Up: Argp Help

#### 25.3.10 Flags for the `argp_help` Function

When calling `argp_help` (see Argp Help) or `argp_state_help` (see Argp Helper Functions) 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.