
-@example
-#ifndef foo
- @dots{}
-#else /* foo */
- @dots{}
-#endif /* foo */
-@end example
+Try to make library functions reentrant. If they need to do dynamic
+storage allocation, at least try to avoid any nonreentrancy aside from
+that of @code{malloc} itself.
+Here are certain name conventions for libraries, to avoid name
+conflicts.
-@node Syntactic Conventions
-@chapter Clean Use of C Constructs
+Choose a name prefix for the library, more than two characters long.
+All external function and variable names should start with this
+prefix. In addition, there should only be one of these in any given
+library member. This usually means putting each one in a separate
+source file.
-Please explicitly declare all arguments to functions.
-Don't omit them just because they are @code{int}s.
+An exception can be made when two external symbols are always used
+together, so that no reasonable program could use one without the
+other; then they can both go in the same file.
-Declarations of external functions and functions to appear later in the
-source file should all go in one place near the beginning of the file
-(somewhere before the first function definition in the file), or else
-should go in a header file. Don't put @code{extern} declarations inside
-functions.
+External symbols that are not documented entry points for the user
+should have names beginning with @samp{_}. They should also contain
+the chosen name prefix for the library, to prevent collisions with
+other libraries. These can go in the same files with user entry
+points if you like.
-It used to be common practice to use the same local variables (with
-names like @code{tem}) over and over for different values within one
-function. Instead of doing this, it is better declare a separate local
-variable for each distinct purpose, and give it a name which is
-meaningful. This not only makes programs easier to understand, it also
-facilitates optimization by good compilers. You can also move the
-declaration of each local variable into the smallest scope that includes
-all its uses. This makes the program even cleaner.
+Static functions and variables can be used as you like and need not
+fit any naming convention.
-Don't use local variables or parameters that shadow global identifiers.
-Don't declare multiple variables in one declaration that spans lines.
-Start a new declaration on each line, instead. For example, instead
-of this:
+
+@node Errors
+@section Formatting Error Messages
+
+Error messages from compilers should look like this:
@example
-int foo,
- bar;
+@var{source-file-name}:@var{lineno}: @var{message}
@end example
-@noindent
-write either this:
+Error messages from other noninteractive programs should look like this:
@example
-int foo, bar;
+@var{program}:@var{source-file-name}:@var{lineno}: @var{message}
@end example
@noindent
-or this:
+when there is an appropriate source file, or like this:
@example
-int foo;
-int bar;
+@var{program}: @var{message}
@end example
@noindent
-(If they are global variables, each should have a comment preceding it
-anyway.)
+when there is no relevant source file.
-When you have an @code{if}-@code{else} statement nested in another
-@code{if} statement, always put braces around the @code{if}-@code{else}.
-Thus, never write like this:
+In an interactive program (one that is reading commands from a
+terminal), it is better not to include the program name in an error
+message. The place to indicate which program is running is in the
+prompt or with the screen layout. (When the same program runs with
+input from a source other than a terminal, it is not interactive and
+would do best to print error messages using the noninteractive style.)
-@example
-if (foo)
- if (bar)
- win ();
- else
- lose ();
-@end example
+The string @var{message} should not begin with a capital letter when
+it follows a program name and/or file name. Also, it should not end
+with a period.
-@noindent
-always like this:
+Error messages from interactive programs, and other messages such as
+usage messages, should start with a capital letter. But they should not
+end with a period.
-@example
-if (foo)
- @{
- if (bar)
- win ();
- else
- lose ();
- @}
-@end example
-If you have an @code{if} statement nested inside of an @code{else}
-statement, either write @code{else if} on one line, like this,
+@node User Interfaces
+@section Standards for Command Line Interfaces
-@example
-if (foo)
- @dots{}
-else if (bar)
- @dots{}
-@end example
+Please don't make the behavior of a utility depend on the name used
+to invoke it. It is useful sometimes to make a link to a utility
+with a different name, and that should not change what it does.
-@noindent
-with its @code{then}-part indented like the preceding @code{then}-part,
-or write the nested @code{if} within braces like this:
+Instead, use a run time option or a compilation switch or both
+to select among the alternate behaviors.
-@example
-if (foo)
- @dots{}
-else
- @{
- if (bar)
- @dots{}
- @}
-@end example
+Likewise, please don't make the behavior of the program depend on the
+type of output device it is used with. Device independence is an
+important principle of the system's design; do not compromise it
+merely to save someone from typing an option now and then.
-Don't declare both a structure tag and variables or typedefs in the
-same declaration. Instead, declare the structure tag separately
-and then use it to declare the variables or typedefs.
+If you think one behavior is most useful when the output is to a
+terminal, and another is most useful when the output is a file or a
+pipe, then it is usually best to make the default behavior the one that
+is useful with output to a terminal, and have an option for the other
+behavior.
-Try to avoid assignments inside @code{if}-conditions. For example,
-don't write this:
+Compatibility requires certain programs to depend on the type of output
+device. It would be disastrous if @code{ls} or @code{sh} did not do so
+in the way all users expect. In some of these cases, we supplement the
+program with a preferred alternate version that does not depend on the
+output device type. For example, we provide a @code{dir} program much
+like @code{ls} except that its default output format is always
+multi-column format.
-@example
-if ((foo = (char *) malloc (sizeof *foo)) == 0)
- fatal ("virtual memory exhausted");
-@end example
+It is a good idea to follow the @sc{POSIX} guidelines for the
+command-line options of a program. The easiest way to do this is to use
+@code{getopt} to parse them. Note that the GNU version of @code{getopt}
+will normally permit options anywhere among the arguments unless the
+special argument @samp{--} is used. This is not what @sc{POSIX}
+specifies; it is a GNU extension.
-@noindent
-instead, write this:
+Please define long-named options that are equivalent to the
+single-letter Unix-style options. We hope to make GNU more user
+friendly this way. This is easy to do with the GNU function
+@code{getopt_long}.
-@example
-foo = (char *) malloc (sizeof *foo);
-if (foo == 0)
- fatal ("virtual memory exhausted");
-@end example
+One of the advantages of long-named options is that they can be
+consistent from program to program. For example, users should be able
+to expect the ``verbose'' option of any GNU program which has one, to be
+spelled precisely @samp{--verbose}. To achieve this uniformity, look at
+the table of common long-option names when you choose the option names
+for your program. The table appears below.
-Don't make the program ugly to placate @code{lint}. Please don't insert any
-casts to @code{void}. Zero without a cast is perfectly fine as a null
-pointer constant.
+If you use names not already in the table, please send
+@samp{gnu@@prep.ai.mit.edu} a list of them, with their meanings, so we
+can update the table.
-@node Names
-@chapter Naming Variables, Functions, and Files
+It is usually a good idea for file names given as ordinary arguments
+to be input files only; any output files would be specified using
+options (preferably @samp{-o}). Even if you allow an output file name
+as an ordinary argument for compatibility, try to provide a suitable
+option as well. This will lead to more consistency among GNU
+utilities, so that there are fewer idiosyncracies for users to
+remember.
-Please use underscores to separate words in a name, so that the Emacs
-word commands can be useful within them. Stick to lower case; reserve
-upper case for macros and @code{enum} constants, and for name-prefixes
-that follow a uniform convention.
+Programs should support an option @samp{--version} which prints the
+program's version number on standard output and exits successfully, and
+an option @samp{--help} which prints option usage information on
+standard output and exits successfully. These options should inhibit
+the normal function of the command; they should do nothing except print
+the requested information.
-For example, you should use names like @code{ignore_space_change_flag};
-don't use names like @code{iCantReadThis}.
+@c Please leave newlines between items in this table; it's much easier
+@c to update when it isn't completely squashed together and unreadable.
+@c When there is more than one short option for a long option name, put
+@c a semicolon between the lists of the programs that use them, not a
+@c period. --friedman
-Variables that indicate whether command-line options have been
-specified should be named after the meaning of the option, not after
-the option-letter. A comment should state both the exact meaning of
-the option and its letter. For example,
+Here is the table of long options used by GNU programs.
-@example
-/* Ignore changes in horizontal whitespace (-b). */
-int ignore_space_change_flag;
-@end example
+@table @samp
-When you want to define names with constant integer values, use
-@code{enum} rather than @samp{#define}. GDB knows about enumeration
-constants.
+@item after-date
+@samp{-N} in @code{tar}.
-Use file names of 14 characters or less, to avoid creating gratuitous
-problems on System V. You can use the program @code{doschk} to test for
-this. @code{doschk} also tests for potential name conflicts if the
-files were loaded onto an MS-DOS file system---something you may or may
-not care about.
+@item all
+@samp{-a} in @code{du}, @code{ls}, @code{nm}, @code{stty}, @code{uname},
+and @code{unexpand}.
-In general, use @samp{-} to separate words in file names, not @samp{_}.
-Make all letters in file names be lower case, except when following
-specific conventions that call for upper case in certain kinds of names.
-Conventional occasions for using upper case letters in file names
-include @file{Makefile}, @file{ChangeLog}, @file{COPYING} and
-@file{README}. It is common to name other @file{README}-like
-documentation files in all upper case just like @file{README}.
+@item all-text
+@samp{-a} in @code{diff}.
-@node Using Extensions
-@chapter Using Non-standard Features
+@item almost-all
+@samp{-A} in @code{ls}.
-Many GNU facilities that already exist support a number of convenient
-extensions over the comparable Unix facilities. Whether to use these
-extensions in implementing your program is a difficult question.
+@item append
+@samp{-a} in @code{etags}, @code{tee}, @code{time};
+@samp{-r} in @code{tar}.
-On the one hand, using the extensions can make a cleaner program.
-On the other hand, people will not be able to build the program
-unless the other GNU tools are available. This might cause the
-program to work on fewer kinds of machines.
+@item archive
+@samp{-a} in @code{cp}.
-With some extensions, it might be easy to provide both alternatives.
-For example, you can define functions with a ``keyword'' @code{INLINE}
-and define that as a macro to expand into either @code{inline} or
-nothing, depending on the compiler.
+@item archive-name
+@samp{-n} in @code{shar}.
-In general, perhaps it is best not to use the extensions if you can
-straightforwardly do without them, but to use the extensions if they
-are a big improvement.
+@item arglength
+@samp{-l} in @code{m4}.
-An exception to this rule are the large, established programs (such as
-Emacs) which run on a great variety of systems. Such programs would
-be broken by use of GNU extensions.
+@item ascii
+@samp{-a} in @code{diff}.
-Another exception is for programs that are used as part of
-compilation: anything that must be compiled with other compilers in
-order to bootstrap the GNU compilation facilities. If these require
-the GNU compiler, then no one can compile them without having them
-installed already. That would be no good.
+@item assign
+@samp{-v} in @code{gawk}.
-Since most computer systems do not yet implement @sc{ANSI} C, using the
-@sc{ANSI} C features is effectively using a GNU extension, so the
-same considerations apply. (Except for @sc{ANSI} features that we
-discourage, such as trigraphs---don't ever use them.)
+@item assume-new
+@samp{-W} in Make.
+@item assume-old
+@samp{-o} in Make.
-@node System Functions
-@chapter Calling System Functions
+@item auto-check
+@samp{-a} in @code{recode}.
-C implementations differ substantially. ANSI C reduces but does not
-eliminate the incompatibilities; meanwhile, many users wish to compile
-GNU software with pre-ANSI compilers. This chapter gives
-recommendations for how to use the more or less standard C library
-functions to avoid unnecessary loss of portability.
+@item auto-pager
+@samp{-a} in @code{wdiff}.
-@itemize @bullet
-@item
-Don't use the value of @code{sprintf}. It returns the number of
-characters written on some systems, but not on all systems.
+@item auto-reference
+@samp{-A} in @code{ptx}.
-@item
-Don't declare system functions explicitly.
+@item avoid-wraps
+@samp{-n} in @code{wdiff}.
-Almost any declaration for a system function is wrong on some system.
-To minimize conflicts, leave it to the system header files to declare
-system functions. If the headers don't declare a function, let it
-remain undeclared.
+@item backward-search
+@samp{-B} in @code{ctags}.
-While it may seem unclean to use a function without declaring it, in
-practice this works fine for most system library functions on the
-systems where this really happens. The problem is only theoretical. By
-contrast, actual declarations have frequently caused actual conflicts.
+@item basename
+@samp{-f} in @code{shar}.
-@item
-If you must declare a system function, don't specify the argument types.
-Use an old-style declaration, not an ANSI prototype. The more you
-specify about the function, the more likely a conflict.
+@item batch
+Used in GDB.
-@item
-In particular, don't unconditionally declare @code{malloc} or
-@code{realloc}.
+@item baud
+Used in GDB.
-Most GNU programs use those functions just once, in functions
-conventionally named @code{xmalloc} and @code{xrealloc}. These
-functions call @code{malloc} and @code{realloc}, respectively, and
-check the results.
+@item before
+@samp{-b} in @code{tac}.
-Because @code{xmalloc} and @code{xrealloc} are defined in your program,
-you can declare them in other files without any risk of type conflict.
+@item binary
+@samp{-b} in @code{cpio} and @code{diff}.
-On most systems, @code{int} is the same length as a pointer; thus, the
-calls to @code{malloc} and @code{realloc} work fine. For the few
-exceptional systems (mostly 64-bit machines), you can use
-@strong{conditionalized} declarations of @code{malloc} and
-@code{realloc}---or put these declarations in configuration files
-specific to those systems.
+@item bits-per-code
+@samp{-b} in @code{shar}.
-@item
-The string functions require special treatment. Some Unix systems have
-a header file @file{string.h}; other have @file{strings.h}. Neither
-file name is portable. There are two things you can do: use Autoconf to
-figure out which file to include, or don't include either file.
+@item block-size
+Used in @code{cpio} and @code{tar}.
-@item
-If you don't include either strings file, you can't get declarations for
-the string functions from the header file in the usual way.
+@item blocks
+@samp{-b} in @code{head} and @code{tail}.
-That causes less of a problem than you might think. The newer ANSI
-string functions are off-limits anyway because many systems still don't
-support them. The string functions you can use are these:
+@item break-file
+@samp{-b} in @code{ptx}.
-@example
-strcpy strncpy strcat strncat
-strlen strcmp strncmp
-strchr strrchr
-@end example
+@item brief
+Used in various programs to make output shorter.
-The copy and concatenate functions work fine without a declaration as
-long as you don't use their values. Using their values without a
-declaration fails on systems where the width of a pointer differs from
-the width of @code{int}, and perhaps in other cases. It is trivial to
-avoid using their values, so do that.
+@item bytes
+@samp{-c} in @code{head}, @code{split}, and @code{tail}.
-The compare functions and @code{strlen} work fine without a declaration
-on most systems, possibly all the ones that GNU software runs on.
-You may find it necessary to declare them @strong{conditionally} on a
-few systems.
+@item c@t{++}
+@samp{-C} in @code{etags}.
-The search functions must be declared to return @code{char *}. Luckily,
-there is no variation in the data type they return. But there is
-variation in their names. Some systems give these functions the names
-@code{index} and @code{rindex}; other systems use the names
-@code{strchr} and @code{strrchr}. Some systems support both pairs of
-names, but neither pair works on all systems.
+@item catenate
+@samp{-A} in @code{tar}.
-You should pick a single pair of names and use it throughout your
-program. (Nowadays, it is better to choose @code{strchr} and
-@code{strrchr}.) Declare both of those names as functions returning
-@code{char *}. On systems which don't support those names, define them
-as macros in terms of the other pair. For example, here is what to put
-at the beginning of your file (or in a header) if you want to use the
-names @code{strchr} and @code{strrchr} throughout:
+@item cd
+Used in various programs to specify the directory to use.
-@example
-#ifndef HAVE_STRCHR
-#define strchr index
-#endif
-#ifndef HAVE_STRRCHR
-#define strrchr rindex
-#endif
+@item changes
+@samp{-c} in @code{chgrp} and @code{chown}.
-char *strchr ();
-char *strrchr ();
-@end example
-@end itemize
+@item classify
+@samp{-F} in @code{ls}.
-Here we assume that @code{HAVE_STRCHR} and @code{HAVE_STRRCHR} are
-macros defined in systems where the corresponding functions exist.
-One way to get them properly defined is to use Autoconf.
+@item colons
+@samp{-c} in @code{recode}.
-@node Semantics
-@chapter Program Behavior for All Programs
+@item command
+@samp{-c} in @code{su};
+@samp{-x} in GDB.
-Avoid arbitrary limits on the length or number of @emph{any} data
-structure, including file names, lines, files, and symbols, by allocating
-all data structures dynamically. In most Unix utilities, ``long lines
-are silently truncated''. This is not acceptable in a GNU utility.
+@item compare
+@samp{-d} in @code{tar}.
-Utilities reading files should not drop NUL characters, or any other
-nonprinting characters @emph{including those with codes above 0177}. The
-only sensible exceptions would be utilities specifically intended for
-interface to certain types of printers that can't handle those characters.
+@item compat
+Used in @code{gawk}.
-Check every system call for an error return, unless you know you wish to
-ignore errors. Include the system error text (from @code{perror} or
-equivalent) in @emph{every} error message resulting from a failing
-system call, as well as the name of the file if any and the name of the
-utility. Just ``cannot open foo.c'' or ``stat failed'' is not
-sufficient.
+@item compress
+@samp{-Z} in @code{tar} and @code{shar}.
-Check every call to @code{malloc} or @code{realloc} to see if it
-returned zero. Check @code{realloc} even if you are making the block
-smaller; in a system that rounds block sizes to a power of 2,
-@code{realloc} may get a different block if you ask for less space.
+@item concatenate
+@samp{-A} in @code{tar}.
-In Unix, @code{realloc} can destroy the storage block if it returns
-zero. GNU @code{realloc} does not have this bug: if it fails, the
-original block is unchanged. Feel free to assume the bug is fixed. If
-you wish to run your program on Unix, and wish to avoid lossage in this
-case, you can use the GNU @code{malloc}.
+@item confirmation
+@samp{-w} in @code{tar}.
-You must expect @code{free} to alter the contents of the block that was
-freed. Anything you want to fetch from the block, you must fetch before
-calling @code{free}.
+@item context
+Used in @code{diff}.
-If @code{malloc} fails in a noninteractive program, make that a fatal
-error. In an interactive program (one that reads commands from the
-user), it is better to abort the command and return to the command
-reader loop. This allows the user to kill other processes to free up
-virtual memory, and then try the command again.
+@item copyleft
+@samp{-W copyleft} in @code{gawk}.
-Use @code{getopt_long} to decode arguments, unless the argument syntax
-makes this unreasonable.
+@item copyright
+@samp{-C} in @code{ptx}, @code{recode}, and @code{wdiff};
+@samp{-W copyright} in @code{gawk}.
-When static storage is to be written in during program execution, use
-explicit C code to initialize it. Reserve C initialized declarations
-for data that will not be changed.
+@item core
+Used in GDB.
-Try to avoid low-level interfaces to obscure Unix data structures (such
-as file directories, utmp, or the layout of kernel memory), since these
-are less likely to work compatibly. If you need to find all the files
-in a directory, use @code{readdir} or some other high-level interface.
-These will be supported compatibly by GNU.
+@item count
+@samp{-q} in @code{who}.
-By default, the GNU system will provide the signal handling functions of
-@sc{BSD} and of @sc{POSIX}. So GNU software should be written to use
-these.
+@item count-links
+@samp{-l} in @code{du}.
-In error checks that detect ``impossible'' conditions, just abort.
-There is usually no point in printing any message. These checks
-indicate the existence of bugs. Whoever wants to fix the bugs will have
-to read the source code and run a debugger. So explain the problem with
-comments in the source. The relevant data will be in variables, which
-are easy to examine with the debugger, so there is no point moving them
-elsewhere.
+@item create
+Used in @code{tar} and @code{cpio}.
-Do not use a count of errors as the exit status for a program.
-@emph{That does not work}, because exit status values are limited to 8
-bits (0 through 255). A single run of the program might have 256
-errors; if you try to return 256 as the exit status, the parent process
-will see 0 as the status, and it will appear that the program succeeded.
+@item cut-mark
+@samp{-c} in @code{shar}.
-If you make temporary files, check the @code{TMPDIR} environment
-variable; if that variable is defined, use the specified directory
-instead of @file{/tmp}.
+@item cxref
+@samp{-x} in @code{ctags}.
-@node Errors
-@chapter Formatting Error Messages
+@item date
+@samp{-d} in @code{touch}.
-Error messages from compilers should look like this:
+@item debug
+@samp{-d} in Make and @code{m4};
+@samp{-t} in Bison.
-@example
-@var{source-file-name}:@var{lineno}: @var{message}
-@end example
+@item define
+@samp{-D} in @code{m4}.
-Error messages from other noninteractive programs should look like this:
+@item defines
+@samp{-d} in Bison and @code{ctags}.
-@example
-@var{program}:@var{source-file-name}:@var{lineno}: @var{message}
-@end example
+@item delete
+@samp{-D} in @code{tar}.
-@noindent
-when there is an appropriate source file, or like this:
+@item dereference
+@samp{-L} in @code{chgrp}, @code{chown}, @code{cpio}, @code{du},
+@code{ls}, and @code{tar}.
-@example
-@var{program}: @var{message}
-@end example
+@item dereference-args
+@samp{-D} in @code{du}.
-@noindent
-when there is no relevant source file.
+@item diacritics
+@samp{-d} in @code{recode}.
-In an interactive program (one that is reading commands from a
-terminal), it is better not to include the program name in an error
-message. The place to indicate which program is running is in the
-prompt or with the screen layout. (When the same program runs with
-input from a source other than a terminal, it is not interactive and
-would do best to print error messages using the noninteractive style.)
+@item dictionary-order
+@samp{-d} in @code{look}.
-The string @var{message} should not begin with a capital letter when
-it follows a program name and/or file name. Also, it should not end
-with a period.
+@item diff
+@samp{-d} in @code{tar}.
-Error messages from interactive programs, and other messages such as
-usage messages, should start with a capital letter. But they should not
-end with a period.
+@item digits
+@samp{-n} in @code{csplit}.
+@item directory
+Specify the directory to use, in various programs. In @code{ls}, it
+means to show directories themselves rather than their contents. In
+@code{rm} and @code{ln}, it means to not treat links to directories
+specially.
-@node Libraries
-@chapter Library Behavior
+@item discard-all
+@samp{-x} in @code{strip}.
-Try to make library functions reentrant. If they need to do dynamic
-storage allocation, at least try to avoid any nonreentrancy aside from
-that of @code{malloc} itself.
+@item discard-locals
+@samp{-X} in @code{strip}.
-Here are certain name conventions for libraries, to avoid name
-conflicts.
+@item dry-run
+@samp{-n} in Make.
-Choose a name prefix for the library, more than two characters long.
-All external function and variable names should start with this
-prefix. In addition, there should only be one of these in any given
-library member. This usually means putting each one in a separate
-source file.
+@item ed
+@samp{-e} in @code{diff}.
-An exception can be made when two external symbols are always used
-together, so that no reasonable program could use one without the
-other; then they can both go in the same file.
+@item elide-empty-files
+@samp{-z} in @code{csplit}.
-External symbols that are not documented entry points for the user
-should have names beginning with @samp{_}. They should also contain
-the chosen name prefix for the library, to prevent collisions with
-other libraries. These can go in the same files with user entry
-points if you like.
+@item end-delete
+@samp{-x} in @code{wdiff}.
-Static functions and variables can be used as you like and need not
-fit any naming convention.
+@item end-insert
+@samp{-z} in @code{wdiff}.
+@item entire-new-file
+@samp{-N} in @code{diff}.
-@node Portability
-@chapter Portability As It Applies to GNU
+@item environment-overrides
+@samp{-e} in Make.
-Much of what is called ``portability'' in the Unix world refers to
-porting to different Unix versions. This is a secondary consideration
-for GNU software, because its primary purpose is to run on top of one
-and only one kernel, the GNU kernel, compiled with one and only one C
-compiler, the GNU C compiler. The amount and kinds of variation among
-GNU systems on different cpu's will be like the variation among Berkeley
-4.3 systems on different cpu's.
+@item eof
+@samp{-e} in @code{xargs}.
-All users today run GNU software on non-GNU systems. So supporting a
-variety of non-GNU systems is desirable; simply not paramount.
-The easiest way to achieve portability to a reasonable range of systems
-is to use Autoconf. It's unlikely that your program needs to know more
-information about the host machine than Autoconf can provide, simply
-because most of the programs that need such knowledge have already been
-written.
+@item epoch
+Used in GDB.
-It is difficult to be sure exactly what facilities the GNU kernel
-will provide, since it isn't finished yet. Therefore, assume you can
-use anything in 4.3; just avoid using the format of semi-internal data
-bases (e.g., directories) when there is a higher-level alternative
-(@code{readdir}).
+@item error-limit
+Used in @code{makeinfo}.
-You can freely assume any reasonably standard facilities in the C
-language, libraries or kernel, because we will find it necessary to
-support these facilities in the full GNU system, whether or not we
-have already done so. The fact that there may exist kernels or C
-compilers that lack these facilities is irrelevant as long as the GNU
-kernel and C compiler support them.
+@item error-output
+@samp{-o} in @code{m4}.
-It remains necessary to worry about differences among cpu types, such
-as the difference in byte ordering and alignment restrictions. It's
-unlikely that 16-bit machines will ever be supported by GNU, so there
-is no point in spending any time to consider the possibility that an
-int will be less than 32 bits.
+@item escape
+@samp{-b} in @code{ls}.
-You can assume that all pointers have the same format, regardless
-of the type they point to, and that this is really an integer.
-There are some weird machines where this isn't true, but they aren't
-important; don't waste time catering to them. Besides, eventually
-we will put function prototypes into all GNU programs, and that will
-probably make your program work even on weird machines.
+@item exclude-from
+@samp{-X} in @code{tar}.
-Since some important machines (including the 68000) are big-endian,
-it is important not to assume that the address of an @code{int} object
-is also the address of its least-significant byte. Thus, don't
-make the following mistake:
+@item exec
+Used in GDB.
-@example
-int c;
-@dots{}
-while ((c = getchar()) != EOF)
- write(file_descriptor, &c, 1);
-@end example
+@item exit
+@samp{-x} in @code{xargs}.
-You can assume that it is reasonable to use a meg of memory. Don't
-strain to reduce memory usage unless it can get to that level. If
-your program creates complicated data structures, just make them in
-core and give a fatal error if malloc returns zero.
+@item exit-0
+@samp{-e} in @code{unshar}.
-If a program works by lines and could be applied to arbitrary
-user-supplied input files, it should keep only a line in memory, because
-this is not very hard and users will want to be able to operate on input
-files that are bigger than will fit in core all at once.
+@item expand-tabs
+@samp{-t} in @code{diff}.
+@item expression
+@samp{-e} in @code{sed}.
-@node User Interfaces
-@chapter Standards for Command Line Interfaces
+@item extern-only
+@samp{-g} in @code{nm}.
-Please don't make the behavior of a utility depend on the name used
-to invoke it. It is useful sometimes to make a link to a utility
-with a different name, and that should not change what it does.
+@item extract
+@samp{-i} in @code{cpio};
+@samp{-x} in @code{tar}.
-Instead, use a run time option or a compilation switch or both
-to select among the alternate behaviors.
+@item faces
+@samp{-f} in @code{finger}.
-Likewise, please don't make the behavior of the program depend on the
-type of output device it is used with. Device independence is an
-important principle of the system's design; do not compromise it
-merely to save someone from typing an option now and then.
+@item fast
+@samp{-f} in @code{su}.
-If you think one behavior is most useful when the output is to a
-terminal, and another is most useful when the output is a file or a
-pipe, then it is usually best to make the default behavior the one that
-is useful with output to a terminal, and have an option for the other
-behavior.
+@item fatal-warnings
+@samp{-E} in @code{m4}.
-Compatibility requires certain programs to depend on the type of output
-device. It would be disastrous if @code{ls} or @code{sh} did not do so
-in the way all users expect. In some of these cases, we supplement the
-program with a preferred alternate version that does not depend on the
-output device type. For example, we provide a @code{dir} program much
-like @code{ls} except that its default output format is always
-multi-column format.
+@item file
+@samp{-f} in @code{info}, @code{gawk}, Make, @code{mt}, and @code{tar};
+@samp{-n} in @code{sed};
+@samp{-r} in @code{touch}.
-It is a good idea to follow the @sc{POSIX} guidelines for the
-command-line options of a program. The easiest way to do this is to use
-@code{getopt} to parse them. Note that the GNU version of @code{getopt}
-will normally permit options anywhere among the arguments unless the
-special argument @samp{--} is used. This is not what @sc{POSIX}
-specifies; it is a GNU extension.
+@item field-separator
+@samp{-F} in @code{gawk}.
-Please define long-named options that are equivalent to the
-single-letter Unix-style options. We hope to make GNU more user
-friendly this way. This is easy to do with the GNU function
-@code{getopt_long}.
+@item file-prefix
+@samp{-b} in Bison.
-One of the advantages of long-named options is that they can be
-consistent from program to program. For example, users should be able
-to expect the ``verbose'' option of any GNU program which has one, to be
-spelled precisely @samp{--verbose}. To achieve this uniformity, look at
-the table of common long-option names when you choose the option names
-for your program. The table appears below.
+@item file-type
+@samp{-F} in @code{ls}.
-If you use names not already in the table, please send
-@samp{gnu@@prep.ai.mit.edu} a list of them, with their meanings, so we
-can update the table.
+@item files-from
+@samp{-T} in @code{tar}.
-It is usually a good idea for file names given as ordinary arguments
-to be input files only; any output files would be specified using
-options (preferably @samp{-o}). Even if you allow an output file name
-as an ordinary argument for compatibility, try to provide a suitable
-option as well. This will lead to more consistency among GNU
-utilities, so that there are fewer idiosyncracies for users to
-remember.
+@item fill-column
+Used in @code{makeinfo}.
-Programs should support an option @samp{--version} which prints the
-program's version number on standard output and exits successfully, and
-an option @samp{--help} which prints option usage information on
-standard output and exits successfully. These options should inhibit
-the normal function of the command; they should do nothing except print
-the requested information.
+@item flag-truncation
+@samp{-F} in @code{ptx}.
-@c longopts begin here (keyword for isearch)
-@c Please leave newlines between items in this table; it's much easier
-@c to update when it isn't completely squashed together and unreadable.
-@c When there is more than one short option for a long option name, put
-@c a semicolon between the lists of the programs that use them, not a
-@c period. --friedman
+@item fixed-output-files
+@samp{-y} in Bison.
-@table @samp
+@item follow
+@samp{-f} in @code{tail}.
-@item after-date
-@samp{-N} in @code{tar}.
+@item footnote-style
+Used in @code{makeinfo}.
-@item all
-@samp{-a} in @code{du}, @code{ls}, @code{nm}, @code{stty}, @code{uname},
-and @code{unexpand}.
+@item force
+@samp{-f} in @code{cp}, @code{ln}, @code{mv}, and @code{rm}.
-@item all-text
-@samp{-a} in @code{diff}.
+@item force-prefix
+@samp{-F} in @code{shar}.
-@item almost-all
-@samp{-A} in @code{ls}.
+@item format
+Used in @code{ls}, @code{time}, and @code{ptx}.
-@item append
-@samp{-a} in @code{etags}, @code{tee}, @code{time};
-@samp{-r} in @code{tar}.
+@item freeze-state
+@samp{-F} in @code{m4}.
+
+@item fullname
+Used in GDB.
-@item archive
-@samp{-a} in @code{cp}.
+@item gap-size
+@samp{-g} in @code{ptx}.
-@item archive-name
-@samp{-n} in @code{shar}.
+@item get
+@samp{-x} in @code{tar}.
-@item arglength
-@samp{-l} in @code{m4}.
+@item graphic
+@samp{-i} in @code{ul}.
-@item ascii
-@samp{-a} in @code{diff}.
+@item graphics
+@samp{-g} in @code{recode}.
-@item assign
-@samp{-v} in Gawk.
+@item group
+@samp{-g} in @code{install}.
-@item assume-new
-@samp{-W} in Make.
+@item gzip
+@samp{-z} in @code{tar} and @code{shar}.
-@item assume-old
-@samp{-o} in Make.
+@item hashsize
+@samp{-H} in @code{m4}.
-@item auto-check
-@samp{-a} in @code{recode}.
+@item header
+@samp{-h} in @code{objdump} and @code{recode}
-@item auto-pager
-@samp{-a} in @code{wdiff}.
+@item heading
+@samp{-H} in @code{who}.
-@item auto-reference
-@samp{-A} in @code{ptx}.
+@item help
+Used to ask for brief usage information.
-@item avoid-wraps
-@samp{-n} in @code{wdiff}.
+@item here-delimiter
+@samp{-d} in @code{shar}.
-@item backward-search
-@samp{-B} in @code{ctags}.
+@item hide-control-chars
+@samp{-q} in @code{ls}.
-@item basename
-@samp{-f} in @code{shar}.
+@item idle
+@samp{-u} in @code{who}.
-@item batch
-Used in GDB.
+@item ifdef
+@samp{-D} in @code{diff}.
-@item baud
-Used in GDB.
+@item ignore
+@samp{-I} in @code{ls};
+@samp{-x} in @code{recode}.
-@item before
-@samp{-b} in @code{tac}.
+@item ignore-all-space
+@samp{-w} in @code{diff}.
-@item binary
-@samp{-b} in @code{cpio} and @code{diff}.
+@item ignore-backups
+@samp{-B} in @code{ls}.
-@item bits-per-code
-@samp{-b} in @code{shar}.
+@item ignore-blank-lines
+@samp{-B} in @code{diff}.
-@item block-size
-Used in @code{cpio} and @code{tar}.
+@item ignore-case
+@samp{-f} in @code{look} and @code{ptx};
+@samp{-i} in @code{diff} and @code{wdiff}.
-@item blocks
-@samp{-b} in @code{head} and @code{tail}.
+@item ignore-errors
+@samp{-i} in Make.
-@item break-file
-@samp{-b} in @code{ptx}.
+@item ignore-file
+@samp{-i} in @code{ptx}.
-@item brief
-Used in various programs to make output shorter.
+@item ignore-indentation
+@samp{-I} in @code{etags}.
-@item bytes
-@samp{-c} in @code{head}, @code{split}, and @code{tail}.
+@item ignore-init-file
+@samp{-f} in Oleo.
-@item c@t{++}
-@samp{-C} in @code{etags}.
+@item ignore-interrupts
+@samp{-i} in @code{tee}.
-@item catenate
-@samp{-A} in @code{tar}.
+@item ignore-matching-lines
+@samp{-I} in @code{diff}.
-@item cd
-Used in various programs to specify the directory to use.
+@item ignore-space-change
+@samp{-b} in @code{diff}.
-@item changes
-@samp{-c} in @code{chgrp} and @code{chown}.
+@item ignore-zeros
+@samp{-i} in @code{tar}.
-@item classify
-@samp{-F} in @code{ls}.
+@item include
+@samp{-i} in @code{etags};
+@samp{-I} in @code{m4}.
-@item colons
-@samp{-c} in @code{recode}.
+@item include-dir
+@samp{-I} in Make.
-@item command
-@samp{-c} in @code{su};
-@samp{-x} in GDB.
+@item incremental
+@samp{-G} in @code{tar}.
-@item compare
-@samp{-d} in @code{tar}.
+@item info
+@samp{-i}, @samp{-l}, and @samp{-m} in Finger.
-@item compat
-Used in gawk (no corresponding single-letter option).
+@item initial
+@samp{-i} in @code{expand}.
-@item compress
-@samp{-Z} in @code{tar} and @code{shar}.
+@item initial-tab
+@samp{-T} in @code{diff}.
-@item concatenate
-@samp{-A} in @code{tar}.
+@item inode
+@samp{-i} in @code{ls}.
-@item confirmation
+@item interactive
+@samp{-i} in @code{cp}, @code{ln}, @code{mv}, @code{rm};
+@samp{-e} in @code{m4};
+@samp{-p} in @code{xargs};
@samp{-w} in @code{tar}.
-@item context
-Used in @code{diff}.
+@item intermix-type
+@samp{-p} in @code{shar}.
-@item copyleft
-Used in gawk (no corresponding single-letter option).
+@item jobs
+@samp{-j} in Make.
-@item copyright
-@samp{-C} in @code{ptx}, @code{recode}, and @code{wdiff}.
-Also used in gawk (no corresponding single-letter option).
+@item just-print
+@samp{-n} in Make.
-@item core
-Used in GDB.
+@item keep-going
+@samp{-k} in Make.
-@item count
-@samp{-q} in @code{who}.
+@item keep-files
+@samp{-k} in @code{csplit}.
-@item count-links
-@samp{-l} in @code{du}.
+@item kilobytes
+@samp{-k} in @code{du} and @code{ls}.
-@item create
-Used in @code{tar} and @code{cpio}.
+@item language
+@samp{-l} in @code{etags}.
-@item cut-mark
-@samp{-c} in @code{shar}.
+@item less-mode
+@samp{-l} in @code{wdiff}.
-@item cxref
-@samp{-x} in @code{ctags}.
+@item level-for-gzip
+@samp{-g} in @code{shar}.
-@item date
-@samp{-d} in @code{touch}.
+@item line-bytes
+@samp{-C} in @code{split}.
-@item debug
-@samp{-d} in Make and @code{m4};
-@samp{-t} in Bison.
+@item lines
+Used in @code{split}, @code{head}, and @code{tail}.
-@item define
-@samp{-D} in @code{m4}.
+@item link
+@samp{-l} in @code{cpio}.
-@item defines
-@samp{-d} in Bison and @code{ctags}.
+@item lint
+@itemx lint-old
+Used in @code{gawk}.
-@item delete
-@samp{-D} in @code{tar}.
+@item list
+@samp{-t} in @code{cpio};
+@samp{-l} in @code{recode}.
-@item dereference
-@samp{-L} in @code{chgrp}, @code{chown}, @code{cpio}, @code{du},
-@code{ls}, and @code{tar}.
+@item list
+@samp{-t} in @code{tar}.
-@item dereference-args
-@samp{-D} in @code{du}.
+@item literal
+@samp{-N} in @code{ls}.
-@item diacritics
-@samp{-d} in @code{recode}.
+@item load-average
+@samp{-l} in Make.
-@item dictionary-order
-@samp{-d} in @code{look}.
+@item login
+Used in @code{su}.
-@item diff
-@samp{-d} in @code{tar}.
+@item machine
+No listing of which programs already use this;
+someone should check to
+see if any actually do and tell @code{gnu@@prep.ai.mit.edu}.
-@item digits
-@samp{-n} in @code{csplit}.
+@item macro-name
+@samp{-M} in @code{ptx}.
-@item directory
-Specify the directory to use, in various programs. In @code{ls}, it
-means to show directories themselves rather than their contents. In
-@code{rm} and @code{ln}, it means to not treat links to directories
-specially.
+@item mail
+@samp{-m} in @code{hello} and @code{uname}.
-@item discard-all
-@samp{-x} in @code{strip}.
+@item make-directories
+@samp{-d} in @code{cpio}.
-@item discard-locals
-@samp{-X} in @code{strip}.
+@item makefile
+@samp{-f} in Make.
-@item dry-run
-@samp{-n} in Make.
+@item mapped
+Used in GDB.
-@item ed
-@samp{-e} in @code{diff}.
+@item max-args
+@samp{-n} in @code{xargs}.
-@item elide-empty-files
-@samp{-z} in @code{csplit}.
+@item max-chars
+@samp{-n} in @code{xargs}.
+
+@item max-lines
+@samp{-l} in @code{xargs}.
-@item end-delete
-@samp{-x} in @code{wdiff}.
+@item max-load
+@samp{-l} in Make.
-@item end-insert
-@samp{-z} in @code{wdiff}.
+@item max-procs
+@samp{-P} in @code{xargs}.
-@item entire-new-file
-@samp{-N} in @code{diff}.
+@item mesg
+@samp{-T} in @code{who}.
-@item environment-overrides
-@samp{-e} in Make.
+@item message
+@samp{-T} in @code{who}.
-@item eof
-@samp{-e} in @code{xargs}.
+@item minimal
+@samp{-d} in @code{diff}.
-@item epoch
-Used in GDB.
+@item mixed-uuencode
+@samp{-M} in @code{shar}.
-@item error-limit
-Used in Makeinfo.
+@item mode
+@samp{-m} in @code{install}, @code{mkdir}, and @code{mkfifo}.
-@item error-output
-@samp{-o} in @code{m4}.
+@item modification-time
+@samp{-m} in @code{tar}.
-@item escape
-@samp{-b} in @code{ls}.
+@item multi-volume
+@samp{-M} in @code{tar}.
-@item exclude-from
-@samp{-X} in @code{tar}.
+@item name-prefix
+@samp{-a} in Bison.
-@item exec
-Used in GDB.
+@item nesting-limit
+@samp{-L} in @code{m4}.
-@item exit
-@samp{-x} in @code{xargs}.
+@item net-headers
+@samp{-a} in @code{shar}.
-@item exit-0
-@samp{-e} in @code{unshar}.
+@item new-file
+@samp{-W} in Make.
-@item expand-tabs
-@samp{-t} in @code{diff}.
+@item no-builtin-rules
+@samp{-r} in Make.
-@item expression
-@samp{-e} in @code{sed}.
+@item no-character-count
+@samp{-w} in @code{shar}.
-@item extern-only
-@samp{-g} in @code{nm}.
+@item no-check-existing
+@samp{-x} in @code{shar}.
-@item extract
-@samp{-i} in @code{cpio};
-@samp{-x} in @code{tar}.
+@item no-common
+@samp{-3} in @code{wdiff}.
-@item faces
-@samp{-f} in @code{finger}.
+@item no-create
+@samp{-c} in @code{touch}.
-@item fast
-@samp{-f} in @code{su}.
+@item no-defines
+@samp{-D} in @code{etags}.
-@item fatal-warnings
-@samp{-E} in @code{m4}.
+@item no-deleted
+@samp{-1} in @code{wdiff}.
-@item field-separator
-p@samp{-F} in Gawk.
+@item no-dereference
+@samp{-d} in @code{cp}.
-@item file
-@samp{-f} in Gawk, @code{info}, Make, @code{mt}, and @code{tar};
-@samp{-n} in @code{sed};
-@samp{-r} in @code{touch}.
+@item no-inserted
+@samp{-2} in @code{wdiff}.
-@item file-prefix
-@samp{-b} in Bison.
+@item no-keep-going
+@samp{-S} in Make.
-@item file-type
-@samp{-F} in @code{ls}.
+@item no-lines
+@samp{-l} in Bison.
-@item files-from
-@samp{-T} in @code{tar}.
+@item no-piping
+@samp{-P} in @code{shar}.
-@item fill-column
-Used in Makeinfo.
+@item no-prof
+@samp{-e} in @code{gprof}.
-@item flag-truncation
-@samp{-F} in @code{ptx}.
+@item no-regex
+@samp{-R} in @code{etags}.
-@item fixed-output-files
-@samp{-y} in Bison.
+@item no-sort
+@samp{-p} in @code{nm}.
-@item follow
-@samp{-f} in @code{tail}.
+@item no-split
+Used in @code{makeinfo}.
-@item footnote-style
-Used in Makeinfo.
+@item no-static
+@samp{-a} in @code{gprof}.
-@item force
-@samp{-f} in @code{cp}, @code{ln}, @code{mv}, and @code{rm}.
+@item no-time
+@samp{-E} in @code{gprof}.
-@item force-prefix
-@samp{-F} in @code{shar}.
+@item no-timestamp
+@samp{-m} in @code{shar}.
-@item format
-Used in @code{ls}, @code{time}, and @code{ptx}.
+@item no-validate
+Used in @code{makeinfo}.
-@item freeze-state
-@samp{-F} in @code{m4}.
+@item no-warn
+Used in various programs to inhibit warnings.
-@item fullname
-Used in GDB.
+@item node
+@samp{-n} in @code{info}.
-@item gap-size
-@samp{-g} in @code{ptx}.
+@item nodename
+@samp{-n} in @code{uname}.
-@item get
-@samp{-x} in @code{tar}.
+@item nonmatching
+@samp{-f} in @code{cpio}.
-@item graphic
-@samp{-i} in @code{ul}.
+@item nstuff
+@samp{-n} in @code{objdump}.
-@item graphics
-@samp{-g} in @code{recode}.
+@item null
+@samp{-0} in @code{xargs}.
-@item group
-@samp{-g} in @code{install}.
+@item number
+@samp{-n} in @code{cat}.
-@item gzip
-@samp{-z} in @code{tar} and @code{shar}.
+@item number-nonblank
+@samp{-b} in @code{cat}.
-@item hashsize
-@samp{-H} in @code{m4}.
+@item numeric-sort
+@samp{-n} in @code{nm}.
-@item header
-@samp{-h} in @code{objdump} and @code{recode}
+@item numeric-uid-gid
+@samp{-n} in @code{cpio} and @code{ls}.
-@item heading
-@samp{-H} in @code{who}.
+@item nx
+Used in GDB.
-@item help
-Used to ask for brief usage information.
+@item old-archive
+@samp{-o} in @code{tar}.
-@item here-delimiter
-@samp{-d} in @code{shar}.
+@item old-file
+@samp{-o} in Make.
-@item hide-control-chars
-@samp{-q} in @code{ls}.
+@item one-file-system
+@samp{-l} in @code{tar}, @code{cp}, and @code{du}.
-@item idle
-@samp{-u} in @code{who}.
+@item only-file
+@samp{-o} in @code{ptx}.
-@item ifdef
-@samp{-D} in @code{diff}.
+@item only-prof
+@samp{-f} in @code{gprof}.
-@item ignore
-@samp{-I} in @code{ls};
-@samp{-x} in @code{recode}.
+@item only-time
+@samp{-F} in @code{gprof}.
-@item ignore-all-space
-@samp{-w} in @code{diff}.
+@item output
+In various programs, specify the output file name.
-@item ignore-backups
-@samp{-B} in @code{ls}.
+@item output-prefix
+@samp{-o} in @code{shar}.
-@item ignore-blank-lines
-@samp{-B} in @code{diff}.
+@item override
+@samp{-o} in @code{rm}.
-@item ignore-case
-@samp{-f} in @code{look} and @code{ptx};
-@samp{-i} in @code{diff} and @code{wdiff}.
+@item overwrite
+@samp{-c} in @code{unshar}.
-@item ignore-errors
-@samp{-i} in Make.
+@item owner
+@samp{-o} in @code{install}.
-@item ignore-file
-@samp{-i} in @code{ptx}.
+@item paginate
+@samp{-l} in @code{diff}.
-@item ignore-indentation
-@samp{-I} in @code{etags}.
+@item paragraph-indent
+Used in @code{makeinfo}.
-@item ignore-init-file
-@samp{-f} in Oleo.
+@item parents
+@samp{-p} in @code{mkdir} and @code{rmdir}.
-@item ignore-interrupts
-@samp{-i} in @code{tee}.
+@item pass-all
+@samp{-p} in @code{ul}.
-@item ignore-matching-lines
-@samp{-I} in @code{diff}.
+@item pass-through
+@samp{-p} in @code{cpio}.
-@item ignore-space-change
-@samp{-b} in @code{diff}.
+@item port
+@samp{-P} in @code{finger}.
-@item ignore-zeros
-@samp{-i} in @code{tar}.
+@item portability
+@samp{-c} in @code{cpio} and @code{tar}.
-@item include
-@samp{-i} in @code{etags};
-@samp{-I} in @code{m4}.
+@item posix
+Used in @code{gawk}.
-@item include-dir
-@samp{-I} in Make.
+@item prefix-builtins
+@samp{-P} in @code{m4}.
+
+@item prefix
+@samp{-f} in @code{csplit}.
-@item incremental
-@samp{-G} in @code{tar}.
+@item preserve
+Used in @code{tar} and @code{cp}.
-@item info
-@samp{-i}, @samp{-l}, and @samp{-m} in Finger.
+@item preserve-environment
+@samp{-p} in @code{su}.
-@item initial
-@samp{-i} in @code{expand}.
+@item preserve-modification-time
+@samp{-m} in @code{cpio}.
-@item initial-tab
-@samp{-T} in @code{diff}.
+@item preserve-order
+@samp{-s} in @code{tar}.
-@item inode
-@samp{-i} in @code{ls}.
+@item preserve-permissions
+@samp{-p} in @code{tar}.
-@item interactive
-@samp{-i} in @code{cp}, @code{ln}, @code{mv}, @code{rm};
-@samp{-e} in @code{m4};
-@samp{-p} in @code{xargs};
-@samp{-w} in @code{tar}.
+@item print
+@samp{-l} in @code{diff}.
-@item intermix-type
-@samp{-p} in @code{shar}.
+@item print-chars
+@samp{-L} in @code{cmp}.
-@item jobs
-@samp{-j} in Make.
+@item print-data-base
+@samp{-p} in Make.
-@item just-print
-@samp{-n} in Make.
+@item print-directory
+@samp{-w} in Make.
-@item keep-going
-@samp{-k} in Make.
+@item print-file-name
+@samp{-o} in @code{nm}.
-@item keep-files
-@samp{-k} in @code{csplit}.
+@item print-symdefs
+@samp{-s} in @code{nm}.
-@item kilobytes
-@samp{-k} in @code{du} and @code{ls}.
+@item printer
+@samp{-p} in @code{wdiff}.
-@item language
-@samp{-l} in @code{etags}.
+@item prompt
+@samp{-p} in @code{ed}.
-@item less-mode
-@samp{-l} in @code{wdiff}.
+@item query-user
+@samp{-X} in @code{shar}.
-@item level-for-gzip
-@samp{-g} in @code{shar}.
+@item question
+@samp{-q} in Make.
-@item line-bytes
-@samp{-C} in @code{split}.
+@item quiet
+Used in many programs to inhibit the usual output. @strong{Note:} every
+program accepting @samp{--quiet} should accept @samp{--silent} as a
+synonym.
-@item lines
-Used in @code{split}, @code{head}, and @code{tail}.
+@item quiet-unshar
+@samp{-Q} in @code{shar}
-@item link
-@samp{-l} in @code{cpio}.
+@item quote-name
+@samp{-Q} in @code{ls}.
-@item lint
-Used in gawk (no corresponding single-letter option).
+@item rcs
+@samp{-n} in @code{diff}.
-@item list
-@samp{-t} in @code{cpio};
-@samp{-l} in @code{recode}.
+@item re-interval
+Used in @code{gawk}.
-@item list
-@samp{-t} in @code{tar}.
+@item read-full-blocks
+@samp{-B} in @code{tar}.
-@item literal
-@samp{-N} in @code{ls}.
+@item readnow
+Used in GDB.
-@item load-average
-@samp{-l} in Make.
+@item recon
+@samp{-n} in Make.
-@item login
-Used in @code{su}.
+@item record-number
+@samp{-R} in @code{tar}.
-@item machine
-No listing of which programs already use this;
-someone should check to
-see if any actually do and tell @code{gnu@@prep.ai.mit.edu}.
+@item recursive
+Used in @code{chgrp}, @code{chown}, @code{cp}, @code{ls}, @code{diff},
+and @code{rm}.
-@item macro-name
-@samp{-M} in @code{ptx}.
+@item reference-limit
+Used in @code{makeinfo}.
-@item mail
-@samp{-m} in @code{hello} and @code{uname}.
+@item references
+@samp{-r} in @code{ptx}.
-@item make-directories
-@samp{-d} in @code{cpio}.
+@item regex
+@samp{-r} in @code{tac} and @code{etags}.
-@item makefile
-@samp{-f} in Make.
+@item release
+@samp{-r} in @code{uname}.
-@item mapped
-Used in GDB.
+@item reload-state
+@samp{-R} in @code{m4}.
-@item max-args
-@samp{-n} in @code{xargs}.
+@item relocation
+@samp{-r} in @code{objdump}.
-@item max-chars
-@samp{-n} in @code{xargs}.
+@item rename
+@samp{-r} in @code{cpio}.
-@item max-lines
-@samp{-l} in @code{xargs}.
+@item replace
+@samp{-i} in @code{xargs}.
-@item max-load
-@samp{-l} in Make.
+@item report-identical-files
+@samp{-s} in @code{diff}.
-@item max-procs
-@samp{-P} in @code{xargs}.
+@item reset-access-time
+@samp{-a} in @code{cpio}.
-@item mesg
-@samp{-T} in @code{who}.
+@item reverse
+@samp{-r} in @code{ls} and @code{nm}.
-@item message
-@samp{-T} in @code{who}.
+@item reversed-ed
+@samp{-f} in @code{diff}.
-@item minimal
-@samp{-d} in @code{diff}.
+@item right-side-defs
+@samp{-R} in @code{ptx}.
-@item mixed-uuencode
-@samp{-M} in @code{shar}.
+@item same-order
+@samp{-s} in @code{tar}.
-@item mode
-@samp{-m} in @code{install}, @code{mkdir}, and @code{mkfifo}.
+@item same-permissions
+@samp{-p} in @code{tar}.
-@item modification-time
-@samp{-m} in @code{tar}.
+@item save
+@samp{-g} in @code{stty}.
-@item multi-volume
-@samp{-M} in @code{tar}.
+@item se
+Used in GDB.
-@item name-prefix
-@samp{-a} in Bison.
+@item sentence-regexp
+@samp{-S} in @code{ptx}.
-@item nesting-limit
-@samp{-L} in @code{m4}.
+@item separate-dirs
+@samp{-S} in @code{du}.
-@item net-headers
-@samp{-a} in @code{shar}.
+@item separator
+@samp{-s} in @code{tac}.
-@item new-file
-@samp{-W} in Make.
+@item sequence
+Used by @code{recode} to chose files or pipes for sequencing passes.
-@item no-builtin-rules
-@samp{-r} in Make.
+@item shell
+@samp{-s} in @code{su}.
-@item no-character-count
-@samp{-w} in @code{shar}.
+@item show-all
+@samp{-A} in @code{cat}.
-@item no-check-existing
-@samp{-x} in @code{shar}.
+@item show-c-function
+@samp{-p} in @code{diff}.
-@item no-common
-@samp{-3} in @code{wdiff}.
+@item show-ends
+@samp{-E} in @code{cat}.
-@item no-create
-@samp{-c} in @code{touch}.
+@item show-function-line
+@samp{-F} in @code{diff}.
-@item no-defines
-@samp{-D} in @code{etags}.
+@item show-tabs
+@samp{-T} in @code{cat}.
-@item no-deleted
-@samp{-1} in @code{wdiff}.
+@item silent
+Used in many programs to inhibit the usual output.
+@strong{Note:} every program accepting
+@samp{--silent} should accept @samp{--quiet} as a synonym.
-@item no-dereference
-@samp{-d} in @code{cp}.
+@item size
+@samp{-s} in @code{ls}.
-@item no-inserted
-@samp{-2} in @code{wdiff}.
+@item sort
+Used in @code{ls}.
-@item no-keep-going
-@samp{-S} in Make.
+@item source
+@samp{-W source} in @code{gawk}.
-@item no-lines
-@samp{-l} in Bison.
+@item sparse
+@samp{-S} in @code{tar}.
-@item no-piping
-@samp{-P} in @code{shar}.
+@item speed-large-files
+@samp{-H} in @code{diff}.
-@item no-prof
-@samp{-e} in @code{gprof}.
+@item split-at
+@samp{-E} in @code{unshar}.
-@item no-regex
-@samp{-R} in @code{etags}.
+@item split-size-limit
+@samp{-L} in @code{shar}.
-@item no-sort
-@samp{-p} in @code{nm}.
+@item squeeze-blank
+@samp{-s} in @code{cat}.
-@item no-split
-Used in Makeinfo.
+@item start-delete
+@samp{-w} in @code{wdiff}.
+
+@item start-insert
+@samp{-y} in @code{wdiff}.
-@item no-static
-@samp{-a} in @code{gprof}.
+@item starting-file
+Used in @code{tar} and @code{diff} to specify which file within
+a directory to start processing with.
-@item no-time
-@samp{-E} in @code{gprof}.
+@item statistics
+@samp{-s} in @code{wdiff}.
-@item no-timestamp
-@samp{-m} in @code{shar}.
+@item stdin-file-list
+@samp{-S} in @code{shar}.
-@item no-validate
-Used in Makeinfo.
+@item stop
+@samp{-S} in Make.
-@item no-warn
-Used in various programs to inhibit warnings.
+@item strict
+@samp{-s} in @code{recode}.
-@item node
-@samp{-n} in @code{info}.
+@item strip
+@samp{-s} in @code{install}.
-@item nodename
-@samp{-n} in @code{uname}.
+@item strip-all
+@samp{-s} in @code{strip}.
-@item nonmatching
-@samp{-f} in @code{cpio}.
+@item strip-debug
+@samp{-S} in @code{strip}.
-@item nstuff
-@samp{-n} in @code{objdump}.
+@item submitter
+@samp{-s} in @code{shar}.
-@item null
-@samp{-0} in @code{xargs}.
+@item suffix
+@samp{-S} in @code{cp}, @code{ln}, @code{mv}.
-@item number
-@samp{-n} in @code{cat}.
+@item suffix-format
+@samp{-b} in @code{csplit}.
-@item number-nonblank
-@samp{-b} in @code{cat}.
+@item sum
+@samp{-s} in @code{gprof}.
-@item numeric-sort
-@samp{-n} in @code{nm}.
+@item summarize
+@samp{-s} in @code{du}.
-@item numeric-uid-gid
-@samp{-n} in @code{cpio} and @code{ls}.
+@item symbolic
+@samp{-s} in @code{ln}.
-@item nx
-Used in GDB.
+@item symbols
+Used in GDB and @code{objdump}.
-@item old-archive
-@samp{-o} in @code{tar}.
+@item synclines
+@samp{-s} in @code{m4}.
-@item old-file
-@samp{-o} in Make.
+@item sysname
+@samp{-s} in @code{uname}.
-@item one-file-system
-@samp{-l} in @code{tar}, @code{cp}, and @code{du}.
+@item tabs
+@samp{-t} in @code{expand} and @code{unexpand}.
-@item only-file
-@samp{-o} in @code{ptx}.
+@item tabsize
+@samp{-T} in @code{ls}.
-@item only-prof
-@samp{-f} in @code{gprof}.
+@item terminal
+@samp{-T} in @code{tput} and @code{ul}.
+@samp{-t} in @code{wdiff}.
-@item only-time
-@samp{-F} in @code{gprof}.
+@item text
+@samp{-a} in @code{diff}.
-@item output
-In various programs, specify the output file name.
+@item text-files
+@samp{-T} in @code{shar}.
-@item output-prefix
-@samp{-o} in @code{shar}.
+@item time
+Used in @code{ls} and @code{touch}.
-@item override
-@samp{-o} in @code{rm}.
+@item to-stdout
+@samp{-O} in @code{tar}.
-@item overwrite
-@samp{-c} in @code{unshar}.
+@item total
+@samp{-c} in @code{du}.
-@item owner
-@samp{-o} in @code{install}.
+@item touch
+@samp{-t} in Make, @code{ranlib}, and @code{recode}.
-@item paginate
-@samp{-l} in @code{diff}.
+@item trace
+@samp{-t} in @code{m4}.
-@item paragraph-indent
-Used in Makeinfo.
+@item traditional
+@samp{-t} in @code{hello};
+@samp{-W traditional} in @code{gawk};
+@samp{-G} in @code{ed}, @code{m4}, and @code{ptx}.
-@item parents
-@samp{-p} in @code{mkdir} and @code{rmdir}.
+@item tty
+Used in GDB.
-@item pass-all
-@samp{-p} in @code{ul}.
+@item typedefs
+@samp{-t} in @code{ctags}.
-@item pass-through
-@samp{-p} in @code{cpio}.
+@item typedefs-and-c++
+@samp{-T} in @code{ctags}.
-@item port
-@samp{-P} in @code{finger}.
+@item typeset-mode
+@samp{-t} in @code{ptx}.
-@item portability
-@samp{-c} in @code{cpio} and @code{tar}.
+@item uncompress
+@samp{-z} in @code{tar}.
-@item posix
-Used in gawk (no corresponding single-letter option).
+@item unconditional
+@samp{-u} in @code{cpio}.
-@item prefix-builtins
-@samp{-P} in @code{m4}.
+@item undefine
+@samp{-U} in @code{m4}.
-@item prefix
-@samp{-f} in @code{csplit}.
+@item undefined-only
+@samp{-u} in @code{nm}.
-@item preserve
-Used in @code{tar} and @code{cp}.
+@item update
+@samp{-u} in @code{cp}, @code{ctags}, @code{mv}, @code{tar}.
-@item preserve-environment
-@samp{-p} in @code{su}.
+@item usage
+Used in @code{gawk}; same as @samp{--help}.
-@item preserve-modification-time
-@samp{-m} in @code{cpio}.
+@item uuencode
+@samp{-B} in @code{shar}.
-@item preserve-order
-@samp{-s} in @code{tar}.
+@item vanilla-operation
+@samp{-V} in @code{shar}.
-@item preserve-permissions
-@samp{-p} in @code{tar}.
+@item verbose
+Print more information about progress. Many programs support this.
-@item print
-@samp{-l} in @code{diff}.
+@item verify
+@samp{-W} in @code{tar}.
-@item print-chars
-@samp{-L} in @code{cmp}.
+@item version
+Print the version number.
-@item print-data-base
-@samp{-p} in Make.
+@item version-control
+@samp{-V} in @code{cp}, @code{ln}, @code{mv}.
-@item print-directory
-@samp{-w} in Make.
+@item vgrind
+@samp{-v} in @code{ctags}.
-@item print-file-name
-@samp{-o} in @code{nm}.
+@item volume
+@samp{-V} in @code{tar}.
-@item print-symdefs
-@samp{-s} in @code{nm}.
+@item what-if
+@samp{-W} in Make.
-@item printer
-@samp{-p} in @code{wdiff}.
+@item whole-size-limit
+@samp{-l} in @code{shar}.
-@item prompt
-@samp{-p} in @code{ed}.
+@item width
+@samp{-w} in @code{ls} and @code{ptx}.
-@item query-user
-@samp{-X} in @code{shar}.
+@item word-regexp
+@samp{-W} in @code{ptx}.
-@item question
-@samp{-q} in Make.
+@item writable
+@samp{-T} in @code{who}.
-@item quiet
-Used in many programs to inhibit the usual output. @strong{Note:} every
-program accepting @samp{--quiet} should accept @samp{--silent} as a
-synonym.
+@item zeros
+@samp{-z} in @code{gprof}.
-@item quiet-unshar
-@samp{-Q} in @code{shar}
+@end table
-@item quote-name
-@samp{-Q} in @code{ls}.
+@node Writing C
+@chapter Making The Best Use of C
-@item rcs
-@samp{-n} in @code{diff}.
+This @value{CHAPTER} provides advice on how best to use the C language
+when writing GNU software.
-@item read-full-blocks
-@samp{-B} in @code{tar}.
+@menu
+* Formatting:: Formatting Your Source Code
+* Comments:: Commenting Your Work
+* Syntactic Conventions:: Clean Use of C Constructs
+* Names:: Naming Variables and Functions
+* System Functions:: Portability and ``standard'' library functions
+@end menu
-@item readnow
-Used in GDB.
+@node Formatting
+@section Formatting Your Source Code
-@item recon
-@samp{-n} in Make.
+It is important to put the open-brace that starts the body of a C
+function in column zero, and avoid putting any other open-brace or
+open-parenthesis or open-bracket in column zero. Several tools look
+for open-braces in column zero to find the beginnings of C functions.
+These tools will not work on code not formatted that way.
-@item record-number
-@samp{-R} in @code{tar}.
+It is also important for function definitions to start the name of the
+function in column zero. This helps people to search for function
+definitions, and may also help certain tools recognize them. Thus,
+the proper format is this:
-@item recursive
-Used in @code{chgrp}, @code{chown}, @code{cp}, @code{ls}, @code{diff},
-and @code{rm}.
+@example
+static char *
+concat (s1, s2) /* Name starts in column zero here */
+ char *s1, *s2;
+@{ /* Open brace in column zero here */
+ @dots{}
+@}
+@end example
-@item reference-limit
-Used in Makeinfo.
+@noindent
+or, if you want to use @sc{ANSI} C, format the definition like this:
-@item references
-@samp{-r} in @code{ptx}.
+@example
+static char *
+concat (char *s1, char *s2)
+@{
+ @dots{}
+@}
+@end example
-@item regex
-@samp{-r} in @code{tac} and @code{etags}.
+In @sc{ANSI} C, if the arguments don't fit nicely on one line,
+split it like this:
-@item release
-@samp{-r} in @code{uname}.
+@example
+int
+lots_of_args (int an_integer, long a_long, short a_short,
+ double a_double, float a_float)
+@dots{}
+@end example
-@item reload-state
-@samp{-R} in @code{m4}.
+For the body of the function, we prefer code formatted like this:
-@item relocation
-@samp{-r} in @code{objdump}.
+@example
+if (x < foo (y, z))
+ haha = bar[4] + 5;
+else
+ @{
+ while (z)
+ @{
+ haha += foo (z, z);
+ z--;
+ @}
+ return ++x + bar ();
+ @}
+@end example
-@item rename
-@samp{-r} in @code{cpio}.
+We find it easier to read a program when it has spaces before the
+open-parentheses and after the commas. Especially after the commas.
-@item replace
-@samp{-i} in @code{xargs}.
+When you split an expression into multiple lines, split it
+before an operator, not after one. Here is the right way:
-@item report-identical-files
-@samp{-s} in @code{diff}.
+@example
+if (foo_this_is_long && bar > win (x, y, z)
+ && remaining_condition)
+@end example
-@item reset-access-time
-@samp{-a} in @code{cpio}.
+Try to avoid having two operators of different precedence at the same
+level of indentation. For example, don't write this:
-@item reverse
-@samp{-r} in @code{ls} and @code{nm}.
+@example
+mode = (inmode[j] == VOIDmode
+ || GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j])
+ ? outmode[j] : inmode[j]);
+@end example
-@item reversed-ed
-@samp{-f} in @code{diff}.
+Instead, use extra parentheses so that the indentation shows the nesting:
-@item right-side-defs
-@samp{-R} in @code{ptx}.
+@example
+mode = ((inmode[j] == VOIDmode
+ || (GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j])))
+ ? outmode[j] : inmode[j]);
+@end example
-@item same-order
-@samp{-s} in @code{tar}.
+Insert extra parentheses so that Emacs will indent the code properly.
+For example, the following indentation looks nice if you do it by hand,
+but Emacs would mess it up:
-@item same-permissions
-@samp{-p} in @code{tar}.
+@example
+v = rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
+ + rup->ru_stime.tv_sec*1000 + rup->ru_stime.tv_usec/1000;
+@end example
-@item save
-@samp{-g} in @code{stty}.
+But adding a set of parentheses solves the problem:
-@item se
-Used in GDB.
+@example
+v = (rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
+ + rup->ru_stime.tv_sec*1000 + rup->ru_stime.tv_usec/1000);
+@end example
-@item sentence-regexp
-@samp{-S} in @code{ptx}.
+Format do-while statements like this:
-@item separate-dirs
-@samp{-S} in @code{du}.
+@example
+do
+ @{
+ a = foo (a);
+ @}
+while (a > 0);
+@end example
-@item separator
-@samp{-s} in @code{tac}.
+Please use formfeed characters (control-L) to divide the program into
+pages at logical places (but not within a function). It does not matter
+just how long the pages are, since they do not have to fit on a printed
+page. The formfeeds should appear alone on lines by themselves.
-@item sequence
-Used by @code{recode} to chose files or pipes for sequencing passes.
-@item shell
-@samp{-s} in @code{su}.
+@node Comments
+@section Commenting Your Work
-@item show-all
-@samp{-A} in @code{cat}.
+Every program should start with a comment saying briefly what it is for.
+Example: @samp{fmt - filter for simple filling of text}.
-@item show-c-function
-@samp{-p} in @code{diff}.
+Please put a comment on each function saying what the function does,
+what sorts of arguments it gets, and what the possible values of
+arguments mean and are used for. It is not necessary to duplicate in
+words the meaning of the C argument declarations, if a C type is being
+used in its customary fashion. If there is anything nonstandard about
+its use (such as an argument of type @code{char *} which is really the
+address of the second character of a string, not the first), or any
+possible values that would not work the way one would expect (such as,
+that strings containing newlines are not guaranteed to work), be sure
+to say so.
-@item show-ends
-@samp{-E} in @code{cat}.
+Also explain the significance of the return value, if there is one.
-@item show-function-line
-@samp{-F} in @code{diff}.
+Please put two spaces after the end of a sentence in your comments, so
+that the Emacs sentence commands will work. Also, please write
+complete sentences and capitalize the first word. If a lower-case
+identifier comes at the beginning of a sentence, don't capitalize it!
+Changing the spelling makes it a different identifier. If you don't
+like starting a sentence with a lower case letter, write the sentence
+differently (e.g., ``The identifier lower-case is @dots{}'').
-@item show-tabs
-@samp{-T} in @code{cat}.
+The comment on a function is much clearer if you use the argument
+names to speak about the argument values. The variable name itself
+should be lower case, but write it in upper case when you are speaking
+about the value rather than the variable itself. Thus, ``the inode
+number NODE_NUM'' rather than ``an inode''.
-@item silent
-Used in many programs to inhibit the usual output.
-@strong{Note:} every program accepting
-@samp{--silent} should accept @samp{--quiet} as a synonym.
+There is usually no purpose in restating the name of the function in
+the comment before it, because the reader can see that for himself.
+There might be an exception when the comment is so long that the function
+itself would be off the bottom of the screen.
-@item size
-@samp{-s} in @code{ls}.
+There should be a comment on each static variable as well, like this:
-@item sort
-Used in @code{ls}.
+@example
+/* Nonzero means truncate lines in the display;
+ zero means continue them. */
+int truncate_lines;
+@end example
-@item source
-Used in gawk (no corresponding single-letter option).
+Every @samp{#endif} should have a comment, except in the case of short
+conditionals (just a few lines) that are not nested. The comment should
+state the condition of the conditional that is ending, @emph{including
+its sense}. @samp{#else} should have a comment describing the condition
+@emph{and sense} of the code that follows. For example:
-@item sparse
-@samp{-S} in @code{tar}.
+@example
+@group
+#ifdef foo
+ @dots{}
+#else /* not foo */
+ @dots{}
+#endif /* not foo */
+@end group
+@end example
-@item speed-large-files
-@samp{-H} in @code{diff}.
+@noindent
+but, by contrast, write the comments this way for a @samp{#ifndef}:
-@item split-at
-@samp{-E} in @code{unshar}.
+@example
+@group
+#ifndef foo
+ @dots{}
+#else /* foo */
+ @dots{}
+#endif /* foo */
+@end group
+@end example
-@item split-size-limit
-@samp{-L} in @code{shar}.
-@item squeeze-blank
-@samp{-s} in @code{cat}.
+@node Syntactic Conventions
+@section Clean Use of C Constructs
-@item start-delete
-@samp{-w} in @code{wdiff}.
+Please explicitly declare all arguments to functions.
+Don't omit them just because they are @code{int}s.
-@item start-insert
-@samp{-y} in @code{wdiff}.
+Declarations of external functions and functions to appear later in the
+source file should all go in one place near the beginning of the file
+(somewhere before the first function definition in the file), or else
+should go in a header file. Don't put @code{extern} declarations inside
+functions.
-@item starting-file
-Used in @code{tar} and @code{diff} to specify which file within
-a directory to start processing with.
+It used to be common practice to use the same local variables (with
+names like @code{tem}) over and over for different values within one
+function. Instead of doing this, it is better declare a separate local
+variable for each distinct purpose, and give it a name which is
+meaningful. This not only makes programs easier to understand, it also
+facilitates optimization by good compilers. You can also move the
+declaration of each local variable into the smallest scope that includes
+all its uses. This makes the program even cleaner.
-@item statistics
-@samp{-s} in @code{wdiff}.
+Don't use local variables or parameters that shadow global identifiers.
-@item stdin-file-list
-@samp{-S} in @code{shar}.
+Don't declare multiple variables in one declaration that spans lines.
+Start a new declaration on each line, instead. For example, instead
+of this:
-@item stop
-@samp{-S} in Make.
+@example
+@group
+int foo,
+ bar;
+@end group
+@end example
-@item strict
-@samp{-s} in @code{recode}.
+@noindent
+write either this:
-@item strip
-@samp{-s} in @code{install}.
+@example
+int foo, bar;
+@end example
-@item strip-all
-@samp{-s} in @code{strip}.
+@noindent
+or this:
-@item strip-debug
-@samp{-S} in @code{strip}.
+@example
+int foo;
+int bar;
+@end example
-@item submitter
-@samp{-s} in @code{shar}.
+@noindent
+(If they are global variables, each should have a comment preceding it
+anyway.)
-@item suffix
-@samp{-S} in @code{cp}, @code{ln}, @code{mv}.
+When you have an @code{if}-@code{else} statement nested in another
+@code{if} statement, always put braces around the @code{if}-@code{else}.
+Thus, never write like this:
-@item suffix-format
-@samp{-b} in @code{csplit}.
+@example
+if (foo)
+ if (bar)
+ win ();
+ else
+ lose ();
+@end example
-@item sum
-@samp{-s} in @code{gprof}.
+@noindent
+always like this:
-@item summarize
-@samp{-s} in @code{du}.
+@example
+if (foo)
+ @{
+ if (bar)
+ win ();
+ else
+ lose ();
+ @}
+@end example
-@item symbolic
-@samp{-s} in @code{ln}.
+If you have an @code{if} statement nested inside of an @code{else}
+statement, either write @code{else if} on one line, like this,
-@item symbols
-Used in GDB and @code{objdump}.
+@example
+if (foo)
+ @dots{}
+else if (bar)
+ @dots{}
+@end example
-@item synclines
-@samp{-s} in @code{m4}.
+@noindent
+with its @code{then}-part indented like the preceding @code{then}-part,
+or write the nested @code{if} within braces like this:
-@item sysname
-@samp{-s} in @code{uname}.
+@example
+if (foo)
+ @dots{}
+else
+ @{
+ if (bar)
+ @dots{}
+ @}
+@end example
-@item tabs
-@samp{-t} in @code{expand} and @code{unexpand}.
+Don't declare both a structure tag and variables or typedefs in the
+same declaration. Instead, declare the structure tag separately
+and then use it to declare the variables or typedefs.
-@item tabsize
-@samp{-T} in @code{ls}.
+Try to avoid assignments inside @code{if}-conditions. For example,
+don't write this:
-@item terminal
-@samp{-T} in @code{tput} and @code{ul}.
-@samp{-t} in @code{wdiff}.
+@example
+if ((foo = (char *) malloc (sizeof *foo)) == 0)
+ fatal ("virtual memory exhausted");
+@end example
-@item text
-@samp{-a} in @code{diff}.
+@noindent
+instead, write this:
-@item text-files
-@samp{-T} in @code{shar}.
+@example
+foo = (char *) malloc (sizeof *foo);
+if (foo == 0)
+ fatal ("virtual memory exhausted");
+@end example
-@item time
-Used in @code{ls} and @code{touch}.
+Don't make the program ugly to placate @code{lint}. Please don't insert any
+casts to @code{void}. Zero without a cast is perfectly fine as a null
+pointer constant.
-@item to-stdout
-@samp{-O} in @code{tar}.
+@node Names
+@section Naming Variables and Functions
-@item total
-@samp{-c} in @code{du}.
+Please use underscores to separate words in a name, so that the Emacs
+word commands can be useful within them. Stick to lower case; reserve
+upper case for macros and @code{enum} constants, and for name-prefixes
+that follow a uniform convention.
-@item touch
-@samp{-t} in Make, @code{ranlib}, and @code{recode}.
+For example, you should use names like @code{ignore_space_change_flag};
+don't use names like @code{iCantReadThis}.
-@item trace
-@samp{-t} in @code{m4}.
+Variables that indicate whether command-line options have been
+specified should be named after the meaning of the option, not after
+the option-letter. A comment should state both the exact meaning of
+the option and its letter. For example,
-@item traditional
-@samp{-t} in @code{hello};
-@samp{-G} in @code{ed}, @code{m4}, and @code{ptx}.
+@example
+@group
+/* Ignore changes in horizontal whitespace (-b). */
+int ignore_space_change_flag;
+@end group
+@end example
-@item tty
-Used in GDB.
+When you want to define names with constant integer values, use
+@code{enum} rather than @samp{#define}. GDB knows about enumeration
+constants.
-@item typedefs
-@samp{-t} in @code{ctags}.
+Use file names of 14 characters or less, to avoid creating gratuitous
+problems on older System V systems. You can use the program @code{doschk} to test for
+this. @code{doschk} also tests for potential name conflicts if the
+files were loaded onto an MS-DOS file system---something you may or may
+not care about.
-@item typedefs-and-c++
-@samp{-T} in @code{ctags}.
-@item typeset-mode
-@samp{-t} in @code{ptx}.
-@item uncompress
-@samp{-z} in @code{tar}.
+@node System Functions
+@section Calling System Functions
-@item unconditional
-@samp{-u} in @code{cpio}.
+C implementations differ substantially. ANSI C reduces but does not
+eliminate the incompatibilities; meanwhile, many users wish to compile
+GNU software with pre-ANSI compilers. This chapter gives
+recommendations for how to use the more or less standard C library
+functions to avoid unnecessary loss of portability.
-@item undefine
-@samp{-U} in @code{m4}.
+@itemize @bullet
+@item
+Don't use the value of @code{sprintf}. It returns the number of
+characters written on some systems, but not on all systems.
-@item undefined-only
-@samp{-u} in @code{nm}.
+@item
+Don't declare system functions explicitly.
-@item update
-@samp{-u} in @code{cp}, @code{ctags}, @code{mv}, @code{tar}.
+Almost any declaration for a system function is wrong on some system.
+To minimize conflicts, leave it to the system header files to declare
+system functions. If the headers don't declare a function, let it
+remain undeclared.
-@item usage
-Used in gawk (no corresponding single-letter option).
+While it may seem unclean to use a function without declaring it, in
+practice this works fine for most system library functions on the
+systems where this really happens. The problem is only theoretical. By
+contrast, actual declarations have frequently caused actual conflicts.
-@item uuencode
-@samp{-B} in @code{shar}.
+@item
+If you must declare a system function, don't specify the argument types.
+Use an old-style declaration, not an ANSI prototype. The more you
+specify about the function, the more likely a conflict.
-@item vanilla-operation
-@samp{-V} in @code{shar}.
+@item
+In particular, don't unconditionally declare @code{malloc} or
+@code{realloc}.
-@item verbose
-Print more information about progress. Many programs support this.
+Most GNU programs use those functions just once, in functions
+conventionally named @code{xmalloc} and @code{xrealloc}. These
+functions call @code{malloc} and @code{realloc}, respectively, and
+check the results.
-@item verify
-@samp{-W} in @code{tar}.
+Because @code{xmalloc} and @code{xrealloc} are defined in your program,
+you can declare them in other files without any risk of type conflict.
-@item version
-Print the version number.
+On most systems, @code{int} is the same length as a pointer; thus, the
+calls to @code{malloc} and @code{realloc} work fine. For the few
+exceptional systems (mostly 64-bit machines), you can use
+@strong{conditionalized} declarations of @code{malloc} and
+@code{realloc}---or put these declarations in configuration files
+specific to those systems.
-@item version-control
-@samp{-V} in @code{cp}, @code{ln}, @code{mv}.
+@item
+The string functions require special treatment. Some Unix systems have
+a header file @file{string.h}; others have @file{strings.h}. Neither
+file name is portable. There are two things you can do: use Autoconf to
+figure out which file to include, or don't include either file.
-@item vgrind
-@samp{-v} in @code{ctags}.
+@item
+If you don't include either strings file, you can't get declarations for
+the string functions from the header file in the usual way.
-@item volume
-@samp{-V} in @code{tar}.
+That causes less of a problem than you might think. The newer ANSI
+string functions are off-limits anyway because many systems still don't
+support them. The string functions you can use are these:
-@item what-if
-@samp{-W} in Make.
+@example
+strcpy strncpy strcat strncat
+strlen strcmp strncmp
+strchr strrchr
+@end example
-@item whole-size-limit
-@samp{-l} in @code{shar}.
+The copy and concatenate functions work fine without a declaration as
+long as you don't use their values. Using their values without a
+declaration fails on systems where the width of a pointer differs from
+the width of @code{int}, and perhaps in other cases. It is trivial to
+avoid using their values, so do that.
-@item width
-@samp{-w} in @code{ls} and @code{ptx}.
+The compare functions and @code{strlen} work fine without a declaration
+on most systems, possibly all the ones that GNU software runs on.
+You may find it necessary to declare them @strong{conditionally} on a
+few systems.
-@item word-regexp
-@samp{-W} in @code{ptx}.
+The search functions must be declared to return @code{char *}. Luckily,
+there is no variation in the data type they return. But there is
+variation in their names. Some systems give these functions the names
+@code{index} and @code{rindex}; other systems use the names
+@code{strchr} and @code{strrchr}. Some systems support both pairs of
+names, but neither pair works on all systems.
-@item writable
-@samp{-T} in @code{who}.
+You should pick a single pair of names and use it throughout your
+program. (Nowadays, it is better to choose @code{strchr} and
+@code{strrchr}.) Declare both of those names as functions returning
+@code{char *}. On systems which don't support those names, define them
+as macros in terms of the other pair. For example, here is what to put
+at the beginning of your file (or in a header) if you want to use the
+names @code{strchr} and @code{strrchr} throughout:
-@item zeros
-@samp{-z} in @code{gprof}.
+@example
+#ifndef HAVE_STRCHR
+#define strchr index
+#endif
+#ifndef HAVE_STRRCHR
+#define strrchr rindex
+#endif
-@end table
-@c longopts end here (keyword for isearch)
+char *strchr ();
+char *strrchr ();
+@end example
+@end itemize
+
+Here we assume that @code{HAVE_STRCHR} and @code{HAVE_STRRCHR} are
+macros defined in systems where the corresponding functions exist.
+One way to get them properly defined is to use Autoconf.
@node Documentation
@chapter Documenting Programs
* GNU Manuals:: Writing proper manuals.
* Manual Structure Details:: Specific structure conventions.
* NEWS File:: NEWS files supplement manuals.
+* Change Logs:: Recording Changes
* Man Pages:: Man pages are secondary.
* Reading other Manuals:: How far you can go in learning
- from other manuals.
+ from other manuals.
@end menu
@node GNU Manuals
The preferred way to document part of the GNU system is to write a
manual in the Texinfo formatting language. See the Texinfo manual,
-either the hardcopy or the version in the Emacs Info subsystem (@kbd{C-h
-i}).
+either the hardcopy, or the on-line version available through
+@code{info} or the Emacs Info subsystem (@kbd{C-h i}).
The manual should document all of the program's command-line options and
all of its commands. It should give examples of their use. But don't
should give a good introduction to a beginner reading through from the
start, and should also provide all the details that hackers want.
-That is not as hard as it sounds at first. Arrange each chapter as a
+That is not as hard as it first sounds. Arrange each chapter as a
logical breakdown of its topic, but order the sections, and write their
text, so that reading the chapter straight through makes sense. Do
likewise when structuring the book into chapters, and when structuring a
@section Manual Structure Details
The title page of the manual should state the version of the program
-which the manual applies to. The Top node of the manual should also
+to which the manual applies. The Top node of the manual should also
contain this information. If the manual is changing more frequently
than or independent of the program, also state a version number for
the manual in both of these places.
into a file named @file{ONEWS} and put a note at the end referring the
user to that file.
+@node Change Logs
+@section Change Logs
+
+Keep a change log for each directory, describing the changes made to
+source files in that directory. The purpose of this is so that people
+investigating bugs in the future will know about the changes that
+might have introduced the bug. Often a new bug can be found by
+looking at what was recently changed. More importantly, change logs
+can help eliminate conceptual inconsistencies between different parts
+of a program; they can give you a history of how the conflicting
+concepts arose.
+
+Use the Emacs command @kbd{M-x add-change-log-entry} to start a new
+entry in the
+change log. An entry should have an asterisk, the name of the changed
+file, and then in parentheses the name of the changed functions,
+variables or whatever, followed by a colon. Then describe the changes
+you made to that function or variable.
+
+Separate unrelated entries with blank lines. When two entries
+represent parts of the same change, so that they work together, then
+don't put blank lines between them. Then you can omit the file name
+and the asterisk when successive entries are in the same file.
+
+Here are some examples:
+
+@example
+* register.el (insert-register): Return nil.
+(jump-to-register): Likewise.
+
+* sort.el (sort-subr): Return nil.
+
+* tex-mode.el (tex-bibtex-file, tex-file, tex-region):
+Restart the tex shell if process is gone or stopped.
+(tex-shell-running): New function.
+
+* expr.c (store_one_arg): Round size up for move_block_to_reg.
+(expand_call): Round up when emitting USE insns.
+* stmt.c (assign_parms): Round size up for move_block_from_reg.
+@end example
+
+It's important to name the changed function or variable in full. Don't
+abbreviate function or variable names, and don't combine them.
+Subsequent maintainers will often
+search for a function name to find all the change log entries that
+pertain to it; if you abbreviate the name, they won't find it when they
+search. For example, some people are tempted to abbreviate groups of
+function names by writing @samp{* register.el
+(@{insert,jump-to@}-register)}; this is not a good idea, since searching
+for @code{jump-to-register} or @code{insert-register} would not find the
+entry.
+
+There's no need to describe the full purpose of the changes or how they
+work together. It is better to put such explanations in comments in the
+code. That's why just ``New function'' is enough; there is a comment
+with the function in the source to explain what it does.
+
+However, sometimes it is useful to write one line to describe the
+overall purpose of a large batch of changes.
+
+You can think of the change log as a conceptual ``undo list'' which
+explains how earlier versions were different from the current version.
+People can see the current version; they don't need the change log
+to tell them what is in it. What they want from a change log is a
+clear explanation of how the earlier version differed.
+
+When you change the calling sequence of a function in a simple
+fashion, and you change all the callers of the function, there is no
+need to make individual entries for all the callers. Just write in
+the entry for the function being called, ``All callers changed.''
+
+When you change just comments or doc strings, it is enough to write an
+entry for the file, without mentioning the functions. Write just,
+``Doc fix.'' There's no need to keep a change log for documentation
+files. This is because documentation is not susceptible to bugs that
+are hard to fix. Documentation does not consist of parts that must
+interact in a precisely engineered fashion; to correct an error, you
+need not know the history of the erroneous passage.
+
@node Man Pages
@section Man Pages
documentation. Copying from free documentation may be ok; please check
with the FSF about the individual case.
+@node Managing Releases
+@chapter The Release Process
+
+Making a release is more than just bundling up your source files in a
+tar file and putting it up for FTP. You should set up your software so
+that it can be configured to run on a variety of systems. Your Makefile
+should conform to the GNU standards described below, and your directory
+layout should also conform to the standards discussed below. Doing so
+makes it easy to include your package into the larger framework of
+all GNU software.
+
+@menu
+* Configuration:: How Configuration Should Work
+* Makefile Conventions:: Makefile Conventions
+* Releases:: Making Releases
+@end menu
+
+@node Configuration
+@section How Configuration Should Work
+
+Each GNU distribution should come with a shell script named
+@code{configure}. This script is given arguments which describe the
+kind of machine and system you want to compile the program for.
+
+The @code{configure} script must record the configuration options so
+that they affect compilation.
+
+One way to do this is to make a link from a standard name such as
+@file{config.h} to the proper configuration file for the chosen system.
+If you use this technique, the distribution should @emph{not} contain a
+file named @file{config.h}. This is so that people won't be able to
+build the program without configuring it first.
+
+Another thing that @code{configure} can do is to edit the Makefile. If
+you do this, the distribution should @emph{not} contain a file named
+@file{Makefile}. Instead, it should include a file @file{Makefile.in} which
+contains the input used for editing. Once again, this is so that people
+won't be able to build the program without configuring it first.
+
+If @code{configure} does write the @file{Makefile}, then @file{Makefile}
+should have a target named @file{Makefile} which causes @code{configure}
+to be rerun, setting up the same configuration that was set up last
+time. The files that @code{configure} reads should be listed as
+dependencies of @file{Makefile}.
+
+All the files which are output from the @code{configure} script should
+have comments at the beginning explaining that they were generated
+automatically using @code{configure}. This is so that users won't think
+of trying to edit them by hand.
+
+The @code{configure} script should write a file named @file{config.status}
+which describes which configuration options were specified when the
+program was last configured. This file should be a shell script which,
+if run, will recreate the same configuration.
+
+The @code{configure} script should accept an option of the form
+@samp{--srcdir=@var{dirname}} to specify the directory where sources are found
+(if it is not the current directory). This makes it possible to build
+the program in a separate directory, so that the actual source directory
+is not modified.
+
+If the user does not specify @samp{--srcdir}, then @code{configure} should
+check both @file{.} and @file{..} to see if it can find the sources. If
+it finds the sources in one of these places, it should use them from
+there. Otherwise, it should report that it cannot find the sources, and
+should exit with nonzero status.
+
+Usually the easy way to support @samp{--srcdir} is by editing a
+definition of @code{VPATH} into the Makefile. Some rules may need to
+refer explicitly to the specified source directory. To make this
+possible, @code{configure} can add to the Makefile a variable named
+@code{srcdir} whose value is precisely the specified directory.
+
+The @code{configure} script should also take an argument which specifies the
+type of system to build the program for. This argument should look like
+this:
+
+@example
+@var{cpu}-@var{company}-@var{system}
+@end example
+
+For example, a Sun 3 might be @samp{m68k-sun-sunos4.1}.
+
+The @code{configure} script needs to be able to decode all plausible
+alternatives for how to describe a machine. Thus, @samp{sun3-sunos4.1}
+would be a valid alias. For many programs, @samp{vax-dec-ultrix} would
+be an alias for @samp{vax-dec-bsd}, simply because the differences
+between Ultrix and @sc{BSD} are rarely noticeable, but a few programs
+might need to distinguish them.
+@c Real 4.4BSD now runs on some Suns.
+
+There is a shell script called @file{config.sub} that you can use
+as a subroutine to validate system types and canonicalize aliases.
+
+Other options are permitted to specify in more detail the software
+or hardware present on the machine, and include or exclude optional
+parts of the package:
+
+@table @samp
+@item --enable-@var{feature}@r{[}=@var{parameter}@r{]}
+Configure the package to build and install an optional user-level
+facility called @var{feature}. This allows users to choose which
+optional features to include. Giving an optional @var{parameter} of
+@samp{no} should omit @var{feature}, if it is built by default.
+
+No @samp{--enable} option should @strong{ever} cause one feature to
+replace another. No @samp{--enable} option should ever substitute one
+useful behavior for another useful behavior. The only proper use for
+@samp{--enable} is for questions of whether to build part of the program
+or exclude it.
+
+@item --with-@var{package}
+@c @r{[}=@var{parameter}@r{]}
+The package @var{package} will be installed, so configure this package
+to work with @var{package}.
+
+@c Giving an optional @var{parameter} of
+@c @samp{no} should omit @var{package}, if it is used by default.
+
+Possible values of @var{package} include @samp{x}, @samp{x-toolkit},
+@samp{gnu-as} (or @samp{gas}), @samp{gnu-ld}, @samp{gnu-libc}, and
+@samp{gdb}.
+
+Do not use a @samp{--with} option to specify the file name to use to
+find certain files. That is outside the scope of what @samp{--with}
+options are for.
+
+@item --nfp
+The target machine has no floating point processor.
+
+@item --gas
+The target machine assembler is GAS, the GNU assembler.
+This is obsolete; users should use @samp{--with-gnu-as} instead.
+
+@item --x
+The target machine has the X Window System installed.
+This is obsolete; users should use @samp{--with-x} instead.
+@end table
+
+All @code{configure} scripts should accept all of these ``detail''
+options, whether or not they make any difference to the particular
+package at hand. In particular, they should accept any option that
+starts with @samp{--with-} or @samp{--enable-}. This is so users will
+be able to configure an entire GNU source tree at once with a single set
+of options.
+
+You will note that the categories @samp{--with-} and @samp{--enable-}
+are narrow: they @strong{do not} provide a place for any sort of option
+you might think of. That is deliberate. We want to limit the possible
+configuration options in GNU software. We do not want GNU programs to
+have idiosyncratic configuration options.
+
+Packages that perform part of the compilation process may support cross-compilation.
+In such a case, the host and target machines for the program may be
+different. The @code{configure} script should normally treat the
+specified type of system as both the host and the target, thus producing
+a program which works for the same type of machine that it runs on.
+
+The way to build a cross-compiler, cross-assembler, or what have you, is
+to specify the option @samp{--host=@var{hosttype}} when running
+@code{configure}. This specifies the host system without changing the
+type of target system. The syntax for @var{hosttype} is the same as
+described above.
+
+Bootstrapping a cross-compiler requires compiling it on a machine other
+than the host it will run on. Compilation packages accept a
+configuration option @samp{--build=@var{hosttype}} for specifying the
+configuration on which you will compile them, in case that is different
+from the host.
+
+Programs for which cross-operation is not meaningful need not accept the
+@samp{--host} option, because configuring an entire operating system for
+cross-operation is not a meaningful thing.
+
+Some programs have ways of configuring themselves automatically. If
+your program is set up to do this, your @code{configure} script can simply
+ignore most of its arguments.
+
+@comment The makefile standards are in a separate file that is also
+@comment included by make.texinfo. Done by roland@gnu.ai.mit.edu on 1/6/93.
+@comment For this document, turn chapters into sections, etc.
+@lowersections
+@include make-stds.texi
+@raisesections
+
@node Releases
-@chapter Making Releases
+@section Making Releases
Package the distribution of Foo version 69.96 in a gzipped tar file
named @file{foo-69.96.tar.gz}. It should unpack into a subdirectory
to include non-source files in the distribution, provided they are
up-to-date and machine-independent, so that building the distribution
normally will never modify them. We commonly include non-source files
-produced by Bison, Lex, @TeX{}, and Makeinfo; this helps avoid
+produced by Bison, @code{lex}, @TeX{}, and @code{makeinfo}; this helps avoid
unnecessary dependencies between our distributions, so that users can
install whichever packages they want to install.
systems cannot handle this and that prevents unpacking the
distribution.
-Try to make sure that all the file names will be unique on MS-DOG. A
-name on MS-DOG consists of up to 8 characters, optionally followed by a
-period and up to three characters. MS-DOG will truncate extra
+Try to make sure that all the file names will be unique on MS-DOS. A
+name on MS-DOS consists of up to 8 characters, optionally followed by a
+period and up to three characters. MS-DOS will truncate extra
characters both before and after the period. Thus,
@file{foobarhacker.c} and @file{foobarhacker.o} are not ambiguous; they
are truncated to @file{foobarha.c} and @file{foobarha.o}, which are
distinct.
Include in your distribution a copy of the @file{texinfo.tex} you used
-to test print any @file{*.texinfo} files.
+to test print any @file{*.texinfo} or @file{*.texi} files.
Likewise, if your program uses small GNU software packages like regex,
getopt, obstack, or termcap, include them in the distribution file.
projects / thirdparty / autoconf.git / commitdiff
