GETOPT(3)						     Library Functions Manual							 GETOPT(3)

NAME

       getopt - get option letter from argv

SYNOPSIS

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

       extern char *optarg;
       extern int optind;

DESCRIPTION

       Getopt returns the next option letter in argv that matches a letter in optstring.  Optstring is a string of recognized option letters; if a
       letter is followed by a colon, the option is expected to have an argument that may or may not 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.  Because optind is external, it is normally initialized to
       zero automatically 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 -- may be used to
       delimit the end of the options; EOF will be returned, and -- will be skipped.

DIAGNOSTICS

       Getopt prints an error message on stderr and returns a question mark (?)  when it encounters an option letter not included in optstring.

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 options f and o, both of which require arguments:

	      main(argc, argv)
	      int argc;
	      char **argv;
	      {
		   int c;
		   extern int optind;
		   extern char *optarg;
		   .
		   .
		   .
		   while ((c = getopt(argc, argv, "abf:o:")) != EOF)
			switch (c) {
			case `a':
			     if (bflg)
				  errflg++;
			     else
				  aflg++;
			     break;
			case `b':
			     if (aflg)
				  errflg++;
			     else
				  bproc();
			     break;
			case `f':
			     ifile = optarg;
			     break;
			case `o':
			     ofile = optarg;
			     break;
			case `?':
			default:
			     errflg++;
			     break;
			}
		   if (errflg) {
			fprintf(stderr, "Usage: ...");
			exit(2);
		   }
		   for (; optind < argc; optind++) {
			.
			.
			.
		   }
		   .
		   .
		   .
	      }

HISTORY

       Written by Henry Spencer, working from a Bell Labs manual page.	Modified by Keith Bostic to behave more like the System V version.

BUGS

       It is not obvious how `-' standing alone should be treated;  this version treats it as a non-option argument, which is not always right.

       Option arguments are allowed to begin with `-'; this is reasonable but reduces the amount of error checking possible.

       Getopt is quite flexible but the obvious price must be paid:  there is much it could do that it doesn't, like checking  mutually  exclusive
       options, checking type of option arguments, etc.

4.3 Berkeley Distribution					   May 27, 1986 							 GETOPT(3)