getopt(3C)           COMPATIBILITY FUNCTIONS           getopt(3C)



NAME
     getopt - get option letter from argument vector

SYNOPSIS
     #include <stdlib.h>

     int getopt (int argc, char * const *argv, const  char  *opt-
     string);

     extern char *optarg;

     extern int optind, opterr, optopt;

DESCRIPTION
     getopt returns the next option letter in argv that matches a
     letter  in optstring.  It supports all the rules of the com-
     mand syntax standard [see intro(1)].  Since all new commands
     are  intended to adhere to the command syntax standard, they
     should use  getopts(1),  getopt(3C),  or  getsubopts(3C)  to
     parse  positional  parameters and check for options that are
     legal for that command.

     optstring must contain the option letters the command  using
     getopt  will  recognize; if a letter is followed by a colon,
     the option is expected to have  an  argument,  or  group  of
     arguments,  which  may  be separated from it by white space.
     optarg is set to point to the start of the  option  argument
     on return from getopt.

     getopt places in optind the argv index of the next  argument
     to be processed.  optind is external and is initialized to 1
     before the first call to getopt.  When all options have been
     processed  (i.e.,  up  to  the  first  non-option argument),
     getopt returns EOF.  The special option ``--'' (two hyphens)
     may  be  used  to delimit the end of the options; when it is
     encountered, EOF is returned and ``--'' is skipped. This  is
     useful  in  delimiting  non-option arguments that begin with
     ``-'' (hyphen).

EXAMPLE
     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 option o, which requires  an  argu-
     ment:

     #include <stdlib.h>
     #include <stdio.h>

     main (int argc, char **argv)
     {
          int c;
          extern char *optarg;



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getopt(3C)           COMPATIBILITY FUNCTIONS           getopt(3C)



          extern int optind;
          int aflg = 0;
          int bflg = 0;
          int errflg = 0;
          char *ofile = NULL;

          while ((c = getopt(argc, argv, "abo:")) != EOF)
               switch (c) {
               case 'a':
                    if (bflg)
                         errflg++;
                    else
                         aflg++;
                    break;
               case 'b':
                    if (aflg)
                         errflg++;
                    else
                         bflg++;
                    break;
               case 'o':
                    ofile = optarg;
                    (void)printf("ofile = %s\n", ofile);
                    break;
               case '?':
                    errflg++;
               }
          if (errflg) {
               (void)fprintf(stderr,
                    "usage: cmd [-a|-b] [-o<file>] files...\n");
               exit (2);
          }
          for ( ; optind < argc; optind++)
               (void)printf("%s\n", argv[optind]);
          return 0;
     }

SEE ALSO
     getsubopt(3C).
     getopts(1), intro(1) in the User's Reference Manual.

DIAGNOSTICS
     getopt prints an error message on  the  standard  error  and
     returns  a  ``?''   (question  mark)  when  it encounters an
     option letter not included in optstring or no argument after
     an  option that expects one.  This error message may be dis-
     abled by setting opterr to 0.  The value  of  the  character
     that caused the error is in optopt.

NOTES
     The library routine getopt does not fully check  for  manda-
     tory arguments.  That is, given an option string a:b and the



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getopt(3C)           COMPATIBILITY FUNCTIONS           getopt(3C)



     input -a -b, getopt assumes that -b is the  mandatory  argu-
     ment to the option -a and not that -a is missing a mandatory
     argument.  It is a violation of the command syntax  standard
     [see intro(1)] for options with arguments to be grouped with
     other options, as in cmd -aboxxx file, where  a  and  b  are
     options,  o  is an option that requires an argument, and xxx
     is the argument to o.  Although this syntax is permitted  in
     the current implementation, it should not be used because it
     may not be supported in future releases. The correct  syntax
     is cmd -ab -oxxx file.













































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