1.\" $OpenBSD: getopt_long.3,v 1.8 2003/06/02 20:18:37 millert Exp $ 2.\" $NetBSD: getopt_long.3,v 1.11 2002/10/02 10:54:19 wiz Exp $ 3.\" 4.\" Copyright (c) 1988, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)getopt.3 8.5 (Berkeley) 4/27/95 32.\" 33.Dd April 1, 2000 34.Dt GETOPT_LONG 3 35.Os 36.Sh NAME 37.Nm getopt_long , 38.Nm getopt_long_only 39.Nd get long options from command line argument list 40.Sh SYNOPSIS 41.Fd #include <getopt.h> 42.Vt extern char *optarg; 43.Vt extern int optind; 44.Vt extern int optopt; 45.Vt extern int opterr; 46.Vt extern int optreset; 47.Ft int 48.Fn getopt_long "int argc" "char * const *argv" "const char *optstring" "const struct option *longopts" "int *index" 49.Ft int 50.Fn getopt_long_only "int argc" "char * const *argv" "const char *optstring" "const struct option *longopts" "int *index" 51.Sh DESCRIPTION 52The 53.Fn getopt_long 54function is similar to 55.Xr getopt 3 56but it accepts options in two forms: words and characters. 57The 58.Fn getopt_long 59function provides a superset of the functionality of 60.Xr getopt 3 . 61.Fn getopt_long 62can be used in two ways. 63In the first way, every long option understood by the program has a 64corresponding short option, and the option structure is only used to 65translate from long options to short options. 66When used in this fashion, 67.Fn getopt_long 68behaves identically to 69.Xr getopt 3 . 70This is a good way to add long option processing to an existing program 71with the minimum of rewriting. 72.Pp 73In the second mechanism, a long option sets a flag in the 74.Fa option 75structure passed, or will store a pointer to the command line argument 76in the 77.Fa option 78structure passed to it for options that take arguments. 79Additionally, the long option's argument may be specified as a single 80argument with an equal sign, e.g. 81.Bd -literal 82myprogram --myoption=somevalue 83.Ed 84.Pp 85When a long option is processed the call to 86.Fn getopt_long 87will return 0. 88For this reason, long option processing without 89shortcuts is not backwards compatible with 90.Xr getopt 3 . 91.Pp 92It is possible to combine these methods, providing for long options 93processing with short option equivalents for some options. 94Less frequently used options would be processed as long options only. 95.Pp 96The 97.Fn getopt_long 98call requires a structure to be initialized describing the long 99options. 100The structure is: 101.Bd -literal 102struct option { 103 char *name; 104 int has_arg; 105 int *flag; 106 int val; 107}; 108.Ed 109.Pp 110The 111.Fa name 112field should contain the option name without the leading double dash. 113.Pp 114The 115.Fa has_arg 116field should be one of: 117.Bl -tag -width "optional_argument" 118.It Li no_argument 119no argument to the option is expect. 120.It Li required_argument 121an argument to the option is required. 122.It Li optional_argument 123an argument to the option may be presented. 124.El 125.Pp 126If 127.Fa flag 128is not 129.Dv NULL , 130then the integer pointed to by it will be set to the value in the 131.Fa val 132field. 133If the 134.Fa flag 135field is 136.Dv NULL , 137then the 138.Fa val 139field will be returned. 140Setting 141.Fa flag 142to 143.Dv NULL 144and setting 145.Fa val 146to the corresponding short option will make this function act just 147like 148.Xr getopt 3 . 149.Pp 150The 151.Fn getopt_long_only 152function behaves identically to 153.Fn getopt_long 154with the exception that long options may start with 155.Sq - 156in addition to 157.Sq -- . 158If an option starting with 159.Sq - 160does not match a long option but does match a single-character option, 161the single-character option is returned. 162.Sh RETURN VALUES 163If the 164.Fa flag 165field in 166.Li struct option 167is 168.Dv NULL , 169.Fn getopt_long 170and 171.Fn getopt_long_only 172return the value specified in the 173.Fa val 174field, which is usually just the corresponding short option. 175If 176.Fa flag 177is not 178.Dv NULL , 179these functions return 0 and store 180.Fa val 181in the location pointed to by 182.Fa flag . 183These functions return 184.Sq \: 185if there was a missing option argument, 186.Sq ? 187if the user specified an unknown or ambiguous option, and 188\-1 when the argument list has been exhausted. 189.Sh EXAMPLES 190.Bd -literal -compact 191int bflag, ch, fd; 192int daggerset; 193 194/* options descriptor */ 195static struct option longopts[] = { 196 { "buffy", no_argument, 0, 'b' }, 197 { "fluoride", required_argument, 0, 'f' }, 198 { "daggerset", no_argument, &daggerset, 1 }, 199 { 0, 0, 0, 0 } 200}; 201 202bflag = 0; 203while ((ch = getopt_long(argc, argv, "bf:", longopts, NULL)) != -1) 204 switch(ch) { 205 case 'b': 206 bflag = 1; 207 break; 208 case 'f': 209 if ((fd = open(optarg, O_RDONLY, 0)) == -1) 210 err(1, "unable to open %s", optarg); 211 break; 212 case 0: 213 if (daggerset) { 214 fprintf(stderr,"Buffy will use her dagger to " 215 "apply fluoride to dracula's teeth\en"); 216 } 217 break; 218 case '?': 219 default: 220 usage(); 221} 222argc -= optind; 223argv += optind; 224.Ed 225.Sh IMPLEMENTATION DIFFERENCES 226This section describes differences to the GNU implementation 227found in glibc-2.1.3: 228.Bl -tag -width "xxx" 229.It Li o 230handling of - as first char of option string in presence of 231environment variable POSIXLY_CORRECT: 232.Bl -tag -width "OpenBSD" 233.It Li GNU 234ignores POSIXLY_CORRECT and returns non-options as 235arguments to option '\e1'. 236.It Li OpenBSD 237honors POSIXLY_CORRECT and stops at the first non-option. 238.El 239.It Li o 240handling of - within the option string (not the first character): 241.Bl -tag -width "OpenBSD" 242.It Li GNU 243treats a 244.Ql - 245on the command line as a non-argument. 246.It Li OpenBSD 247a 248.Ql - 249within the option string matches a 250.Ql - 251(single dash) on the command line. 252This functionality is provided for backward compatibility with 253programs, such as 254.Xr su 1 , 255that use 256.Ql - 257as an option flag. 258This practice is wrong, and should not be used in any current development. 259.El 260.It Li o 261handling of :: in options string in presence of POSIXLY_CORRECT: 262.Bl -tag -width "OpenBSD" 263.It Li Both 264GNU and OpenBSD ignore POSIXLY_CORRECT here and take :: to 265mean the preceding option takes an optional argument. 266.El 267.It Li o 268return value in case of missing argument if first character 269(after + or -) in option string is not ':': 270.Bl -tag -width "OpenBSD" 271.It Li GNU 272returns '?' 273.It OpenBSD 274returns ':' (since OpenBSD's getopt does). 275.El 276.It Li o 277handling of --a in getopt: 278.Bl -tag -width "OpenBSD" 279.It Li GNU 280parses this as option '-', option 'a'. 281.It Li OpenBSD 282parses this as '--', and returns \-1 (ignoring the a). 283(Because the original getopt does.) 284.El 285.It Li o 286setting of optopt for long options with flag != 287.Dv NULL : 288.Bl -tag -width "OpenBSD" 289.It Li GNU 290sets optopt to val. 291.It Li OpenBSD 292sets optopt to 0 (since val would never be returned). 293.El 294.It Li o 295handling of -W with W; in option string in getopt (not getopt_long): 296.Bl -tag -width "OpenBSD" 297.It Li GNU 298causes a segfault. 299.It Li OpenBSD 300no special handling is done; 301.Dq W; 302is interpreted as two separate options, neither of which take an argument. 303.El 304.It Li o 305setting of optarg for long options without an argument that are 306invoked via -W (W; in option string): 307.Bl -tag -width "OpenBSD" 308.It Li GNU 309sets optarg to the option name (the argument of -W). 310.It Li OpenBSD 311sets optarg to 312.Dv NULL 313(the argument of the long option). 314.El 315.It Li o 316handling of -W with an argument that is not (a prefix to) a known 317long option (W; in option string): 318.Bl -tag -width "OpenBSD" 319.It Li GNU 320returns -W with optarg set to the unknown option. 321.It Li OpenBSD 322treats this as an error (unknown option) and returns '?' with 323optopt set to 0 and optarg set to 324.Dv NULL 325(as GNU's man page documents). 326.El 327.It Li o 328The error messages are different. 329.It Li o 330OpenBSD does not permute the argument vector at the same points in 331the calling sequence as GNU does. 332The aspects normally used by the caller 333(ordering after \-1 is returned, value of optind relative 334to current positions) are the same, though. 335(We do fewer variable swaps.) 336.El 337.Sh ENVIRONMENT 338.Bl -tag -width POSIXLY_CORRECT 339.It Ev POSIXLY_CORRECT 340If set, option processing stops when the first non-option is found and 341a leading 342.Sq - 343or 344.Sq + 345in the 346.Ar optstring 347is ignored. 348.El 349.Sh SEE ALSO 350.Xr getopt 3 351.Sh HISTORY 352The 353.Fn getopt_long 354and 355.Fn getopt_long_only 356functions first appeared in GNU libiberty. 357This implementation first appeared in 358.Ox 3.3 . 359.Sh BUGS 360The 361.Ar argv 362argument is not really 363.Dv const 364as its elements may be permuted (unless 365.Ev POSIXLY_CORRECT 366is set). 367