getopt(3C)																getopt(3C)

NAME

       getopt(), optarg, opterr, optind, optopt - get option letter from argument vector

SYNOPSIS


DESCRIPTION

       returns	the  next option letter in argv (starting from that matches a letter in optstring.  argc and argv are the argument count and argu-
       ment array as passed to optstring is a string of recognized option characters; if a character is followed by a colon, the option  takes	an
       argument which may or may not be separated from it by whitespace.

       is the index of the next element of the vector to be processed.	It is initialized to 1 by the system, and updates it when it finishes with
       each element of

       returns the next option character from argv that matches a character in optstring, if there is one that matches.  If the  option  takes	an
       argument, sets the variable to point to the option argument as follows:

	 o  If	the  option  was the last character in the string pointed to by an element of argv, then contains the next element of argv, and is
	    incremented by 2.  If the resulting value of is greater than or equal to argc, this indicates a missing option argument,  and  returns
	    an error indication.

	 o  Otherwise, points to the string following the option character in that element of argv, and is incremented by 1.

       If, when is called, is NULL, or the string pointed to by either does not begin with the character or consists only of the character returns
       -1 without changing If points to the string returns -1 after incrementing

       If encounters an option character that is not contained in optstring, it returns the question-mark character.   If  it  detects	a  missing
       option  argument,  it  returns the colon character if the first character of optstring was a colon, or a question-mark character otherwise.
       In either case, sets the variable to the option character that caused the error.  If the application has not set the variable to  zero  and
       the first character of optstring is not a colon, also prints a diagnostic message to standard error.

       The special option can be used to delimit the end of the options; -1 is returned, and is skipped.

RETURN VALUE

       returns the next option character specified on the command line.  A colon is returned if detects a missing argument and the first character
       of optstring was a colon

       A question-mark is returned if encounters an option character not in optstring or detects a missing argument and  the  first  character	of
       optstring was not a colon

       Otherwise, returns -1 when all command line options have been parsed.

EXTERNAL INFLUENCES

   Locale
       The category determines the interpretation of option letters as single and/or multi-byte characters.

   International Code Set Support
       Single- and multibyte character code sets are supported.

ERRORS

       fails under the following conditions:

       [EILSEQ]       An invalid multibyte character sequence was encountered during option processing.

EXAMPLES

       The  following  code fragment shows to process arguments for a command that can take the mutually exclusive options and and the options and
       both of which require arguments:

	      #include <stdio.h>
	      #include <unistd.h>
	      main (int argc, char *argv[])
	      {
		  int c;
		  int bflg, aflg, errflg;
		  extern char *optarg;
		  extern int optind, optopt;
		  .
		  .
		  .
		  while ((c = getopt(argc, argv, ":abf:o:")) != -1)
		      switch (c) {
		      case 'a':
			  if (bflg)
			      errflg++;
			  else
			      aflg++;
			  break;
		      case 'b':
			  if (aflg)
			      errflg++;
			  else {
			      bflg++;
			      bproc( );
			  }
			  break;
		      case 'f':
			  ifile = optarg;
			  break;
		      case 'o':
			  ofile = optarg;
			  break;
		      case ':':        /* -f or -o without arguments */
			  fprintf(stderr, "Option -%c requires an argument
",
			      optopt);
			  errflg++;
			  break;
		      case '?':
			  fprintf(stderr, "Unrecognized option: - %c
",
			      optopt);
			  errflg++;
		      }
		  if (errflg) {
		      fprintf(stderr, "usage: . . . ");
		      exit(2);
		  }
		  for ( ; optind < argc; optind++) {
		      if (access(argv[optind], 4)) {
		  .
		  .
		  .
	      }

WARNINGS

       Options can be any ASCII characters except colon question mark or null

SEE ALSO

       getopt(1), thread_safety(5).

STANDARDS CONFORMANCE

																	getopt(3C)