311 lines
7.3 KiB
Groff
311 lines
7.3 KiB
Groff
.\" $NetBSD: getopt.3,v 1.34 2014/06/05 22:09:50 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.
|
|
.\" 3. 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
|
|
.\"
|
|
.Dd June 5, 2014
|
|
.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.
|
|
If an individual character is followed by two colons, then the
|
|
option argument is optional;
|
|
.Va optarg
|
|
is set to the rest of the current
|
|
.Va argv
|
|
word, or
|
|
.Dv NULL
|
|
if there were no more characters in the current word.
|
|
This is a
|
|
.Nx
|
|
extension.
|
|
For example, an option string
|
|
.Qq x
|
|
recognizes an option
|
|
.Dq Fl x ,
|
|
and an option string
|
|
.Qq x:
|
|
recognizes an option and argument
|
|
.Dq Fl x Ar argument .
|
|
It does not matter to
|
|
.Fn getopt
|
|
if a following argument has leading whitespace.
|
|
.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
|
|
.Dq --
|
|
(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
|
|
.Sq \&?
|
|
(question mark).
|
|
If
|
|
.Fa optstring
|
|
has a leading
|
|
.Sq \&:
|
|
then a missing option argument causes
|
|
.Sq \&:
|
|
to be returned instead of
|
|
.Sq \&? .
|
|
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
|
|
extern char *optarg;
|
|
extern int optind;
|
|
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
|
|
.Em stderr
|
|
and returns
|
|
.Sq \&? .
|
|
Setting
|
|
.Va opterr
|
|
to a zero will disable these error messages.
|
|
If
|
|
.Fa optstring
|
|
has a leading
|
|
.Sq \&:
|
|
then a missing option argument causes a
|
|
.Sq \&:
|
|
to be returned in addition to suppressing any error messages.
|
|
.Pp
|
|
Option arguments are allowed to begin with
|
|
.Sq - ;
|
|
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
|
|
.Pq Sq -
|
|
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
|
|
.Sq -
|
|
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
|
|
.Sq -
|
|
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
|
|
.Sq - .
|
|
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;
|
|
|
|
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';
|
|
else
|
|
length = strtol(argv[optind] + 1, NULL, 10);
|
|
break;
|
|
}
|
|
}
|
|
.Ed
|