@node getopt_long_only
@subsection @code{getopt_long_only}
@findex getopt_long_only

LSB specification:@* @url{https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/baselib-getopt-long-only-3.html}

Documentation:
@itemize
@item
@ifinfo
@ref{Getopt Long Options,,Parsing Long Options with getopt_long,libc},
@end ifinfo
@ifnotinfo
@url{https://www.gnu.org/software/libc/manual/html_node/Getopt-Long-Options.html},
@end ifnotinfo
@item
@uref{https://www.kernel.org/doc/man-pages/online/pages/man3/getopt_long_only.3.html,,man getopt_long_only}.
@end itemize

Gnulib module: getopt-gnu

Portability problems fixed by Gnulib:
@itemize
@item
The function @code{getopt_long_only} does not obey the combination of
@samp{+} and @samp{:} flags in the options string on some platforms:
glibc 2.11.
@item
The use of @samp{W;} in the optstring argument to does not always
allow @code{-W foo} to behave synonymously with @code{--foo}:
glibc 2.11.
@item
The function @code{getopt_long_only} does not support the @samp{+}
flag in the options string on some platforms:
macOS 11.1, AIX 5.2, Solaris 10.
@item
The value of @code{optind} after a missing required argument is wrong
on some platforms:
macOS 11.1.
@item
The function @code{getopt_long_only} does not obey the @samp{-} flag
in the options string when @env{POSIXLY_CORRECT} is set on some platforms:
Cygwin 1.7.0.
@item
Some implementations fail to reset state, including re-checking
@env{POSIXLY_CORRECT}, when @code{optind} is set to @samp{0}:
NetBSD, Cygwin 1.7.0.
@item
The function @code{getopt_long_only} does not support options with
optional arguments on some platforms:
macOS 11.1, OpenBSD 4.0, AIX 5.2, Solaris 11 2010-11, Cygwin 1.5.x.
@item
This function is missing on some platforms:
FreeBSD 5.2.1, NetBSD 9.0, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, mingw, MSVC 14.
@item
This function crashes if the option string includes @code{W;} but
there are no long options, on some platforms:
glibc 2.14.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@item
Some implementations return success instead of reporting an ambiguity
if user's option is a prefix of two long options with the same outcome:
FreeBSD.
@item
The GNU Coding Standards discourage the use of @code{getopt_long_only}
in new programs.
@end itemize