This structure specifies a single option that an argp parser
understands, and how to parse and document it. It has the following fields:
const char *name
- The long name for this option, corresponding to the long option
--name ; this field can be zero if this option only has a
short name. To specify multiple names for an option, additional entries
may follow this one, with the OPTION_ALIAS flag set (see Argp
Option Flags).
int key
- The integer key that is provided to the argp parser's parsing function
when this option is being parsed. Also, if key has a value that
is a printable ASCII character (i.e.,
isascii (key) is
true), it also specifies a short option -char , where
char is the ASCII character with the code key.
const char *arg
- If non-zero, this is the name of an argument associated with this
option, which must be provided (e.g., with the
--name=value or -char value
syntaxes) unless the OPTION_ARG_OPTIONAL flag (see Argp Option
Flags) is set, in which case it may be provided.
int flags
- Flags associated with this option (some of which are referred to above).
See Argp Option Flags.
const char *doc
- A documentation string for this option, for printing in help messages.
If both the
name and key fields are zero, this string
will be printed out-dented from the normal option column, making it
useful as a group header (it will be the first thing printed in its
group); in this usage, it's conventional to end the string with a
: character.
int group
- The group this option is in.
In a long help message, options are sorted alphabetically within each
group, and the groups presented in the order 0, 1, 2, ..., n,
-m, ..., -2, -1. Every entry in an
options array with this
field 0 will inherit the group number of the previous entry, or zero if
it's the first one, unless its a group header (
name and
key fields both zero), in which case, the previous entry + 1 is
the default. Automagic options such as --help are put into group
-1.
Note that because of C structure initialization rules, this field
often need not be specified, because 0 is the right value.
|