GETOPT_LONG(3)						   BSD Library Functions Manual 					    GETOPT_LONG(3)

NAME

     getopt_long, getopt_long_only -- get long options from command line argument list

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <getopt.h>

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

     int
     getopt_long(int argc, char * const *argv, const char *optstring, const struct option *longopts, int *longindex);

     int
     getopt_long_only(int argc, char * const *argv, const char *optstring, const struct option *longopts, int *longindex);

DESCRIPTION

     The getopt_long() function is similar to getopt(3) but it accepts options in two forms: words and characters.  The getopt_long() function
     provides a superset of the functionality of getopt(3).  The getopt_long() function can be used in two ways.  In the first way, every long
     option understood by the program has a corresponding short option, and the option structure is only used to translate from long options to
     short options.  When used in this fashion, getopt_long() behaves identically to getopt(3).  This is a good way to add long option processing
     to an existing program with the minimum of rewriting.

     In the second mechanism, a long option sets a flag in the option structure passed, or will store a pointer to the command line argument in
     the option structure passed to it for options that take arguments.  Additionally, the long option's argument may be specified as a single
     argument with an equal sign, e.g.,

	   myprogram --myoption=somevalue

     When a long option is processed, the call to getopt_long() will return 0.	For this reason, long option processing without shortcuts is not
     backwards compatible with getopt(3).

     It is possible to combine these methods, providing for long options processing with short option equivalents for some options.  Less fre-
     quently used options would be processed as long options only.

     The getopt_long() call requires a structure to be initialized describing the long options.  The structure is:

	   struct option {
		   char *name;
		   int has_arg;
		   int *flag;
		   int val;
	   };

     The name field should contain the option name without the leading double dash.

     The has_arg field should be one of:

	   no_argument	      no argument to the option is expect
	   required_argument  an argument to the option is required
	   optional_argument  an argument to the option may be presented.

     If flag is not NULL, then the integer pointed to by it will be set to the value in the val field.	If the flag field is NULL, then the val
     field will be returned.  Setting flag to NULL and setting val to the corresponding short option will make this function act just like
     getopt(3).

     If the longindex field is not NULL, then the integer pointed to by it will be set to the index of the long option relative to longopts.

     The last element of the longopts array has to be filled with zeroes.

     The getopt_long_only() function behaves identically to getopt_long() with the exception that long options may start with '-' in addition to
     '--'.  If an option starting with '-' does not match a long option but does match a single-character option, the single-character option is
     returned.

RETURN VALUES

     If the flag field in struct option is NULL, getopt_long() and getopt_long_only() return the value specified in the val field, which is usu-
     ally just the corresponding short option.	If flag is not NULL, these functions return 0 and store val in the location pointed to by flag.
     These functions return ':' if there was a missing option argument, '?' if the user specified an unknown or ambiguous option, and -1 when the
     argument list has been exhausted.

ENVIRONMENT

     POSIXLY_CORRECT  If set, option processing stops when the first non-option is found and a leading '-' or '+' in the optstring is ignored.

EXAMPLES

     int bflag, ch, fd;
     int daggerset;

     /* options descriptor */
     static struct option longopts[] = {
	     { "buffy",      no_argument,	     NULL,	     'b' },
	     { "fluoride",   required_argument,      NULL,	     'f' },
	     { "daggerset",  no_argument,	     &daggerset,     1 },
	     { NULL,	     0, 		     NULL,	     0 }
     };

     bflag = 0;
     while ((ch = getopt_long(argc, argv, "bf:", longopts, NULL)) != -1)
	     switch (ch) {
	     case 'b':
		     bflag = 1;
		     break;
	     case 'f':
		     if ((fd = open(optarg, O_RDONLY, 0)) == -1)
			     err(1, "unable to open %s", optarg);
		     break;
	     case 0:
		     if (daggerset) {
			     fprintf(stderr,"Buffy will use her dagger to "
				 "apply fluoride to dracula's teeth
");
		     }
		     break;
	     default:
		     usage();
     }
     argc -= optind;
     argv += optind;

IMPLEMENTATION DIFFERENCES

     This section describes differences to the GNU implementation found in glibc-2.1.3:

     o	 Setting of optopt for long options with flag != NULL:

	 GNU  sets optopt to val.

	 BSD  sets optopt to 0 (since val would never be returned).

     o	 Setting of optarg for long options without an argument that are invoked via '-W' ('W;' in option string):

	 GNU  sets optarg to the option name (the argument of '-W').

	 BSD  sets optarg to NULL (the argument of the long option).

     o	 Handling of '-W' with an argument that is not (a prefix to) a known long option ('W;' in option string):

	 GNU  returns '-W' with optarg set to the unknown option.

	 BSD  treats this as an error (unknown option) and returns '?' with optopt set to 0 and optarg set to NULL (as GNU's man page documents).

     o	 BSD does not permute the argument vector at the same points in the calling sequence as GNU does.  The aspects normally used by the caller
	 (ordering after -1 is returned, value of optind relative to current positions) are the same, though.  (We do fewer variable swaps.)

SEE ALSO

     getopt(3)

HISTORY

     The getopt_long() and getopt_long_only() functions first appeared in GNU libiberty.  The first BSD implementation of getopt_long() appeared
     in NetBSD 1.5, the first BSD implementation of getopt_long_only() in OpenBSD 3.3.	FreeBSD first included getopt_long() in FreeBSD 5.0,
     getopt_long_only() in FreeBSD 5.2.

BUGS

     The argv argument is not really const as its elements may be permuted (unless POSIXLY_CORRECT is set).

     The implementation can completely replace getopt(3), but right now we are using separate code.

BSD
								   April 1, 2000							       BSD