Warnings about @samp{syntax} are enabled by default, and the environment
variable @env{WARNINGS}, a comma separated list of categories, is
-honored as well. Passing @samp{-W @var{category}} will actually behave as if
-you had passed @samp{--warnings=syntax,$WARNINGS,@var{category}}. If
+honored as well. Passing @option{-W @var{category}} will actually behave as if
+you had passed @option{--warnings=syntax,$WARNINGS,@var{category}}. If
you want to disable the defaults and @env{WARNINGS}, but (for example)
enable the warnings about obsolete constructs, you would use @option{-W
none,obsolete}.
Warnings about @samp{syntax} are enabled by default, and the environment
variable @env{WARNINGS}, a comma separated list of categories, is
-honored as well. Passing @samp{-W @var{category}} will actually behave as if
-you had passed @samp{--warnings=syntax,$WARNINGS,@var{category}}. If
+honored as well. Passing @option{-W @var{category}} will actually behave as if
+you had passed @option{--warnings=syntax,$WARNINGS,@var{category}}. If
you want to disable the defaults and @env{WARNINGS}, but (for example)
enable the warnings about obsolete constructs, you would use @option{-W
none,obsolete}.
in @file{configure} and hard-coding it in Makefiles using
e.g., @samp{AC_DEFINE_UNQUOTED([DATADIR], ["$datadir"], [Data directory.])},
you should add
-@samp{-DDATADIR="$(datadir)"} to your @code{CPPFLAGS}.
+@option{-DDATADIR="$(datadir)"} to your @code{CPPFLAGS}.
Similarly, you should not rely on @code{AC_CONFIG_FILES} to replace
@code{datadir} and friends in your shell scripts and other files, rather
preprocessor. If this macro is used, warnings will be treated as fatal
errors instead for the current language. This macro is useful when the
results of configuration will be used where warnings are unacceptable; for
-instance, if parts of a program are built with the GCC @samp{-Werror}
-option. If the whole program will be built using @samp{-Werror} it is
-often simpler to put @samp{-Werror} in the compiler flags (@code{CFLAGS},
+instance, if parts of a program are built with the GCC @option{-Werror}
+option. If the whole program will be built using @option{-Werror} it is
+often simpler to put @option{-Werror} in the compiler flags (@code{CFLAGS},
etc.).
@end defmac
These primitives are really meant to make M4 more useful for specific
domains: they should be considered like command line options:
@option{--quotes}, @option{--comments}, @option{--words}, and
-@code{--syntax}. Nevertheless, they are implemented as M4 builtins, as
+@option{--syntax}. Nevertheless, they are implemented as M4 builtins, as
it makes M4 libraries self contained (no need for additional options).
There lies the problem@enddots{}
@asindex{MESSAGE_FD}
The file descriptor for @samp{checking for...} messages and results.
Normally this directs messages to the standard output, however when
-@command{configure} is run with the @code{-q} option, messages sent to
+@command{configure} is run with the @option{-q} option, messages sent to
@code{AS_MESSAGE_FD} will be discarded.
If you want to display some messages, consider using one of the printing
Avoid @samp{set -}, e.g., @samp{set - $my_list}. Posix no
longer requires support for this command, and in traditional shells
-@samp{set - $my_list} resets the @samp{-v} and @samp{-x} options, which
+@samp{set - $my_list} resets the @option{-v} and @option{-x} options, which
makes scripts harder to debug.
Some nonstandard shells do not recognize more than one option
@c ------------------
@prindex @command{chmod}
Avoid usages like @samp{chmod -w file}; use @samp{chmod a-w file}
-instead, for two reasons. First, plain @samp{-w} does not necessarily
+instead, for two reasons. First, plain @option{-w} does not necessarily
make the file unwritable, since it does not affect mode bits that
correspond to bits in the file mode creation mask. Second,
-Posix says that the @samp{-w} might be interpreted as an
+Posix says that the @option{-w} might be interpreted as an
implementation-specific option, not as a mode; Posix suggests
using @samp{chmod -- -w file} to avoid this confusion, but unfortunately
@samp{--} does not work on some older hosts.
Some traditional @command{grep} implementations do not work on long
input lines. Also, many implementations do not support multiple regexps
-with @option{-e}: they either reject @samp{-e} entirely (e.g., Solaris)
+with @option{-e}: they either reject @option{-e} entirely (e.g., Solaris)
or honor only the last pattern (e.g., @acronym{IRIX} 6.5). To
work around these problems, invoke @code{AC_PROG_GREP} and then use
@code{$GREP}.
-Another possible workaround for the multiple @samp{-e} problem is to
+Another possible workaround for the multiple @option{-e} problem is to
separate the patterns by newlines, for example:
@example
implementations and with Open@acronym{BSD} 3.8 @command{grep}.
Traditional @command{grep} implementations (e.g., Solaris) do not
-support the @option{-E} or @samp{-F} options. To work around these
+support the @option{-E} or @option{-F} options. To work around these
problems, invoke @code{AC_PROG_EGREP} and then use @code{$EGREP}, and
similarly for @code{AC_PROG_FGREP} and @code{$FGREP}.
In older versions of Mac OS X, @command{od} does not support the
standard Posix options @option{-A}, @option{-j}, @option{-N}, or
@option{-t}, or the @acronym{XSI} option @option{-s}. The only
-supported Posix option is @code{-v}, and the only supported
+supported Posix option is @option{-v}, and the only supported
@acronym{XSI} options are those in @option{-bcdox}. The BSD
@command{hexdump} program can be used instead.
@end example
You have a few possibilities if you do want the @code{foo=bar} override
-to propagate to sub-@command{make}s. One is to use the @code{-e}
+to propagate to sub-@command{make}s. One is to use the @option{-e}
option, which causes all environment variables to have precedence over
the @file{Makefile} macro definitions, and declare foo as an environment
variable:
% @kbd{env foo=bar make -e}
@end example
-The @code{-e} option is propagated to sub-@command{make}s automatically,
+The @option{-e} option is propagated to sub-@command{make}s automatically,
and since the environment is inherited between @command{make}
invocations, the @code{foo} macro will be overridden in
sub-@code{make}s as expected.
outside of a @file{Makefile}, for instance from a script or from the
command line. When run inside a @command{make} rule, @acronym{GNU}
@command{make} 3.80 and prior versions forget to propagate the
-@code{-e} option to sub-@command{make}s.
+@option{-e} option to sub-@command{make}s.
-Moreover, using @code{-e} could have unexpected side-effects if your
+Moreover, using @option{-e} could have unexpected side-effects if your
environment contains some other macros usually defined by the
Makefile. (See also the note about @code{make -e} and @code{SHELL}
below.)
If you mean to override the result of @command{config.guess}, use
@option{--build}, not @option{--host}, since the latter enables
cross-compilation. For historical reasons, passing @option{--host} also
-changes the build type. Therefore, whenever you specify @code{--host},
-be sure to specify @code{--build} too; this will be fixed in the
+changes the build type. Therefore, whenever you specify @option{--host},
+be sure to specify @option{--build} too; this will be fixed in the
future. So, to enter cross-compilation mode, use a command like this
@example
Hint: if you mean to override the result of @command{config.guess},
prefer @option{--build} over @option{--host}. In the future,
@option{--host} will not override the name of the build system type.
-Whenever you specify @code{--host}, be sure to specify @code{--build}
+Whenever you specify @option{--host}, be sure to specify @option{--build}
too.
@sp 1
enter cross-compilation mode. This is fragile. Moreover, by the time
the compiler test is performed, it may be too late to modify the
build-system type: other tests may have already been performed.
-Therefore, whenever you specify @code{--host}, be sure to specify
-@code{--build} too.
+Therefore, whenever you specify @option{--host}, be sure to specify
+@option{--build} too.
@example
./configure --build=i686-pc-linux-gnu --host=m68k-coff
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