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\input texinfo                  @c -*- Texinfo -*-
@comment %**start of header (This is for running Texinfo on a region.)
@setfilename libc.info
@settitle The GNU C Library
@setchapternewpage odd

@comment Tell install-info what to do.
@dircategory GNU libraries
@direntry
* Libc: (libc).                 C library.
@end direntry

@c This tells texinfo.tex to use the real section titles in xrefs in
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@c sold 0.06/1.09, print run out 21may96
@set EDITION 0.07 DRAFT
@set VERSION 2.00 Beta
@set UPDATED 03 Apr 1998
@set ISBN 1-882114-53-1

@ifinfo
This file documents the GNU C library.

This is Edition @value{EDITION}, last updated @value{UPDATED},
of @cite{The GNU C Library Reference Manual}, for Version @value{VERSION}.

Copyright (C) 1993, '94, '95, '96, '97, '98 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).

@end ignore
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that the
section entitled ``GNU Library General Public License'' is included
exactly as in the original, and provided that the entire resulting
derived work is distributed under the terms of a permission notice
identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that the text of the translation of the section entitled ``GNU
Library General Public License'' must be approved for accuracy by the
Foundation.
@end ifinfo

@iftex
@shorttitlepage The GNU C Library Reference Manual
@end iftex
@titlepage
@center @titlefont{The GNU C Library}
@sp 1
@center @titlefont{Reference Manual}
@sp 2
@center Sandra Loosemore
@center with
@center Richard M. Stallman, Roland McGrath, Andrew Oram, and Ulrich Drepper
@sp 3
@center Edition @value{EDITION}
@sp 1
@center last updated @value{UPDATED}
@sp 1
@center for version @value{VERSION}
@page
@vskip 0pt plus 1filll
Copyright @copyright{} 1993, '94, '95, '96, '97, '98 Free Software Foundation, Inc.
@sp 2
Published by the Free Software Foundation @*
59 Temple Place -- Suite 330, @*
Boston, MA 02111-1307 USA @*
Printed copies are available for $50 each. @*
ISBN @value{ISBN} @*

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that the
section entitled ``GNU Library General Public License'' is included
exactly as in the original, and provided that the entire resulting
derived work is distributed under the terms of a permission notice
identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that the text of the translation of the section entitled ``GNU
Library General Public License'' must be approved for accuracy by the
Foundation.
@end titlepage
@page

@ifinfo
@node Top, Introduction, (dir), (dir)
@top Main Menu
This is Edition @value{EDITION}, last updated @value{UPDATED}, of
@cite{The GNU C Library Reference Manual}, for Version @value{VERSION}
of the GNU C Library.
@end ifinfo


@menu
* Introduction::                Purpose of the GNU C Library.
* Error Reporting::             How the GNU Library functions report
                                 error conditions.
* Memory Allocation::           Your program can allocate memory dynamically
                                 and manipulate it via pointers.
* Character Handling::          Character testing and conversion functions.
* String and Array Utilities::  Utilities for copying and comparing
                                 strings and arrays.
* Extended Characters::         Support for extended character sets.
* Locales::                     The country and language can affect
                                 the behavior of library functions.
* Message Translation::         How to make the program speak the users
                                 language.
* Searching and Sorting::       General searching and sorting functions.
* Pattern Matching::            Matching wildcards and regular expressions,
                                 and shell-style ``word expansion''.
* I/O Overview::                Introduction to the I/O facilities.
* Streams: I/O on Streams.      High-level, portable I/O facilities.
* Low-Level I/O::               Low-level, less portable I/O.
* File System Interface::       Functions for manipulating files.
* Pipes and FIFOs::             A simple interprocess communication mechanism.
* Sockets::                     A more complicated interprocess communication
                                 mechanism, with support for networking.
* Low-Level Terminal Interface::How to change the characteristics
                                 of a terminal device.
* Mathematics::                 Math functions (transcendental functions,
                                 random numbers, absolute value, etc.).
* Arithmetic::                  Low-level arithmetic functions.
* Date and Time::               Functions for getting the date and time,
                                 and for conversion between formats.
* Non-Local Exits::             The @code{setjmp} and @code{longjmp} facilities.
* Signal Handling::             All about signals; how to send them,
                                 block them, and handle them.
* Process Startup::             Writing the beginning and end of your program.
* Processes::                   How to create processes and run other programs.
* Job Control::                 All about process groups and sessions.
* Name Service Switch::         Accessing the various system databases.
* Users and Groups::            How users are identified and classified.
* System Information::          Getting information about the
                                 hardware and software configuration
                                 of the machine a program runs on.
* System Configuration::        Parameters describing operating system limits.

Appendices

* Language Features::           C language features provided by the library.

* Library Summary::             A summary showing the syntax, header file,
                                 and derivation of each library feature.
* Installation::                How to install the GNU C library.
* Maintenance::                 How to enhance and port the GNU C Library.
* Contributors::                Who wrote what parts of the GNU C Library.
* Copying::                     The GNU Library General Public License says
                                 how you can copy and share the GNU C Library.

Indices

* Concept Index::               Index of concepts and names.
* Type Index::                  Index of types and type qualifiers.
* Function Index::              Index of functions and function-like macros.
* Variable Index::              Index of variables and variable-like macros.
* File Index::                  Index of programs and files.

 --- The Detailed Node Listing ---

Introduction

* Getting Started::             Getting Started
* Standards and Portability::   Standards and Portability
* Using the Library::           Using the Library
* Roadmap to the Manual::       Roadmap to the Manual

Standards and Portability

* ISO C::                       The American National Standard for the
                                 C programming language.
* POSIX::                       The ISO/IEC 9945 (aka IEEE 1003) standards
                                 for operating systems.
* Berkeley Unix::               BSD and SunOS.
* SVID::                        The System V Interface Description.

Using the Library

* Header Files::                How to use the header files in your programs.
* Macro Definitions::           Some functions in the library may really
                                 be implemented as macros.
* Reserved Names::              The C standard reserves some names for
                                 the library, and some for users.
* Feature Test Macros::         How to control what names are defined.

Error Reporting

* Checking for Errors::         How errors are reported by library functions.
* Error Codes::                 What all the error codes are.
* Error Messages::              Mapping error codes onto error messages.

Memory Allocation

* Memory Concepts::             An introduction to concepts and terminology.
* Dynamic Allocation and C::    How to get different kinds of allocation in C.
* Unconstrained Allocation::    The @code{malloc} facility allows fully general
                                 dynamic allocation.
* Obstacks::                    Obstacks are less general than malloc
                                 but more efficient and convenient.
* Variable Size Automatic::     Allocation of variable-sized blocks
                                 of automatic storage that are freed when the
                                 calling function returns.
* Relocating Allocator::        Waste less memory, if you can tolerate
                                 automatic relocation of the blocks you get.

Unconstrained Allocation

* Basic Allocation::            Simple use of @code{malloc}.
* Malloc Examples::             Examples of @code{malloc}.  @code{xmalloc}.
* Freeing after Malloc::        Use @code{free} to free a block you
                                 got with @code{malloc}.
* Changing Block Size::         Use @code{realloc} to make a block
                                 bigger or smaller.
* Allocating Cleared Space::    Use @code{calloc} to allocate a
                                 block and clear it.
* Efficiency and Malloc::       Efficiency considerations in use of
                                 these functions.
* Aligned Memory Blocks::       Allocating specially aligned memory:
                                 @code{memalign} and @code{valloc}.
* Heap Consistency Checking::   Automatic checking for errors.
* Hooks for Malloc::            You can use these hooks for debugging
                                 programs that use @code{malloc}.
* Statistics of Malloc::        Getting information about how much
                                 memory your program is using.
* Summary of Malloc::           Summary of @code{malloc} and related functions.

Obstacks

* Creating Obstacks::           How to declare an obstack in your program.
* Preparing for Obstacks::      Preparations needed before you can
                                 use obstacks.
* Allocation in an Obstack::    Allocating objects in an obstack.
* Freeing Obstack Objects::     Freeing objects in an obstack.
* Obstack Functions::           The obstack functions are both
                                 functions and macros.
* Growing Objects::             Making an object bigger by stages.
* Extra Fast Growing::          Extra-high-efficiency (though more
                                 complicated) growing objects.
* Status of an Obstack::        Inquiries about the status of an obstack.
* Obstacks Data Alignment::     Controlling alignment of objects in obstacks.
* Obstack Chunks::              How obstacks obtain and release chunks.
                                Efficiency considerations.
* Summary of Obstacks::

Automatic Storage with Variable Size

* Alloca Example::              Example of using @code{alloca}.
* Advantages of Alloca::        Reasons to use @code{alloca}.
* Disadvantages of Alloca::     Reasons to avoid @code{alloca}.
* GNU C Variable-Size Arrays::  Only in GNU C, here is an alternative
                                 method of allocating dynamically and
                                 freeing automatically.
Relocating Allocator

* Relocator Concepts::          How to understand relocating allocation.
* Using Relocator::             Functions for relocating allocation.

Character Handling

* Classification of Characters::Testing whether characters are
                                 letters, digits, punctuation, etc.
* Case Conversion::             Case mapping, and the like.

String and Array Utilities

* Representation of Strings::   Introduction to basic concepts.
* String/Array Conventions::    Whether to use a string function or an
                                 arbitrary array function.
* String Length::               Determining the length of a string.
* Copying and Concatenation::   Functions to copy the contents of strings
                                 and arrays.
* String/Array Comparison::     Functions for byte-wise and character-wise
                                 comparison.
* Collation Functions::         Functions for collating strings.
* Search Functions::            Searching for a specific element or substring.
* Finding Tokens in a String::  Splitting a string into tokens by looking
                                 for delimiters.

Extended Characters

* Extended Char Intro::         Multibyte codes versus wide characters.
* Locales and Extended Chars::  The locale selects the character codes.
* Multibyte Char Intro::        How multibyte codes are represented.
* Wide Char Intro::             How wide characters are represented.
* Wide String Conversion::      Converting wide strings to multibyte code
                                   and vice versa.
* Length of Char::              how many bytes make up one multibyte char.
* Converting One Char::         Converting a string character by character.
* Example of Conversion::       Example showing why converting
                                   one character at a time may be useful.
* Shift State::                 Multibyte codes with "shift characters".

Locales and Internationalization

* Effects of Locale::           Actions affected by the choice of locale.
* Choosing Locale::             How the user specifies a locale.
* Locale Categories::           Different purposes for which
                                 you can select a locale.
* Setting the Locale::          How a program specifies the locale.
* Standard Locales::            Locale names available on all systems.
* Numeric Formatting::          How to format numbers for the chosen locale.

Message Translation

* Message catalogs a la X/Open::  The @code{catgets} family of functions.
* The Uniforum approach::         The @code{gettext} family of functions.

Searching and Sorting

* Comparison Functions::        Defining how to compare two objects.
                                Since the sort and search facilities are
                                general, you have to specify the ordering.
* Array Search Function::       The @code{bsearch} function.
* Array Sort Function::         The @code{qsort} function.
* Search/Sort Example::         An example program.

Pattern Matching

* Wildcard Matching::    Matching a wildcard pattern against a single string.
* Globbing::             Finding the files that match a wildcard pattern.
* Regular Expressions::  Matching regular expressions against strings.
* Word Expansion::       Expanding shell variables, nested commands,
                          arithmetic, and wildcards.
                          This is what the shell does with shell commands.

I/O Overview

* I/O Concepts::                Some basic information and terminology.
* File Names::                  How to refer to a file.

I/O Concepts

* Streams and File Descriptors:: The GNU Library provides two ways
                                  to access the contents of files.
* File Position::               The number of bytes from the
                                 beginning of the file.

File Names

* Directories::                 Directories contain entries for files.
* File Name Resolution::        A file name specifies how to look up a file.
* File Name Errors::            Error conditions relating to file names.
* File Name Portability::       File name portability and syntax issues.

I/O on Streams

* Streams::                     About the data type representing a stream.
* Standard Streams::            Streams to the standard input and output
                                 devices are created for you.
* Opening Streams::             How to create a stream to talk to a file.
* Closing Streams::             Close a stream when you are finished with it.
* Simple Output::               Unformatted output by characters and lines.
* Character Input::             Unformatted input by characters and words.
* Line Input::                  Reading a line or a record from a stream.
* Unreading::                   Peeking ahead/pushing back input just read.
* Formatted Output::            @code{printf} and related functions.
* Customizing Printf::          You can define new conversion specifiers for
                                 @code{printf} and friends.
* Formatted Input::             @code{scanf} and related functions.
* Block Input/Output::          Input and output operations on blocks of data.
* EOF and Errors::              How you can tell if an I/O error happens.
* Binary Streams::              Some systems distinguish between text files
                                 and binary files.
* File Positioning::            About random-access streams.
* Portable Positioning::        Random access on peculiar ISO C systems.
* Stream Buffering::            How to control buffering of streams.
* Temporary Files::             How to open a temporary file.
* Other Kinds of Streams::      Other Kinds of Streams

Unreading

* Unreading Idea::              An explanation of unreading with pictures.
* How Unread::                  How to call @code{ungetc} to do unreading.

Formatted Output

* Formatted Output Basics::     Some examples to get you started.
* Output Conversion Syntax::    General syntax of conversion specifications.
* Table of Output Conversions:: Summary of output conversions, what they do.
* Integer Conversions::         Details of formatting integers.
* Floating-Point Conversions::  Details of formatting floating-point numbers.
* Other Output Conversions::    Details about formatting of strings,
                                 characters, pointers, and the like.
* Formatted Output Functions::  Descriptions of the actual functions.
* Variable Arguments Output::   @code{vprintf} and friends.
* Parsing a Template String::   What kinds of arguments does
                                 a given template call for?

Customizing Printf

* Registering New Conversions::
* Conversion Specifier Options::
* Defining the Output Handler::
* Printf Extension Example::

Formatted Input

* Formatted Input Basics::      Some basics to get you started.
* Input Conversion Syntax::     Syntax of conversion specifications.
* Table of Input Conversions::  Summary of input conversions and what they do.
* Numeric Input Conversions::   Details of conversions for reading numbers.
* String Input Conversions::    Details of conversions for reading strings.
* Other Input Conversions::     Details of miscellaneous other conversions.
* Formatted Input Functions::   Descriptions of the actual functions.
* Variable Arguments Input::    @code{vscanf} and friends.

Stream Buffering

* Buffering Concepts::          Terminology is defined here.
* Flushing Buffers::            How to ensure that output buffers are flushed.
* Controlling Buffering::       How to specify what kind of buffering to use.

Other Kinds of Streams

* String Streams::
* Custom Streams::

Programming Your Own Custom Streams

* Streams and Cookies::
* Hook Functions::

Low-Level I/O

* Opening and Closing Files::   How to open and close file descriptors.
* I/O Primitives::              Reading and writing data.
* File Position Primitive::     Setting a descriptor's file position.
* Descriptors and Streams::     Converting descriptor to stream or vice-versa.
* Stream/Descriptor Precautions::  Precautions needed if you use both
                                    descriptors and streams.
* Waiting for I/O::             How to check for input or output
                                 on multiple file descriptors.
* Control Operations::          Various other operations on file descriptors.
* Duplicating Descriptors::     Fcntl commands for duplicating descriptors.
* Descriptor Flags::            Fcntl commands for manipulating flags
                                 associated with file descriptors.
* File Status Flags::           Fcntl commands for manipulating flags
                                 associated with open files.
* File Locks::                  Fcntl commands for implementing file locking.
* Interrupt Input::             Getting a signal when input arrives.

File System Interface

* Working Directory::           This is used to resolve relative file names.
* Accessing Directories::       Finding out what files a directory contains.
* Hard Links::                  Adding alternate names to a file.
* Symbolic Links::              A file that ``points to'' a file name.
* Deleting Files::              How to delete a file, and what that means.
* Renaming Files::              Changing a file's name.
* Creating Directories::        A system call just for creating a directory.
* File Attributes::             Attributes of individual files.
* Making Special Files::        How to create special files.

Accessing Directories

* Directory Entries::           Format of one directory entry.
* Opening a Directory::         How to open a directory stream.
* Reading/Closing Directory::   How to read directory entries from the stream.
* Simple Directory Lister::     A very simple directory listing program.
* Random Access Directory::     Rereading part of the directory
                                  already read with the same stream.

File Attributes

* Attribute Meanings::          The names of the file attributes,
                                 and what their values mean.
* Reading Attributes::          How to read the attributes of a file.
* Testing File Type::           Distinguishing ordinary files,
                                 directories, links...
* File Owner::                  How ownership for new files is determined,
                                 and how to change it.
* Permission Bits::             How information about a file's access mode
                                 is stored.
* Access Permission::           How the system decides who can access a file.
* Setting Permissions::         How permissions for new files are assigned,
                                 and how to change them.
* Testing File Access::         How to find out if your process can
                                 access a file.
* File Times::                  About the time attributes of a file.

Pipes and FIFOs

* Creating a Pipe::             Making a pipe with the @code{pipe} function.
* Pipe to a Subprocess::        Using a pipe to communicate with a child.
* FIFO Special Files::          Making a FIFO special file.

Sockets

* Socket Concepts::             Basic concepts you need to know about.
* Communication Styles::        Stream communication, datagrams, and others.
* Socket Addresses::            How socket names (``addresses'') work.
* Local Namespace::             Details about the local namespace.
* Internet Namespace::          Details about the Internet namespace.
* Open/Close Sockets::          Creating sockets and destroying them.
* Connections::                 Operations on sockets with connection state.
* Datagrams::                   Operations on datagram sockets.
* Socket Options::              Miscellaneous low-level socket options.
* Networks Database::           Accessing the database of network names.

Socket Addresses

* Address Formats::             About @code{struct sockaddr}.
* Setting Address::             Binding an address to a socket.
* Reading Address::             Reading the address of a socket.

Internet Domain

* Internet Address Formats::    How socket addresses are specified in the
                                 Internet namespace.
* Host Addresses::              All about host addresses of Internet hosts.
* Protocols Database::          Referring to protocols by name.
* Services Database::           Ports may have symbolic names.
* Byte Order::                  Different hosts may use different byte
                                 ordering conventions; you need to
                                 canonicalize host address and port number.
* Inet Example::                Putting it all together.

Host Addresses

* Abstract Host Addresses::             What a host number consists of.
* Data type: Host Address Data Type.    Data type for a host number.
* Functions: Host Address Functions.    Functions to operate on them.
* Names: Host Names.                    Translating host names to host numbers.

Open/Close Sockets

* Creating a Socket::           How to open a socket.
* Closing a Socket::            How to close a socket.
* Socket Pairs::                These are created like pipes.

Connections

* Connecting::                  What the client program must do.
* Listening::                   How a server program waits for requests.
* Accepting Connections::       What the server does when it gets a request.
* Who is Connected::            Getting the address of the
                                 other side of a connection.
* Transferring Data::           How to send and receive data.
* Byte Stream Example::         An example client for communicating over a
                                 byte stream socket in the Internet namespace.
* Server Example::              A corresponding server program.
* Out-of-Band Data::            This is an advanced feature.

Transferring Data

* Sending Data::                Sending data with @code{write}.
* Receiving Data::              Reading data with @code{read}.
* Socket Data Options::         Using @code{send} and @code{recv}.

Datagrams

* Sending Datagrams::           Sending packets on a datagram socket.
* Receiving Datagrams::         Receiving packets on a datagram socket.
* Datagram Example::            An example program: packets sent over a
                                 datagram stream in the local namespace.
* Example Receiver::            Another program, that receives those packets.

Socket Options

* Socket Option Functions::     The basic functions for setting and getting
                                 socket options.
* Socket-Level Options::        Details of the options at the socket level.

Low-Level Terminal Interface

* Is It a Terminal::            How to determine if a file is a terminal
                                 device, and what its name is.
* I/O Queues::                  About flow control and typeahead.
* Canonical or Not::            Two basic styles of input processing.
* Terminal Modes::              How to examine and modify flags controlling
                                 terminal I/O: echoing, signals, editing.
* Line Control::                Sending break sequences, clearing  buffers...
* Noncanon Example::            How to read single characters without echo.

Terminal Modes

* Mode Data Types::             The data type @code{struct termios} and related types.
* Mode Functions::              Functions to read and set terminal attributes.
* Setting Modes::               The right way to set attributes reliably.
* Input Modes::                 Flags controlling low-level input handling.
* Output Modes::                Flags controlling low-level output handling.
* Control Modes::               Flags controlling serial port behavior.
* Local Modes::                 Flags controlling high-level input handling.
* Line Speed::                  How to read and set the terminal line speed.
* Special Characters::          Characters that have special effects,
                                 and how to change them.
* Noncanonical Input::          Controlling how long to wait for input.

Special Characters

* Editing Characters::
* Signal Characters::
* Start/Stop Characters::

Mathematics

* Domain and Range Errors::     How overflow conditions and the
                                 like are reported.
* Not a Number::                Making NANs and testing for NANs.
* Trig Functions::              Sine, cosine, and tangent.
* Inverse Trig Functions::      Arc sine, arc cosine, and arc tangent.
* Exponents and Logarithms::    Also includes square root.
* Hyperbolic Functions::        Hyperbolic sine and friends.
* Pseudo-Random Numbers::       Functions for generating pseudo-random numbers.
* Absolute Value::              Absolute value functions.

Pseudo-Random Numbers

* ISO Random::                  @code{rand} and friends.
* BSD Random::                  @code{random} and friends.

Low-Level Arithmetic Functions

* Normalization Functions::     Hacks for radix-2 representations.
* Rounding and Remainders::     Determining the integer and
                                 fractional parts of a float.
* Integer Division::            Functions for performing integer division.
* Parsing of Numbers::          Functions for ``reading'' numbers from strings.
* Predicates on Floats::        Some miscellaneous test functions.

Parsing of Numbers

* Parsing of Integers::         Functions for conversion of integer values.
* Parsing of Floats::           Functions for conversion of floating-point.

Date and Time

* Processor Time::              Measures processor time used by a program.
* Calendar Time::               Manipulation of ``real'' dates and times.
* Setting an Alarm::            Sending a signal after a specified time.
* Sleeping::                    Waiting for a period of time.

Processor Time

* Basic CPU Time::              The @code{clock} function.
* Detailed CPU Time::           The @code{times} function.

Calendar Time

* Simple Calendar Time::        Facilities for manipulating calendar time.
* High-Resolution Calendar::    A time representation with greater precision.
* Broken-down Time::            Facilities for manipulating local time.
* Formatting Date and Time::    Converting times to strings.
* TZ Variable::                 How users specify the time zone.
* Time Zone Functions::         Functions to examine or specify the time zone.
* Time Functions Example::      An example program showing use of some of
                                 the time functions.

Signal Handling

* Concepts of Signals::         Introduction to the signal facilities.
* Standard Signals::            Particular kinds of signals with standard
                                 names and meanings.
* Signal Actions::              Specifying what happens when a particular
                                 signal is delivered.
* Defining Handlers::           How to write a signal handler function.
* Generating Signals::          How to send a signal to a process.
* Blocking Signals::            Making the system hold signals temporarily.
* Waiting for a Signal::        Suspending your program until a signal arrives.
* Signal Stack::                Using a Separate Signal Stack
* BSD Signal Handling::         Additional functions for backward
                                 compatibility with BSD.

Basic Concepts of Signals

* Kinds of Signals::            Some examples of what can cause a signal.
* Signal Generation::           Concepts of why and how signals occur.
* Delivery of Signal::          Concepts of what a signal does to the process.

Standard Signals

* Program Error Signals::       Used to report serious program errors.
* Termination Signals::         Used to interrupt and/or terminate the program.
* Alarm Signals::               Used to indicate expiration of timers.
* Asynchronous I/O Signals::    Used to indicate input is available.
* Job Control Signals::         Signals used to support job control.
* Operation Error Signals::     Used to report operational system errors.
* Miscellaneous Signals::       Miscellaneous Signals.
* Signal Messages::             Printing a message describing a signal.

Specifying Signal Actions

* Basic Signal Handling::       The simple @code{signal} function.
* Advanced Signal Handling::    The more powerful @code{sigaction} function.
* Signal and Sigaction::        How those two functions interact.
* Sigaction Function Example::  An example of using the sigaction function.
* Flags for Sigaction::         Specifying options for signal handling.
* Initial Signal Actions::      How programs inherit signal actions.

Defining Signal Handlers

* Handler Returns::
* Termination in Handler::
* Longjmp in Handler::
* Signals in Handler::
* Nonreentrancy::
* Atomic Data Access::

Generating Signals

* Signaling Yourself::          Signaling Yourself
* Signaling Another Process::   Send a signal to another process.
* Permission for kill::         Permission for using @code{kill}
* Kill Example::                Using @code{kill} for Communication

Blocking Signals

* Why Block::                   The purpose of blocking signals.
* Signal Sets::                 How to specify which signals to block.
* Process Signal Mask::         Blocking delivery of signals to your
                                 process during normal execution.
* Testing for Delivery::        Blocking to Test for Delivery of a Signal
* Blocking for Handler::        Blocking additional signals while a
                                 handler is being run.
* Checking for Pending Signals::Checking for Pending Signals
* Remembering a Signal::        How you can get almost the same effect
                                 as blocking a signal, by handling it
                                 and setting a flag to be tested later.

Waiting for a Signal

* Using Pause::                 The simple way, using @code{pause}.
* Pause Problems::              Why the simple way is often not very good.
* Sigsuspend::                  Reliably waiting for a specific signal.

BSD Signal Handling

* BSD Handler::                 BSD Function to Establish a Handler.
* Blocking in BSD::             BSD Functions for Blocking Signals

Process Startup and Termination

* Program Arguments::           Parsing your program's command-line arguments.
* Environment Variables::       How to access parameters inherited from
                                 a parent process.
* Program Termination::         How to cause a process to terminate and
                                 return status information to its parent.

Program Arguments

* Argument Syntax::             By convention, options start with a hyphen.
* Parsing Program Arguments::   Ways to parse program options and arguments.

Parsing Program Arguments

* Getopt::                      Parsing program options using @code{getopt}.
* Argp::                        Parsing program options using @code{argp_parse}.
* Suboptions::                  Some programs need more detailed options.
* Suboptions Example::          This shows how it could be done for @code{mount}.

Environment Variables

* Environment Access::          How to get and set the values of
                                 environment variables.
* Standard Environment::        These environment variables have
                                 standard interpretations.

Program Termination

* Normal Termination::          If a program calls @code{exit}, a
                                 process terminates normally.
* Exit Status::                 The @code{exit status} provides information
                                 about why the process terminated.
* Cleanups on Exit::            A process can run its own cleanup
                                 functions upon normal termination.
* Aborting a Program::          The @code{abort} function causes
                                 abnormal program termination.
* Termination Internals::       What happens when a process terminates.


Child Processes

* Running a Command::           The easy way to run another program.
* Process Creation Concepts::   An overview of the hard way to do it.
* Process Identification::      How to get the process ID of a process.
* Creating a Process::          How to fork a child process.
* Executing a File::            How to make a child execute another program.
* Process Completion::          How to tell when a child process has completed.
* Process Completion Status::   How to interpret the status value
                                 returned from a child process.
* BSD Wait Functions::          More functions, for backward compatibility.
* Process Creation Example::    A complete example program.

Job Control

* Concepts of Job Control ::    Concepts of Job Control
* Job Control is Optional::     Not all POSIX systems support job control.
* Controlling Terminal::        How a process gets its controlling terminal.
* Access to the Terminal::      How processes share the controlling terminal.
* Orphaned Process Groups::     Jobs left after the user logs out.
* Implementing a Shell::        What a shell must do to implement job control.
* Functions for Job Control::   Functions to control process groups.

Implementing a Job Control Shell

* Data Structures::             Introduction to the sample shell.
* Initializing the Shell::      What the shell must do to take
                                 responsibility for job control.
* Launching Jobs::              Creating jobs to execute commands.
* Foreground and Background::   Putting a job in foreground of background.
* Stopped and Terminated Jobs:: Reporting job status.
* Continuing Stopped Jobs::     How to continue a stopped job in
                                 the foreground or background.
* Missing Pieces::              Other parts of the shell.

Functions for Job Control

* Identifying the Terminal::    Determining the controlling terminal's name.
* Process Group Functions::     Functions for manipulating process groups.
* Terminal Access Functions::   Functions for controlling terminal access.

Name Service Switch

* NSS Basics::                  What is this NSS good for.
* NSS Configuration File::      Configuring NSS.
* NSS Module Internals::        How does it work internally.
* Extending NSS::               What to do to add services or databases.

Users and Groups

* User and Group IDs::          Each user and group has a unique numeric ID.
* Process Persona::             The user IDs and group IDs of a process.
* Why Change Persona::          Why a program might need to change
                                 its user and/or group IDs.
* How Change Persona::          Restrictions on changing user and group IDs.
* Reading Persona::             Examining the process's user and group IDs.
* Setting User ID::
* Setting Groups::
* Enable/Disable Setuid::
* Setuid Program Example::      Setuid Program Example
* Tips for Setuid::
* Who Logged In::               Getting the name of the user who logged in,
                                 or of the real user ID of the current process.

* User Database::               Functions and data structures for
                                 accessing the user database.
* Group Database::              Functions and data structures for
                                 accessing the group database.
* Database Example::            Example program showing use of database
                                 inquiry functions.

User Database

* User Data Structure::
* Lookup User::
* Scanning All Users::          Scanning the List of All Users
* Writing a User Entry::

Group Database

* Group Data Structure::
* Lookup Group::
* Scanning All Groups::         Scanning the List of All Groups

System Information

* Host Identification::         Determining the name of the machine.
* Hardware/Software Type ID::   Determining the hardware type and
                                 operating system type.

System Configuration Limits

* General Limits::              Constants and functions that describe
                                 various process-related limits that have
                                 one uniform value for any given machine.
* System Options::              Optional POSIX features.
* Version Supported::           Version numbers of POSIX.1 and POSIX.2.
* Sysconf::                     Getting specific configuration values
                                 of general limits and system options.
* Minimums::                    Minimum values for general limits.

* Limits for Files::            Size limitations on individual files.
                                 These can vary between file systems
                                  or even from file to file.
* Options for Files::           Optional features that some files may support.
* File Minimums::               Minimum values for file limits.
* Pathconf::                    Getting the limit values for a particular file.

* Utility Limits::              Capacity limits of POSIX.2 utility programs.
* Utility Minimums::            Minimum allowable values of those limits.

* String Parameters::           Getting the default search path.

Library Facilities that are Part of the C Language

* Consistency Checking::        Using @code{assert} to abort
                                 if something ``impossible'' happens.
* Variadic Functions::          Defining functions with varying
                                 numbers of arguments.
* Null Pointer Constant::       The macro @code{NULL}.
* Important Data Types::        Data types for object sizes.
* Data Type Measurements::      Parameters of data type representations.

Variadic Functions

* Why Variadic::                Reasons for making functions take
                                 variable arguments.
* How Variadic::                How to define and call variadic functions.
* Argument Macros::             Detailed specification of the macros
                                 for accessing variable arguments.
* Variadic Example::            A complete example.

How Variadic Functions are Defined and Used

* Variadic Prototypes::         How to make a prototype for a function
                                 with variable arguments.
* Receiving Arguments::         Steps you must follow to access the
                                 optional argument values.
* How Many Arguments::          How to decide whether there are more arguments.
* Calling Variadics::           Things you need to know about calling
                                 variable arguments functions.

Data Type Measurements

* Width of Type::               How many bits does an integer type hold?
* Range of Type::               What are the largest and smallest values
                                 that an integer type can hold?
* Floating Type Macros::        Parameters that measure floating-point types.
* Structure Measurement::       Getting measurements on structure types.

Floating Type Macros

* Floating Point Concepts::     Definitions of terminology.
* Floating Point Parameters::   Dimensions, limits of floating point types.
* IEEE Floating Point::         How one common representation is described.

Library Maintenance

* Installation::                How to configure, compile and install
                                 the GNU C library.
* Reporting Bugs::              How to report bugs (if you want to
                                 get them fixed) and other troubles
                                 you may have with the GNU C library.
@c * Traditional C Compatibility::  Using the GNU C library with non-ANSI
@c                                          C compilers.

Porting the GNU C Library

* Hierarchy Conventions::       How the @file{sysdeps} hierarchy is
                                 layed out.
* Porting to Unix::             Porting the library to an average
                                 Unix-like system.
@end menu


@comment Includes of all the individual chapters.
@include intro.texi
@include errno.texi
@include memory.texi
@include ctype.texi
@include string.texi
@include mbyte.texi
@include locale.texi
@include message.texi
@include search.texi
@include pattern.texi
@include io.texi
@include stdio.texi
@include llio.texi
@include filesys.texi
@include pipe.texi
@include socket.texi
@include terminal.texi
@include math.texi
@include arith.texi
@include time.texi
@include setjmp.texi
@include signal.texi
@include startup.texi
@include process.texi
@include job.texi
@include nss.texi
@include users.texi
@include sysinfo.texi
@include conf.texi

@comment Includes of the appendices.
@include lang.texi
@include header.texi
@include install.texi
@include maint.texi
@include contrib.texi


@set lgpl-appendix
@node Copying, Concept Index, Contributors, Top
@include lgpl.texinfo


@node Concept Index, Type Index, Copying, Top
@unnumbered Concept Index

@printindex cp

@node Type Index, Function Index, Concept Index, Top
@unnumbered Type Index

@printindex tp

@node Function Index, Variable Index, Type Index, Top
@unnumbered Function and Macro Index

@printindex fn

@node Variable Index, File Index, Function Index, Top
@unnumbered Variable and Constant Macro Index

@printindex vr

@node File Index, , Variable Index, Top
@unnumbered Program and File Index

@printindex pg


@shortcontents
@contents
@bye