diff options
Diffstat (limited to 'lib/libc/stdlib/getopt.3')
| -rw-r--r-- | lib/libc/stdlib/getopt.3 | 306 |
1 files changed, 306 insertions, 0 deletions
diff --git a/lib/libc/stdlib/getopt.3 b/lib/libc/stdlib/getopt.3 new file mode 100644 index 0000000..3fe4453 --- /dev/null +++ b/lib/libc/stdlib/getopt.3 @@ -0,0 +1,306 @@ +.\" $NetBSD: getopt.3,v 1.31 2003/09/23 10:26:54 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. +.\" 4. 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 +.\" $FreeBSD$ +.\" +.Dd April 27, 1995 +.Dt GETOPT 3 +.Os +.Sh NAME +.Nm getopt +.Nd get option character from command line argument list +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In unistd.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 "int argc" "char * const argv[]" "const char *optstring" +.Sh DESCRIPTION +The +.Fn getopt +function incrementally parses a command line argument list +.Fa argv +and returns the next +.Em known +option character. +An option character is +.Em known +if it has been specified in the string of accepted option characters, +.Fa optstring . +.Pp +The option string +.Fa optstring +may contain the following elements: individual characters, and +characters followed by a colon to indicate an option argument +is to follow. +For example, an option string +.Li \&"x" +recognizes an option +.Dq Fl x , +and an option string +.Li \&"x:" +recognizes an option and argument +.Dq Fl x Ar argument . +It does not matter to +.Fn getopt +if a following argument has leading white space. +.Pp +On return from +.Fn getopt , +.Va optarg +points to an option argument, if it is anticipated, +and the variable +.Va optind +contains the index to the next +.Fa argv +argument for a subsequent call +to +.Fn getopt . +The variable +.Va optopt +saves the last +.Em known +option character returned by +.Fn getopt . +.Pp +The variables +.Va opterr +and +.Va optind +are both initialized to 1. +The +.Va optind +variable may be set to another value before a set of calls to +.Fn getopt +in order to skip over more or less argv entries. +.Pp +In order to use +.Fn getopt +to evaluate multiple sets of arguments, or to evaluate a single set of +arguments multiple times, +the variable +.Va optreset +must be set to 1 before the second and each additional set of calls to +.Fn getopt , +and the variable +.Va optind +must be reinitialized. +.Pp +The +.Fn getopt +function returns \-1 when the argument list is exhausted. +The interpretation of options in the argument list may be cancelled +by the option +.Ql -- +(double dash) which causes +.Fn getopt +to signal the end of argument processing and return \-1. +When all options have been processed (i.e., up to the first non-option +argument), +.Fn getopt +returns \-1. +.Sh RETURN VALUES +The +.Fn getopt +function returns the next known option character in +.Fa optstring . +If +.Fn getopt +encounters a character not found in +.Fa optstring +or if it detects a missing option argument, +it returns +.Ql \&? +(question mark). +If +.Fa optstring +has a leading +.Ql \&: +then a missing option argument causes +.Ql \&: +to be returned instead of +.Ql \&? . +In either case, the variable +.Va optopt +is set to the character that caused the error. +The +.Fn getopt +function returns \-1 when the argument list is exhausted. +.Sh EXAMPLES +.Bd -literal -compact +#include <unistd.h> +int bflag, ch, fd; + +bflag = 0; +while ((ch = getopt(argc, argv, "bf:")) != -1) { + switch (ch) { + case 'b': + bflag = 1; + break; + case 'f': + if ((fd = open(optarg, O_RDONLY, 0)) \*[Lt] 0) { + (void)fprintf(stderr, + "myname: %s: %s\en", optarg, strerror(errno)); + exit(1); + } + break; + case '?': + default: + usage(); + } +} +argc -= optind; +argv += optind; +.Ed +.Sh DIAGNOSTICS +If the +.Fn getopt +function encounters a character not found in the string +.Fa optstring +or detects +a missing option argument it writes an error message to the +.Dv stderr +and returns +.Ql \&? . +Setting +.Va opterr +to a zero will disable these error messages. +If +.Fa optstring +has a leading +.Ql \&: +then a missing option argument causes a +.Ql \&: +to be returned in addition to suppressing any error messages. +.Pp +Option arguments are allowed to begin with +.Dq Li \- ; +this is reasonable but reduces the amount of error checking possible. +.Sh SEE ALSO +.Xr getopt 1 , +.Xr getopt_long 3 , +.Xr getsubopt 3 +.Sh STANDARDS +The +.Va optreset +variable was added to make it possible to call the +.Fn getopt +function multiple times. +This is an extension to the +.St -p1003.2 +specification. +.Sh HISTORY +The +.Fn getopt +function appeared in +.Bx 4.3 . +.Sh BUGS +The +.Fn getopt +function was once specified to return +.Dv EOF +instead of \-1. +This was changed by +.St -p1003.2-92 +to decouple +.Fn getopt +from +.In stdio.h . +.Pp +A single dash +.Dq Li - +may be specified as a character in +.Fa optstring , +however it should +.Em never +have an argument associated with it. +This allows +.Fn getopt +to be used with programs that expect +.Dq Li - +as an option flag. +This practice is wrong, and should not be used in any current development. +It is provided for backward compatibility +.Em only . +Care should be taken not to use +.Ql \&- +as the first character in +.Fa optstring +to avoid a semantic conflict with +.Tn GNU +.Fn getopt , +which assigns different meaning to an +.Fa optstring +that begins with a +.Ql \&- . +By default, a single dash causes +.Fn getopt +to return \-1. +.Pp +It is also possible to handle digits as option letters. +This allows +.Fn getopt +to be used with programs that expect a number +.Pq Dq Li \&-\&3 +as an option. +This practice is wrong, and should not be used in any current development. +It is provided for backward compatibility +.Em only . +The following code fragment works in most cases. +.Bd -literal -offset indent +int ch; +long length; +char *p, *ep; + +while ((ch = getopt(argc, argv, "0123456789")) != -1) + switch (ch) { + case '0': case '1': case '2': case '3': case '4': + case '5': case '6': case '7': case '8': case '9': + p = argv[optind - 1]; + if (p[0] == '-' \*[Am]\*[Am] p[1] == ch \*[Am]\*[Am] !p[2]) { + length = ch - '0'; + ep = ""; + } else if (argv[optind] \*[Am]\*[Am] argv[optind][1] == ch) { + length = strtol((p = argv[optind] + 1), + \*[Am]ep, 10); + optind++; + optreset = 1; + } else + usage(); + if (*ep != '\e0') + errx(EX_USAGE, "illegal number -- %s", p); + break; + } +.Ed |
