25.3.8.1 Special Keys for Argp Help Filter Functions

The following special values may be passed to an argp help filter function as the first argument in addition to key values for user options. They specify which help text the text argument contains:

ARGP_KEY_HELP_PRE_DOC

The help text preceding options.

ARGP_KEY_HELP_POST_DOC

The help text following options.

ARGP_KEY_HELP_HEADER

The option header string.

ARGP_KEY_HELP_EXTRA

This is used after all other documentation; text is zero for this key.

ARGP_KEY_HELP_DUP_ARGS_NOTE

The explanatory note printed when duplicate option arguments have been suppressed.

ARGP_KEY_HELP_ARGS_DOC

The argument doc string; formally the args_doc field from the argp parser. See Argp Parsers.