diff options
Diffstat (limited to 'lib/libc/stdlib/getopt.3')
| -rw-r--r-- | lib/libc/stdlib/getopt.3 | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/lib/libc/stdlib/getopt.3 b/lib/libc/stdlib/getopt.3 new file mode 100644 index 0000000..95ff6e6 --- /dev/null +++ b/lib/libc/stdlib/getopt.3 @@ -0,0 +1,252 @@ +.\" 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. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 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 8.4 (Berkeley) 4/19/94 +.\" +.Dd April 19, 1994 +.Dt GETOPT 3 +.Os BSD 4.3 +.Sh NAME +.Nm getopt +.Nd get option character from command line argument list +.Sh SYNOPSIS +.Fd #include <stdlib.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 variable +.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 an +.Dv EOF +when the argument list is exhausted, or a non-recognized +option is encountered. +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 an +.Dv EOF . +When all options have been processed (i.e., up to the first non-option +argument), +.Fn getopt +returns +.Dv EOF . +.Sh DIAGNOSTICS +If the +.Fn getopt +function encounters a character not found in the string +.Va optarg +or detects +a missing option argument it writes an error message and returns +.Ql ? +to the +.Em stderr . +Setting +.Va opterr +to a zero will disable these error messages. +If +.Va 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 EXTENSIONS +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 EXAMPLE +.Bd -literal -compact +extern char *optarg; +extern int optind; +int bflag, ch, fd; + +bflag = 0; +while ((ch = getopt(argc, argv, "bf:")) != EOF) + switch(ch) { + case 'b': + bflag = 1; + break; + case 'f': + if ((fd = open(optarg, O_RDONLY, 0)) < 0) { + (void)fprintf(stderr, + "myname: %s: %s\en", optarg, strerror(errno)); + exit(1); + } + break; + case '?': + default: + usage(); +} +argc -= optind; +argv += optind; +.Ed +.Sh HISTORY +The +.Fn getopt +function appeared +.Bx 4.3 . +.Sh BUGS +A single dash +.Dq Li - +may be specified as an 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 . +By default, a single dash causes +.Fn getopt +to return +.Dv EOF . +This is, we believe, compatible with System V. +.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 length; +char *p; + +while ((c = getopt(argc, argv, "0123456789")) != EOF) + switch (c) { + 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] == '-' && p[1] == ch && !p[2]) + length = atoi(++p); + else + length = atoi(argv[optind] + 1); + break; + } +} +.Ed |
