Normally programs using argp need not be written with particular
printing argument-usage-type help messages in mind as the standard
‘--help’ option is handled automatically by argp. Typical error
cases can be handled using
argp_error. See Functions For Use in Argp Parsers. However, if it’s
desirable to print a help message in some context other than parsing the
program options, argp offers the
Preliminary: | MT-Unsafe race:argpbuf env locale | AS-Unsafe heap i18n corrupt | AC-Unsafe mem corrupt lock | See POSIX Safety Concepts.
This outputs a help message for the argp parser argp to stream. The type of messages printed will be determined by flags.
Any options such as ‘--help’ that are implemented automatically by
argp itself will not be present in the help output; for this
reason it is best to use
argp_state_help if calling from within
an argp parser function. See Functions For Use in Argp Parsers.