1.\" $NetBSD: getopt_long.3,v 1.14 2003/08/07 16:43:40 agc Exp $ 2.\" $DragonFly: src/lib/libc/stdlib/getopt_long.3,v 1.6 2007/05/12 21:22:10 swildner 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 March 14, 2007 34.Dt GETOPT_LONG 3 35.Os 36.Sh NAME 37.Nm getopt_long 38.Nd get long options from command line argument list 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In getopt.h 43.Ft int 44.Fn getopt_long "int argc" "char * const *argv" "const char *optstring" "struct option *long_options" "int *index" 45.Fn getopt_long_only "int argc" "char * const *argv" "const char *optstring" "struct option *long_options" "int *index" 46.Sh DESCRIPTION 47The 48.Fn getopt_long 49function is similar to 50.Xr getopt 3 51but it accepts options in two forms: words and characters. 52The 53.Fn getopt_long 54function provides a superset of the functionality of 55.Xr getopt 3 . 56.Fn getopt_long 57can be used in two ways. 58In the first way, every long option understood by the program has a 59corresponding short option, and the option structure is only used to 60translate from long options to short options. 61When used in this fashion, 62.Fn getopt_long 63behaves identically to 64.Xr getopt 3 . 65This is a good way to add long option processing to an existing program 66with the minimum of rewriting. 67.Pp 68In the second mechanism, a long option sets a flag in the 69.Fa option 70structure passed, or will store a pointer to the command line argument 71in the 72.Fa option 73structure passed to it for options that take arguments. 74Additionally, the long option's argument may be specified as a single 75argument with an equal sign, e.g. 76.Bd -literal 77myprogram --myoption=somevalue 78.Ed 79.Pp 80When a long option is processed the call to 81.Fn getopt_long 82will return 0. 83For this reason, long option processing without 84shortcuts is not backwards compatible with 85.Xr getopt 3 . 86.Pp 87It is possible to combine these methods, providing for long options 88processing with short option equivalents for some options. 89Less frequently used options would be processed as long options only. 90.Pp 91The 92.Fn getopt_long 93call requires a structure to be initialized describing the long options. 94The structure is: 95.Bd -literal 96struct option { 97 char *name; 98 int has_arg; 99 int *flag; 100 int val; 101}; 102.Ed 103.Pp 104The 105.Fa name 106field should contain the option name without the leading double dash. 107.Pp 108The 109.Fa has_arg 110field should be one of: 111.Bl -tag -width "optional_argument" 112.It Li no_argument 113no argument to the option is expect. 114.It Li required_argument 115an argument to the option is required. 116.It Li optional_argument 117an argument to the option may be presented. 118.El 119.Pp 120If 121.Fa flag 122is not 123.Dv NULL , 124then the integer pointed to by it will be set to the value in the 125.Fa val 126field. 127If the 128.Fa flag 129field is 130.Dv NULL , 131then the 132.Fa val 133field will be returned. 134Setting 135.Fa flag 136to 137.Dv NULL 138and setting 139.Fa val 140to the corresponding short option will make this function act just 141like 142.Xr getopt 3 . 143.Pp 144If the 145.Fa index 146field is not 147.Dv NULL , 148the integer it points to will be set to the index of the long option 149in the 150.Fa long_options 151array. 152.Pp 153The last element of the 154.Fa long_options 155array has to be filled with zeroes (see 156.Sx EXAMPLES 157section). 158.Pp 159The 160.Fn getopt_long_only 161function behaves identically to 162.Fn getopt_long 163with the exception that long options may start with 164.Ql - 165in addition to 166.Ql -- . 167If an option starting with 168.Ql - 169does not match a long option but does match a single-character option, 170the single-character option is returned. 171Note that the 172.Fn getopt_long_only 173function is deprecated. 174New programs should use 175.Fn getopt_long . 176.Sh IMPLEMENTATION DIFFERENCES 177This section describes differences to the GNU implementation 178found in glibc-2.1.3: 179.Bl -tag -width "xxx" 180.It Li o 181handling of - as first char of option string in presence of 182environment variable POSIXLY_CORRECT: 183.Bl -tag -width "NetBSD" 184.It Li GNU 185ignores POSIXLY_CORRECT and returns non-options as 186arguments to option '\e1'. 187.It Li NetBSD 188honors POSIXLY_CORRECT and stops at the first non-option. 189.El 190.It Li o 191handling of :: in options string in presence of POSIXLY_CORRECT: 192.Bl -tag -width "NetBSD" 193.It Li Both 194GNU and 195.Nx 196ignore POSIXLY_CORRECT here and take :: to 197mean the preceding option takes an optional argument. 198.El 199.It Li o 200return value in case of missing argument if first character 201(after + or -) in option string is not ':': 202.Bl -tag -width "NetBSD" 203.It Li GNU 204returns '?' 205.It NetBSD 206returns ':' (since 207.Nx Ap s 208getopt does). 209.El 210.It Li o 211handling of --a in getopt: 212.Bl -tag -width "NetBSD" 213.It Li GNU 214parses this as option '-', option 'a'. 215.It Li NetBSD 216parses this as '--', and returns \-1 (ignoring the a). 217(Because the original getopt does.) 218.El 219.It Li o 220setting of optopt for long options with flag != 221.Dv NULL : 222.Bl -tag -width "NetBSD" 223.It Li GNU 224sets optopt to val. 225.It Li NetBSD 226sets optopt to 0 (since val would never be returned). 227.El 228.It Li o 229handling of -W with W; in option string in getopt (not getopt_long): 230.Bl -tag -width "NetBSD" 231.It Li GNU 232causes a segfault. 233.It Li NetBSD 234returns \-1, with optind pointing past the argument of -W 235(as if `-W arg' were `--arg', and thus '--' had been found). 236.\" How should we treat W; in the option string when called via 237.\" getopt? Ignore the ';' or treat it as a ':'? Issue a warning? 238.El 239.It Li o 240setting of optarg for long options without an argument that are 241invoked via -W (W; in option string): 242.Bl -tag -width "NetBSD" 243.It Li GNU 244sets optarg to the option name (the argument of -W). 245.It Li NetBSD 246sets optarg to 247.Dv NULL 248(the argument of the long option). 249.El 250.It Li o 251handling of -W with an argument that is not (a prefix to) a known 252long option (W; in option string): 253.Bl -tag -width "NetBSD" 254.It Li GNU 255returns -W with optarg set to the unknown option. 256.It Li NetBSD 257treats this as an error (unknown option) and returns '?' with 258optopt set to 0 and optarg set to 259.Dv NULL 260(as GNU's man page documents). 261.El 262.It Li o 263The error messages are different. 264.It Li o 265.Nx 266does not permute the argument vector at the same points in 267the calling sequence as GNU does. 268The aspects normally used by the caller 269(ordering after \-1 is returned, value of optind relative 270to current positions) are the same, though. 271(We do fewer variable swaps.) 272.El 273.Sh EXAMPLES 274.Bd -literal -compact 275extern char *optarg; 276extern int optind; 277int bflag, ch, fd; 278int daggerset; 279 280/* options descriptor */ 281static struct option longopts[] = { 282 { "buffy", no_argument, 0, 'b' }, 283 { "fluoride", required_argument, 0, 'f' }, 284 { "daggerset", no_argument, \*[Am]daggerset, 1 }, 285 { NULL, 0, NULL, 0 } 286}; 287 288bflag = 0; 289while ((ch = getopt_long(argc, argv, "bf:", longopts, NULL)) != -1) 290 switch (ch) { 291 case 'b': 292 bflag = 1; 293 break; 294 case 'f': 295 if ((fd = open(optarg, O_RDONLY, 0)) \*[Lt] 0) { 296 (void)fprintf(stderr, 297 "myname: %s: %s\en", optarg, strerror(errno)); 298 exit(1); 299 } 300 break; 301 case 0: 302 if(daggerset) { 303 fprintf(stderr,"Buffy will use her dagger to " 304 "apply fluoride to dracula's teeth\en"); 305 } 306 break; 307 case '?': 308 default: 309 usage(); 310} 311argc -= optind; 312argv += optind; 313.Ed 314.Sh SEE ALSO 315.Xr getopt 3 316.Sh HISTORY 317The 318.Fn getopt_long 319function first appeared in GNU libiberty. 320The first 321.Nx 322implementation appeared in 1.5. 323