275 lines
8.1 KiB
Groff
275 lines
8.1 KiB
Groff
.\" $NetBSD: getopt_long.3,v 1.7 2002/02/07 09:24:06 ross Exp $
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.\"
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.\" Copyright (c) 1988, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getopt.3 8.5 (Berkeley) 4/27/95
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.\"
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.Dd April 1, 2000
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.Dt GETOPT_LONG 3
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.Os
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.Sh NAME
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.Nm getopt_long
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.Nd get long options from command line argument list
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include \*[Lt]getopt.h\*[Gt]
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.Ft int
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.Fn getopt_long "int argc" "char * const *argv" "const char *optstring" "struct options *long options" "int *index"
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.Sh DESCRIPTION
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The
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.Fn getopt_long
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function is similar to
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.Xr getopt 3
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but it accepts options in two forms: words and characters. The
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.Fn getopt_long
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function provides a superset of of the functionality of
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.Xr getopt 3 .
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.Fn getopt_long
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can be used in two ways. In the first way, every long option understood
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by the program has a corresponding short option, and the option
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structure is only used to translate from long options to short
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options. When used in this fashion,
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.Fn getopt_long
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behaves identically to
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.Xr getopt 3 .
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This is a good way to add long option processing to an existing program
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with the minimum of rewriting.
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.Pp
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In the second mechanism, a long option sets a flag in the
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.Fa option
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structure passed, or will store a pointer to the command line argument
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in the
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.Fa option
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structure passed to it for options that take arguments. Additionally,
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the long option's argument may be specified as a single argument with
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an equal sign, e.g.
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.Bd -literal
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myprogram --myoption=somevalue
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.Ed
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.Pp
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When a long option is processed the call to
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.Fn getopt_long
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will return 0. For this reason, long option processing without
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shortcuts is not backwards compatible with
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.Xr getopt 3 .
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.Pp
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It is possible to combine these methods, providing for long options
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processing with short option equivalents for some options. Less
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frequently used options would be processed as long options only.
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.Pp
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The
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.Fn getopt_long
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call requires a structure to be initialized describing the long
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options. The structure is:
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.Bd -literal
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struct option {
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char *name;
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int has_arg;
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int *flag;
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int val;
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};
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.Ed
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.Pp
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The
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.Fa name
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field should contain the option name without the leading double dash.
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.Pp
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The
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.Fa has_arg
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field should be one of:
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.Bl -tag -width "optional_argument"
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.It Li no_argument
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no argument to the option is expect.
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.It Li required_argument
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an argument to the option is required.
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.It Li optional_argument
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an argument to the option may be presented.
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.El
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.Pp
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If
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.Fa flag
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is non-NULL, then the integer pointed to by it will be set to the
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value in the
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.Fa val
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field. If the
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.Fa flag
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field is NULL, then the
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.Fa val
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field will be returned. Setting
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.Fa flag
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to NULL and setting
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.Fa val
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to the corresponding short option will make this function act just
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like
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.Xr getopt 3 .
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.Sh EXAMPLES
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.Bd -literal -compact
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extern char *optarg;
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extern int optind;
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int bflag, ch, fd;
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int daggerset;
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/* options descriptor */
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static struct option longopts[] = {
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{ "buffy", no_argument, 0, 'b' },
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{ "floride", required_argument, 0, 'f' },
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{ "daggerset", no_argument, \*[Am]daggerset, 1 },
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{ 0, 0, 0, 0 }
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};
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bflag = 0;
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while ((ch = getopt_long(argc, argv, "bf:", longopts, NULL)) != -1)
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switch(ch) {
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case 'b':
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bflag = 1;
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break;
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case 'f':
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if ((fd = open(optarg, O_RDONLY, 0)) \*[Lt] 0) {
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(void)fprintf(stderr,
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"myname: %s: %s\en", optarg, strerror(errno));
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exit(1);
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}
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break;
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case 0:
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if(daggerset) {
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fprintf(stderr,"Buffy will use her dagger to "
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"apply floride to dracula's teeth\en");
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}
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break;
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case '?':
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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.Ed
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.Sh IMPLEMENTATION DIFFERENCES
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This section describes differences to the GNU implementation
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found in glibc-2.1.3:
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.Bl -tag -width "xxx"
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.It Li o
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handling of - as first char of option string in presence of
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environment variable POSIXLY_CORRECT:
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.Bl -tag -width "NetBSD"
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.It Li GNU
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ignores POSIXLY_CORRECT and returns non-options as
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arguments to option '\e1'.
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.It Li NetBSD
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honors POSIXLY_CORRECT and stops at the first non-option.
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.El
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.It Li o
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handling of :: in options string in presence of POSIXLY_CORRECT:
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.Bl -tag -width "NetBSD"
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.It Li Both
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GNU and NetBSD ignore POSIXLY_CORRECT here and take :: to
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mean the preceding option takes an optional argument.
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.El
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.It Li o
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return value in case of missing argument if first character
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(after + or -) in option string is not ':':
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.Bl -tag -width "NetBSD"
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.It Li GNU
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returns '?'
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.It NetBSD
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returns ':' (since NetBSD's getopt does).
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.El
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.It Li o
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handling of --a in getopt:
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.Bl -tag -width "NetBSD"
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.It Li GNU
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parses this as option '-', option 'a'.
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.It Li NetBSD
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parses this as '--', and returns -1 (ignoring the a). (Because
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the original getopt does.)
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.El
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.It Li o
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setting of optopt for long options with flag != NULL:
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.Bl -tag -width "NetBSD"
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.It Li GNU
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sets optopt to val.
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.It Li NetBSD
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sets optopt to 0 (since val would never be returned).
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.El
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.It Li o
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handling of -W with W; in option string in getopt (not getopt_long):
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.Bl -tag -width "NetBSD"
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.It Li GNU
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causes a segfault.
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.It Li NetBSD
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returns -1, with optind pointing past the argument of -W
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(as if `-W arg' were `--arg', and thus '--' had been found).
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.\" How should we treat W; in the option string when called via
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.\" getopt? Ignore the ';' or treat it as a ':'? Issue a warning?
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.El
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.It Li o
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setting of optarg for long options without an argument that are
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invoked via -W (W; in option string):
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.Bl -tag -width "NetBSD"
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.It Li GNU
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sets optarg to the option name (the argument of -W).
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.It Li NetBSD
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sets optarg to NULL (the argument of the long option).
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.El
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.It Li o
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handling of -W with an argument that is not (a prefix to) a known
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long option (W; in option string):
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.Bl -tag -width "NetBSD"
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.It Li GNU
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returns -W with optarg set to the unknown option.
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.It Li NetBSD
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treats this as an error (unknown option) and returns '?' with
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optopt set to 0 and optarg set to NULL (as GNU's man page
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documents).
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.El
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.It Li o
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The error messages are different.
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.It Li o
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NetBSD does not permute the argument vector at the same points in
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the calling sequence as GNU does. The aspects normally used by
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the caller (ordering after -1 is returned, value of optind relative
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to current positions) are the same, though. (We do fewer variable
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swaps.)
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.El
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.Sh SEE ALSO
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.Xr getopt 3
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.Sh HISTORY
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The
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.Fn getopt_long
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function first appeared in GNU libiberty. The first
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.Nx
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implementation appeared in 1.5.
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.Sh BUGS
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The implementation, can completelely replace
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.Xr getopt 3 ,
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but right now we are using separate code.
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