.\" $OpenBSD: getopt_long.3,v 1.10 2004/01/06 23:44:28 fgsch Exp $ .\" $NetBSD: getopt_long.3,v 1.11 2002/10/02 10:54:19 wiz Exp $ .\" .\" Copyright (c) 1988, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)getopt.3 8.5 (Berkeley) 4/27/95 .\" .Dd April 1, 2000 .Dt GETOPT_LONG 3 .Os .Sh NAME .Nm getopt_long , .Nm getopt_long_only .Nd get long options from command line argument list .Sh SYNOPSIS .Fd #include <getopt.h> .Vt extern char *optarg; .Vt extern int optind; .Vt extern int optopt; .Vt extern int opterr; .Vt extern int optreset; .Ft int .Fn getopt_long "int argc" "char * const *argv" "const char *optstring" "const struct option *longopts" "int *longindex" .Ft int .Fn getopt_long_only "int argc" "char * const *argv" "const char *optstring" "const struct option *longopts" "int *longindex" .Sh DESCRIPTION The .Fn getopt_long function is similar to .Xr getopt 3 but it accepts options in two forms: words and characters. The .Fn getopt_long function provides a superset of the functionality of .Xr getopt 3 . .Fn getopt_long 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, .Fn getopt_long behaves identically to .Xr getopt 3 . This is a good way to add long option processing to an existing program with the minimum of rewriting. .Pp In the second mechanism, a long option sets a flag in the .Fa option structure passed, or will store a pointer to the command line argument in the .Fa 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. .Bd -literal myprogram --myoption=somevalue .Ed .Pp When a long option is processed the call to .Fn getopt_long will return 0. For this reason, long option processing without shortcuts is not backwards compatible with .Xr getopt 3 . .Pp It is possible to combine these methods, providing for long options processing with short option equivalents for some options. Less frequently used options would be processed as long options only. .Pp The .Fn getopt_long call requires a structure to be initialized describing the long options. The structure is: .Bd -literal struct option { char *name; int has_arg; int *flag; int val; }; .Ed .Pp The .Fa name field should contain the option name without the leading double dash. .Pp The .Fa has_arg field should be one of: .Bl -tag -width "optional_argument" .It Li no_argument no argument to the option is expect. .It Li required_argument an argument to the option is required. .It Li optional_argument an argument to the option may be presented. .El .Pp If .Fa flag is not .Dv NULL , then the integer pointed to by it will be set to the value in the .Fa val field. If the .Fa flag field is .Dv NULL , then the .Fa val field will be returned. Setting .Fa flag to .Dv NULL and setting .Fa val to the corresponding short option will make this function act just like .Xr getopt 3 . .Pp If the .Fa longindex field is not .Dv NULL , then the integer pointed to by it will be set to the index of the long option relative to .Fa longopts . .Pp The last element of the .Fa longopts array has to be filled with zeroes. .Pp The .Fn getopt_long_only function behaves identically to .Fn getopt_long with the exception that long options may start with .Sq - in addition to .Sq -- . If an option starting with .Sq - does not match a long option but does match a single-character option, the single-character option is returned. .Sh RETURN VALUES If the .Fa flag field in .Li struct option is .Dv NULL , .Fn getopt_long and .Fn getopt_long_only return the value specified in the .Fa val field, which is usually just the corresponding short option. If .Fa flag is not .Dv NULL , these functions return 0 and store .Fa val in the location pointed to by .Fa flag . These functions return .Sq \: if there was a missing option argument, .Sq \&? if the user specified an unknown or ambiguous option, and \-1 when the argument list has been exhausted. .Sh EXAMPLES .Bd -literal -compact 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\en"); } break; default: usage(); } argc -= optind; argv += optind; .Ed .Sh IMPLEMENTATION DIFFERENCES This section describes differences to the GNU implementation found in glibc-2.1.3: .Bl -tag -width "xxx" .It Li o handling of - as first char of option string in presence of environment variable POSIXLY_CORRECT: .Bl -tag -width "OpenBSD" .It Li GNU ignores POSIXLY_CORRECT and returns non-options as arguments to option '\e1'. .It Li OpenBSD honors POSIXLY_CORRECT and stops at the first non-option. .El .It Li o handling of - within the option string (not the first character): .Bl -tag -width "OpenBSD" .It Li GNU treats a .Ql - on the command line as a non-argument. .It Li OpenBSD a .Ql - within the option string matches a .Ql - (single dash) on the command line. This functionality is provided for backward compatibility with programs, such as .Xr su 1 , that use .Ql - as an option flag. This practice is wrong, and should not be used in any current development. .El .It Li o handling of :: in options string in presence of POSIXLY_CORRECT: .Bl -tag -width "OpenBSD" .It Li Both GNU and OpenBSD ignore POSIXLY_CORRECT here and take :: to mean the preceding option takes an optional argument. .El .It Li o return value in case of missing argument if first character (after + or -) in option string is not ':': .Bl -tag -width "OpenBSD" .It Li GNU returns '?' .It OpenBSD returns ':' (since OpenBSD's getopt does). .El .It Li o handling of --a in getopt: .Bl -tag -width "OpenBSD" .It Li GNU parses this as option '-', option 'a'. .It Li OpenBSD parses this as '--', and returns \-1 (ignoring the a). (Because the original getopt does.) .El .It Li o setting of optopt for long options with flag != .Dv NULL : .Bl -tag -width "OpenBSD" .It Li GNU sets optopt to val. .It Li OpenBSD sets optopt to 0 (since val would never be returned). .El .It Li o handling of -W with W; in option string in getopt (not getopt_long): .Bl -tag -width "OpenBSD" .It Li GNU causes a segfault. .It Li OpenBSD no special handling is done; .Dq W; is interpreted as two separate options, neither of which take an argument. .El .It Li o setting of optarg for long options without an argument that are invoked via -W (W; in option string): .Bl -tag -width "OpenBSD" .It Li GNU sets optarg to the option name (the argument of -W). .It Li OpenBSD sets optarg to .Dv NULL (the argument of the long option). .El .It Li o handling of -W with an argument that is not (a prefix to) a known long option (W; in option string): .Bl -tag -width "OpenBSD" .It Li GNU returns -W with optarg set to the unknown option. .It Li OpenBSD treats this as an error (unknown option) and returns '?' with optopt set to 0 and optarg set to .Dv NULL (as GNU's man page documents). .El .It Li o The error messages are different. .It Li o OpenBSD 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.) .El .Sh ENVIRONMENT .Bl -tag -width POSIXLY_CORRECT .It Ev POSIXLY_CORRECT If set, option processing stops when the first non-option is found and a leading .Sq - or .Sq + in the .Ar optstring is ignored. .El .Sh SEE ALSO .Xr getopt 3 .Sh HISTORY The .Fn getopt_long and .Fn getopt_long_only functions first appeared in GNU libiberty. This implementation first appeared in .Ox 3.3 . .Sh BUGS The .Ar argv argument is not really .Dv const as its elements may be permuted (unless .Ev POSIXLY_CORRECT is set).