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(libc.info)Argp Parsers

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Specifying Argp Parsers
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   The first argument to the `argp_parse' function is a pointer to a
`struct argp', which is known as an "argp parser":

 - Data Type: struct argp
     This structure specifies how to parse a given set of options and
     arguments, perhaps in conjunction with other argp parsers.  It has
     the following fields:

    `const struct argp_option *options'
          A pointer to a vector of `argp_option' structures specifying
          which options this argp parser understands; it may be zero if
          there are no options at all.  Note: Argp Option Vectors.

    `argp_parser_t parser'
          A pointer to a function that defines actions for this parser;
          it is called for each option parsed, and at other
          well-defined points in the parsing process.  A value of zero
          is the same as a pointer to a function that always returns
          `ARGP_ERR_UNKNOWN'.  Note: Argp Parser Functions.

    `const char *args_doc'
          If non-zero, a string describing what non-option arguments
          are called by this parser.  This is only used to print the
          `Usage:' message.  If it contains newlines, the strings
          separated by them are considered alternative usage patterns
          and printed on separate lines.  Lines after the first are
          prefixed by ` or: ' instead of `Usage:'.

    `const char *doc'
          If non-zero, a string containing extra text to be printed
          before and after the options in a long help message, with the
          two sections separated by a vertical tab (`'\v'', `'\013'')
          character.  By convention, the documentation before the
          options is just a short string explaining what the program
          does.  Documentation printed after the options describe
          behavior in more detail.

    `const struct argp_child *children'
          A pointer to a vector of `argp_children' structures.  This
          pointer specifies which additional argp parsers should be
          combined with this one.  Note: Argp Children.

    `char *(*help_filter)(int KEY, const char *TEXT, void *INPUT)'
          If non-zero, a pointer to a function that filters the output
          of help messages.  Note: Argp Help Filtering.

    `const char *argp_domain'
          If non-zero, the strings used in the argp library are
          translated using the domain described by this string.  If
          zero, the current default domain is used.


   Of the above group, `options', `parser', `args_doc', and the `doc'
fields are usually all that are needed.  If an argp parser is defined
as an initialized C variable, only the fields used need be specified in
the initializer.  The rest will default to zero due to the way C
structure initialization works.  This design is exploited in most argp
structures; the most-used fields are grouped near the beginning, the
unused fields left unspecified.

Options

Argp Option Vectors. Specifying options in an argp parser.

Argp Parser Functions

Defining actions for an argp parser.

Children

Argp Children. Combining multiple argp parsers.

Help Filtering

Argp Help Filtering. Customizing help output for an argp parser.