Argp Help Flags (The GNU C Library)

#### 26.3.10 Flags for the `argp_help` Function ¶

When calling `argp_help` (see The `argp_help` Function) or `argp_state_help` (see Functions For Use in Argp Parsers) the exact output is determined by the flags argument. This should consist of any of the following flags, or’d together:

`ARGP_HELP_USAGE` ¶

  A unix ‘`Usage:`’ message that explicitly lists all options.

`ARGP_HELP_SHORT_USAGE` ¶

  A unix ‘`Usage:`’ message that displays an appropriate placeholder to indicate where the options go; useful for showing the non-option argument syntax.

`ARGP_HELP_SEE` ¶

  A ‘`Try … for more help`’ message; ‘`…`’ contains the program name and ‘`--help`’.

`ARGP_HELP_LONG` ¶

  A verbose option help message that gives each option available along with its documentation string.

`ARGP_HELP_PRE_DOC` ¶

  The part of the argp parser doc string preceding the verbose option help.

`ARGP_HELP_POST_DOC` ¶

  The part of the argp parser doc string that following the verbose option help.

`ARGP_HELP_DOC` ¶

  `(ARGP_HELP_PRE_DOC | ARGP_HELP_POST_DOC)`

`ARGP_HELP_BUG_ADDR` ¶

  A message that prints where to report bugs for this program, if the `argp_program_bug_address` variable contains this information.

`ARGP_HELP_LONG_ONLY` ¶

  This will modify any output to reflect the `ARGP_LONG_ONLY` mode.

The following flags are only understood when used with `argp_state_help`. They control whether the function returns after printing its output, or terminates the program:

`ARGP_HELP_EXIT_ERR` ¶

  This will terminate the program with `exit (argp_err_exit_status)`.

`ARGP_HELP_EXIT_OK` ¶

  This will terminate the program with `exit (0)`.

The following flags are combinations of the basic flags for printing standard messages:

`ARGP_HELP_STD_ERR` ¶

  Assuming that an error message for a parsing error has printed, this prints a message on how to get help, and terminates the program with an error.

`ARGP_HELP_STD_USAGE` ¶

  This prints a standard usage message and terminates the program with an error. This is used when no other specific error messages are appropriate or available.

`ARGP_HELP_STD_HELP` ¶

  This prints the standard response for a ‘`--help`’ option, and terminates the program successfully.