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Update doc for POSIX, OS versions

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* doc/autoconf.texi: Some updates for newer POSIX and OS versions.
Omit no-longer-relevant version numbers.
This commit is contained in:
Paul Eggert 2025-01-19 10:14:31 -08:00
parent 632282145b
commit cbb9e1e834
1 changed files with 37 additions and 38 deletions
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@ -4891,7 +4891,7 @@ be used. @xref{Gnulib}.
@c @fuindex strerror_r
@prindex @code{strerror_r}
POSIX specifies that @code{strerror_r} returns an @code{int}, but many
systems (e.g., GNU C Library version 2.36) provide a
systems (e.g., the GNU C Library) provide a
different version returning a @code{char *}. @code{AC_FUNC_STRERROR_R}
can detect which is in use (@pxref{Particular Functions}).
@ -5325,7 +5325,7 @@ The result of this macro is cached in the @code{ac_cv_func_getpgrp_void}
variable.
This macro is obsolescent, as current systems have a @code{getpgrp}
whose signature conforms to POSIX. New programs need not use this macro.
whose signature conforms to POSIX@. New programs need not use this macro.
@end defmac
@defmac AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK
@ -5521,7 +5521,7 @@ to @samp{int}, @code{SELECT_TYPE_ARG234} defaults to @samp{int *},
and @code{SELECT_TYPE_ARG5} defaults to @samp{struct timeval *}.
This macro is obsolescent, as current systems have a @code{select} whose
signature conforms to POSIX. New programs need not use this macro.
signature conforms to POSIX@. New programs need not use this macro.
@end defmac
@defmac AC_FUNC_SETPGRP
@ -5604,7 +5604,7 @@ it is declared, define @code{HAVE_DECL_STRERROR_R}. If it returns a
@code{char *} message, define @code{STRERROR_R_CHAR_P}; otherwise it
returns an @code{int} error number. The Thread-Safe Functions option of
POSIX requires @code{strerror_r} to return @code{int}, but
many systems (including, for example, version 2.2.4 of the GNU C
many systems (including, for example, the GNU C
Library) return a @code{char *} value that is not necessarily equal to
the buffer argument.
@ -6263,7 +6263,7 @@ example:
This macro caches its result in the @code{ac_cv_header_sys_wait_h}
variable.
This macro is obsolescent, as current systems are compatible with POSIX.
This macro is obsolescent, as current systems are compatible with POSIX@.
New programs need not use this macro.
@end defmac
@ -6274,7 +6274,7 @@ POSIX systems. If there is no @file{unistd.h}, it is definitely
not a POSIX system. However, some non-POSIX systems do
have @file{unistd.h}.
The way to check whether the system supports POSIX is:
The way to check whether the system says it supports POSIX is:
@example
@group
@ -11986,12 +11986,12 @@ Like the M4 builtins, but warn against multiple inclusions of @var{file}.
@defmacx m4_maketemp (@var{template})
@msindex{maketemp}
@msindex{mkstemp}
POSIX requires @code{maketemp} to replace the trailing @samp{X}
Older versions of POSIX specified a macro @code{maketemp},
which replaced the trailing @samp{X}
characters in @var{template} with the process id, without regards to the
existence of a file by that name, but this a security hole. When this
was pointed out to the POSIX folks, they agreed to invent a new macro
@code{mkstemp} that always creates a uniquely named file, but not all
versions of GNU M4 support the new macro. In M4sugar,
existence of a file by that name.
This was a security hole, so current POSIX instead specifies a macro
@code{mkstemp} that always creates a uniquely named file. In M4sugar,
@code{m4_maketemp} and @code{m4_mkstemp} are synonyms for each other,
and both have the secure semantics regardless of which macro the
underlying M4 provides.
@ -15463,14 +15463,14 @@ that expects case-sensitive filenames, it is best to create a separate
disk volume or disk image formatted as case sensitive; this can be done
using the @command{diskutil} command or the Disk Utility application.
@item QNX 4.25
@cindex QNX 4.25
@item QNX
@cindex QNX
@c FIXME: Please, if you feel like writing something more precise,
@c it'd be great. In particular, I can't understand the difference with
@c QNX Neutrino.
QNX is a realtime operating system running on Intel architecture
meant to be scalable from the small embedded systems to the hundred
processor super-computer. It claims to be POSIX certified. More
processor super-computer. More
information is available on the
@uref{https://@/blackberry.qnx.com/@/en, QNX home page}.
@ -15562,7 +15562,7 @@ you'll need to use Bash 2.05 for all other build tasks as well.
@prindex @samp{ksh88}
@prindex @samp{ksh93}
The Korn shell is compatible with the Bourne family and it mostly
conforms to POSIX. It has two major variants commonly
conforms to POSIX@. It has two major variants commonly
called @samp{ksh88} and @samp{ksh93}, named after the years of initial
release. It is usually called @command{ksh}, but is called @command{sh}
on some hosts if you set your path appropriately.
@ -15589,7 +15589,7 @@ available: it has most of the @samp{ksh88} features along with a few of
its own. It usually sets @code{KSH_VERSION}, except if invoked as
@command{/bin/sh} on OpenBSD, and similarly to Bash you can require
POSIX compatibility by running @samp{set -o posix}. Unfortunately, with
@command{pdksh} 5.2.14 (the latest stable version as of January 2007)
@command{pdksh} 5.2.14 (the latest stable version as of 2025)
POSIX mode is buggy and causes @command{pdksh} to depart from POSIX in
at least one respect, see @ref{Shell Substitutions}.
@ -15779,7 +15779,7 @@ One workaround is to grep out uninteresting lines, hoping not to remove
good ones.
If you intend to redirect both standard error and standard output,
redirect standard output first. This works better with HP-UX,
redirect standard output first. This works better with AIX,
since its shell mishandles tracing if standard error is redirected
first:
@ -15865,13 +15865,13 @@ y1
@noindent
As a workaround, @command{echo} or @command{eval} can be used.
Don't rely on file descriptors 0, 1, and 2 remaining closed in a
When running a subsidiary program be careful if descriptor 0 is not open
for reading or decriptors 1 and 2 are not open for writing,
as the subsidiary program might not behave as expected.
In particular, don't rely on file descriptors 0, 1, and 2 remaining closed in a
subsidiary program. If any of these descriptors is closed, the
operating system may open an unspecified file for the descriptor in the
new process image. POSIX 2008 says this may be done only if the
subsidiary program is set-user-ID or set-group-ID, but HP-UX 11.23 does
it even for ordinary programs, and the next version of POSIX will allow
HP-UX behavior.
newly created process.
If you want a file descriptor above 2 to be inherited into a child
process, then you must use redirections specific to that command or a
@ -17016,7 +17016,7 @@ the last command executed.
When this variable is set it specifies a list of directories to search
when invoking @code{cd} with a relative file name that did not start
with @samp{./} or @samp{../}. POSIX
1003.1-2001 says that if a nonempty directory name from @env{CDPATH}
says that if a nonempty directory name from @env{CDPATH}
is used successfully, @code{cd} prints the resulting absolute
file name. Unfortunately this output can break idioms like
@samp{abs=`cd src && pwd`} because @code{abs} receives the name twice.
@ -17351,7 +17351,7 @@ Conventions}, for more information about @code{PATH_SEPARATOR}.
@item POSIXLY_CORRECT
@evindex POSIXLY_CORRECT
In the GNU environment, exporting @env{POSIXLY_CORRECT} with any value
(even empty) causes programs to try harder to conform to POSIX.
(even empty) causes programs to try harder to conform to POSIX@.
Autoconf does not directly manipulate this variable, but @command{bash}
ties the shell variable @env{POSIXLY_CORRECT} to whether the script is
running in POSIX mode. Therefore, take care when exporting or unsetting
@ -17368,9 +17368,9 @@ posix off
@item PWD
@evindex PWD
POSIX 1003.1-2001 requires that @command{cd} and
@command{pwd} must update the @env{PWD} environment variable to point
to the logical name of the current directory, but traditional shells
POSIX requires that @command{cd}
must update the @env{PWD} environment variable to point
to the name of the current directory, but traditional shells
do not support this. This can cause confusion if one shell instance
maintains @env{PWD} but a subsidiary and different shell does not know
about @env{PWD} and executes @command{cd}; in this case @env{PWD}
@ -17797,7 +17797,7 @@ $ @kbd{/bin/sh -c 'case `false` in ?) ;; esac; echo $?'}
@item @command{cd}
@c ---------------
@prindex @command{cd}
POSIX 1003.1-2001 requires that @command{cd} must support
POSIX requires that @command{cd} must support
the @option{-L} (``logical'') and @option{-P} (``physical'') options,
with @option{-L} being the default. However, traditional shells do
not support these options, and their @command{cd} command has the
@ -18268,7 +18268,7 @@ directory name, some of whose components may be symbolic links. These
directory names are in contrast to ``physical'' directory names, whose
components are all directories.
POSIX 1003.1-2001 requires that @command{pwd} must support
POSIX requires that @command{pwd} must support
the @option{-L} (``logical'') and @option{-P} (``physical'') options,
with @option{-L} being the default. However, traditional shells do
not support these options, and their @command{pwd} command has the
@ -18539,7 +18539,7 @@ lacks it.
To test for symbolic links on systems that have them, use
@samp{test -h} rather than @samp{test -L}; either form conforms to
POSIX 1003.1-2001, but @option{-h} has been around longer.
POSIX, but @option{-h} has been around longer.
The commands @samp{test A -ot B} and @samp{test A -nt B} are not reliable
on macOS @command{sh} through at least macOS Sequoia 15.1.1 (2024),
@ -18902,7 +18902,7 @@ length of regular expressions and literal strings in an Awk program.
Traditional Awk implementations derived from Unix version 7, such as
Solaris @command{/bin/awk}, have many limitations and do not
conform to POSIX. Nowadays @code{AC_PROG_AWK} (@pxref{Particular
conform to POSIX@. Nowadays @code{AC_PROG_AWK} (@pxref{Particular
Programs}) finds you an Awk that doesn't have these problems, but if
for some reason you prefer not to use @code{AC_PROG_AWK} you may need to
address them. For more detailed descriptions, see @ref{Language
@ -19024,9 +19024,9 @@ The default executable, produced by @samp{cc foo.c}, can be
@end itemize
The C compiler's traditional name is @command{cc}, but other names like
@command{gcc} are common. POSIX 1003.1-2001 through 1003.1-2017 specify the
name @command{c99}, but older POSIX editions specified
@command{c89}, future POSIX standards will likely specify
@command{gcc} are common. POSIX 1003.1-2024 specifies the
name @command{c17}, but older POSIX editions specified
@command{c99} or @command{c89}, future POSIX standards will likely specify
other commands, and anyway these standard names are rarely used in
practice. Typically the C compiler is invoked from makefiles that use
@samp{$(CC)}, so the value of the @samp{CC} make variable selects the
@ -19345,12 +19345,12 @@ POSIX spec for @command{find}} for @command{find} operands that
should be portable nowadays.
The replacement of @samp{@{@}} is guaranteed only if the argument is
exactly @emph{@{@}}, not if it's only a part of an argument. For
instance, on HP-UX 11:
exactly @samp{@{@}}, not if @samp{@{@}} only a part of a larger argument.
For instance, on AIX 7.3:
@example
$ @kbd{touch foo}
$ @kbd{find . -name foo -exec echo "@{@}-@{@}" \;}
$ @kbd{find . -name foo -exec echo '@{@}-@{@}' \;}
@{@}-@{@}
@end example
@ -19358,7 +19358,6 @@ $ @kbd{find . -name foo -exec echo "@{@}-@{@}" \;}
while GNU @command{find} reports @samp{./foo-./foo}.
POSIX allows either behavior.
@anchor{grep}
@item @command{grep}
@c -----------------