.\" $Id: Cgetopt.man 3515 2010-04-05 07:51:26Z baud $
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.\"	The Regents of the University of California.  All rights reserved.
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.\"     @(#)getopt.3	8.5 (Berkeley) 4/27/95
.\"
.TH CGETOPT_LONG "3" "$Date: 2010-04-05 09:51:26 +0200 (Mon, 05 Apr 2010) $" "CASTOR" "Common Library"
.SH NAME
Cgetopt_long - get long options from command line argument list
.SH SYNOPSIS
.BI "#include <Cgetopt.h>"
.sp
.BI "int Cgetopt (int " argc ", char **" argv ", char *" optstring ")"
.br
.BI "int Cgetopt_long (int " argc ", char **" argv ", char *" optstring ", Coptions_t *" long_options ", int *" index ")"

.SH DESCRIPTION
The
.B Cgetopt
function incrementally parses a command line argument list
.I argv
and returns the next known option character. An option character is known if it has been specified in the string of accepted option characters
.IR optstring .
.P
The 
.B Cgetopt_long
function is similar to 
.B Cgetopt
but it accepts options in two forms: words and characters. The
.B Cgetopt_long
function provides a superset of the functionality of 
.BR Cgetopt .
The additional functionality is described in the section CGETOPT_LONG.
.P
The option string
.I 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
.B x
recognizes an option
.B x ,
and an option string
.B x:
recognizes an option
.B x
taking an argument.
It does not matter to
.B Cgetopt
if a following argument has leading white space.
.P
On return from
.BR Cgetopt ,
.B Coptarg
points to an option argument, if it is anticipated, and the variable
.B Coptind
contains the index to the next
.I argv
argument for a subsequent call to
.BR Cgetopt .
The variable
.B Coptopt
saves the last known option character returned by
.BR Cgetopt .
.P
The variables
.B Copterr
and
.B Coptind
are both initialized to 1.
The
.B Coptind
variable may be set to another value before a set of calls to
.B Cgetopt
in order to skip over more or less argv entries.
.P
In order to use
.B Cgetopt
to evaluate multiple sets of arguments, or to evaluate a single set of arguments multiple times, the variable
.B Coptreset
must be set to 1 before the second and each additional set of calls to
.B Cgetopt
and the variable
.B Coptind
must be reinitialized.
.P
The
.B Cgetopt
function returns -1 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
.B --
(double dash) which causes
.B Cgetopt
to signal the end of argument processing and returns -1. When all options have been processed (i.e., up to the first non-option argument),
.B Cgetopt
returns -1.
.S CGETOPT_LONG
.P
.B Cgetopt_long
can be used in two ways. In the first way, every long option understood by the program has a coresponding short option, and the option structure is only used to translate from long option to short options. When used in this fashion, 
.B Cgetopt_long
behaves identically to 
.BR Cgetopt .
This is good way to add long option processing to an existing program with the minimum of rewriting.
.P
In the second mechanism, a long option set a flag in the 
.B Coptions_t
structure passed, or will store a pointer to the command line argument in the 
.B Coptions_t
structure passed to it for options that take arguments. Additionally, the long option's argument may be specified as a single argument with an equal sign, e.g
.B myprogram --myoption=somevalue
.P
When a long option is processed the call to 
.B Cgetopt_long
will return 0. For this reason, long option processing without shortcuts are not backwards compatible with 
.B Cgetopt.
.P
It is possible to combine these methods, providing for long options processing with short option equivalents for some options. Less frequently used options would be processed as long options only.
.SH USAGE OF CGETOPT_LONG
.P
The 
.B Cgetopt_long
call requires a structure to be initialized describing the long options. The structure is:
.B
.ft CW
.nf
.sp
Coptions_t {
    char *name;
    int has_arg;
    int *flag;
    int val;
};
.ft
.LP
.fi

.P
The 
.I name
field should contain the option name without the leading double dash.
.P
The 
.I has_arg
field should be one of:
.B NO_ARGUMENT
if no argument to the option is expected,
.B REQUIRED_ARGUMENT
if an argument to the option is required or
.B OPTIONAL_ARGUMENT
if an argument to the option may be presented.
.P
If
.I flag
is non-NULL, then the integer pointed to by it will set to the value in the 
.I val
field. If the 
.I flag 
field is NULL, then the 
.I val
field will be returned. Setting 
.I flag
to NULL and setting
.I val
to the corresponding short option will make this function act just
like
.BR Cgetopt .
.SH DIAGNOSTICS
If the
.B Cgetopt
function encounters a character not found in the string
.I optstring
or detects a missing option argument it writes an error message to
.B stderr
and returns
.BR ? .
Setting
.B Copterr
to a zero will disable these error messages.
If
.I optstring
has a leading
.B :
then a missing option argument causes a
.B :
to be returned in addition to suppressing any error messages.
.P
Option arguments are allowed to begin with
.B -
; this is reasonable but reduces the amount of error checking possible.
.SH CGETOPT_LONG EXTENSIONS
The
.B Coptreset
variable was added to make it possible to call the
.B Cgetopt
function multiple times.
This is an extension to the
.B -p1003.2
specification.
.SH EXAMPLE
.ft CW
.nf
.sp
#include <Cgetopt.h>
int bflag, ch, fd;

Coptind = 1;            /* Required */
Copterr = 1;            /* Some stderr output if you want */

bflag = 0;
while ((ch = Cgetopt(argc, argv, "bf:")) != -1)
	switch(ch) {
	case 'b':
		bflag = 1;
		break;
	case 'f':
		if ((fd = open(Coptarg, O_RDONLY, 0)) < 0) {
			(void)fprintf(stderr,
			    "myname: %s: %s\en", Coptarg, strerror(errno));
			exit(1);
		}
		break;
	case '?':
	default:
		usage();
}
argc -= Coptind;
argv += Coptind;
.ft
.LP
.fi

.SH LONG EXAMPLE 
.ft CW
.nf
.sp
#include <Cgetopt.h>
int bflag, ch, fd;
int daggerset;

/* options descriptor */
Coptions_t longopts[] =
{
  {"buffy",       NO_ARGUMENT,        NULL,      'b'},
  {"floride",     REQUIRED_ARGUMENT,  NULL,      'f'},
  {"daggerset",   NO_ARGUMENT,        &daggerset,  1},
  {NULL,          0,                  NULL,        0}
};

Coptind = 1;            /* Required */
Copterr = 1;            /* Some stderr output if you want */

bflag = 0;
while ((ch = Cgetopt_long(argc, argv, "bf:", longopts, NULL)) != -1)
	switch(ch) {
	case 'b':
		bflag = 1;
		break;
	case 'f':
		if ((fd = open(Coptarg, O_RDONLY, 0)) < 0) {
			(void)fprintf(stderr,
			    "myname: %s: %s\en", Coptarg, strerror(errno));
			exit(1);
		}
		break;
	case 0:
		if(daggerset) {
			fprintf(stderr,"Buffy will put use her dagger"
				       "to apply floride to dracula's teeth");
		}
		break;
	case '?':
	default:
		usage();
}
argc -= Coptind;
argv += Coptind;
.ft
.LP
.fi

.SH HISTORY
The
.B Cgetopt
function appeared in BSD 4.3.
The 
.B Cgetopt_long
function first appeared in GNU library. This implementation was imported to NetBSD from a Kerberos distribution.
.SH BUGS
The
.B Cgetopt
function was once specified to return
.B EOF
instead of -1. This was changed by
.B -p1003.2-92
to decouple
.B Cgetopt
from <stdio.h>.
.P
A single dash
.B -
may be specified as an character in
.IR optstring ,
however it should
.B never
have an argument associated with it.
This allows
.B Cgetopt
to be used with programs that expect
.B -
as an option flag.
This practice is wrong, and should not be used in any current development.
It is provided for backward compatibility
.BR only .
By default, a single dash causes
.B Cgetopt
to return -1.
This is, we believe, compatible with System V.
.P
It is also possible to handle digits as option letters.
This allows
.B Cgetopt
to be used with programs that expect a number
.B -3
as an option.
This practice is wrong, and should not be used in any current development.
It is provided for backward compatibility
.BR only .
The following code fragment works in most cases.
.ft CW
.nf
.sp
int length;
char *p;

Coptind = 1;            /* Required */
Copterr = 1;            /* Some stderr output if you want */

while ((c = Cgetopt(argc, argv, "0123456789")) != -1)
	switch (c) {
	case '0': case '1': case '2': case '3': case '4':
	case '5': case '6': case '7': case '8': case '9':
		p = argv[Coptind - 1];
		if (p[0] == '-' && p[1] == ch && !p[2])
			length = atoi(++p);
		else
			length = atoi(argv[Coptind] + 1);
		break;
	}
}
.ft
.LP
.fi
.P
The 
.B OPTIONAL_ARGUMENT
always eats the following argument unless the argument is included via the 
.B --option=argument 
notation.
.SH AUTHOR
Copyright (c) 1988, 1991, 1993 The Regents of the University of California.  All rights reserved.
.br
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
.br
1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
.br
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.
.br
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.
.br
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.
.br
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.