getopt(3)                           CLIX                           getopt(3)



  NAME

    getopt - Gets an option letter from argument vector

  LIBRARY

    Standard C Library (libc.a)

  SYNOPSIS

    int getopt(
      int argc ,
      char **argv ,
      char *optstring );

    extern char *optarg ;
    extern int optind ;
    extern int opterr ;

  PARAMETERS

    argc        The number of command line arguments.

    argv        A pointer to a pointer to a character string.

    optstring   A pointer to a character string representing command options.

  DESCRIPTION

    The getopt() function returns the next option letter in argv that matches
    a letter in optstring.  It supports all the rules of the command syntax
    standard (see intro).  So that all new commands adhere to the command
    syntax standard, they should use getopts or getopt() to parse positional
    parameters and check for options that are legal for that command.

    The optstring parameter must contain the option letters the command using
    getopt() recognizes.  If a letter is followed by a colon, the option is
    expected to have an argument or group of arguments which must be separated
    from it by white space.

    The optarg variable is set to point to the start of the option-argument on
    return from getopt().

    The getopt() function places in the optind variable the argv index of the
    next argument to be processed.  The optind variable is external and is
    initialized to 1 before the first call to getopt().

  EXAMPLES

    The following code fragment shows how one might process the arguments for
    a command that can take the mutually exclusive options a and b, and the



  2/94 - Intergraph Corporation                                              1

  getopt(3)                           CLIX                           getopt(3)



    option o, which requires an option-argument:

    main (argc, argv)
    int argc;
    char **argv;
    {
         int c;
         extern char *optarg;
         extern int optind;
         .
         .
         .
         while ((c = getopt(argc, argv, "abo:")) != -1)
              switch (c) {
              case 'a':
                   if (bflg)
                        errflg++;
                   else
                        aflg++;
                   break;
              case 'b':
                   if (aflg)
                        errflg++;
                   else
                        bproc();
                   break;
              case 'o':
                   ofile = optarg;
                   break;
              case '?':
                   errflg++;
              }
         if (errflg) {
              (void)fprintf(stderr, "usage: ... ");
              exit (2);
         }
         for ( ; optind < argc; optind++) {
              if (access(argv[optind], 4)) {
         .
         .
         .
    }


  CAUTIONS

    Although the following command, syntax rule (see intro) relaxations are
    permitted under the current implementation, they should not be used since
    they may not be supported in future releases of the system.  As in the
    EXAMPLES section, a and b are options, and the option o requires an
    option-argument:



  2                                              Intergraph Corporation - 2/94

  getopt(3)                           CLIX                           getopt(3)



    cmd -aboxxx file
           Rule 5 violation:  options with option-arguments must not be
           grouped with other options.

    cmd -ab -oxxx file
           Rule 6 violation:  there must be white space after an option that
           takes an option-argument.

    Changing the value of the variable optind or calling getopt() with
    different values of argv can lead to unexpected results.

  RETURN VALUES

    When all options are processed (up to the first nonoption argument),
    getopt() returns -1.  The special -- option may be used to delimit the end
    of the options.  When -- is encountered, -1 is returned, and -- is
    skipped.

  ERRORS

    The getopt() function displays an error message on stderr and returns a
    question mark (?) when it encounters an option letter not included in
    optstring or no option-argument after an option that expects one.  This
    error message is disabled by setting opterr to 0.

  RELATED INFORMATION

    Commands:  getopt(1), intro(1)


























  2/94 - Intergraph Corporation                                              3