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GETOPT_LONG(3)		     Library Functions Manual		  GETOPT_LONG(3)

NAME
     getopt_long,  getopt_long_only  -- get long options from command line argu-
     ment 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  pro-
     cessing  with  short  option equivalents for some options.  Less frequently
     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
     usually  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.

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\n");
		     }
		     break;
	     default:
		     usage();
     }
     argc -= optind;
     argv += optind;

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

     *	 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).

     *	 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).

     *	 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 docu-
	      ments).

     *	 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 po-
	 sitions) are the same, though.  (We do fewer variable swaps.)

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

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  (un-
     less POSIXLY_CORRECT is set).

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

FreeBSD 5.3			  April 1, 2000 		  GETOPT_LONG(3)
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