On GNU/Linux terminal, when I add --help to commands from GNU packages, I get a help text that is formatted in a very consistent way. These help texts list the options accepted by that command with this format:
option characters, long options ............ [aligned] explanation of the option
For example, this is a part of the help text of the man command:
Usage: man [OPTION...] [SECTION] PAGE...
-C, --config-file=FILE use this user configuration file
-d, --debug emit debugging messages
-D, --default reset all options to their default values
--warnings[=WARNINGS] enable warnings from groff
Main modes of operation:
-f, --whatis equivalent to whatis
-k, --apropos equivalent to apropos
-K, --global-apropos search for text in all pages
-l, --local-file interpret PAGE argument(s) as local filename(s)
-w, --where, --path, --location
print physical location of man page(s)
-W, --where-cat, --location-cat
print physical location of cat file(s)
I was wondering if there was a standard way (possibly used by GNU packages) to print with the same format, without having to deal with tab stops etc. I have found getopt from POSIX API to parse these options, but I can't find a way to print a list of them.
The GNU tools use argp, which is part of the GNU C library. It offers more options than getopt, including help.
See: https://www.gnu.org/software/libc/manual/html_node/Argp.html