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+.\" $OpenBSD: getsubopt.3,v 1.7 2003/06/02 20:18:37 millert Exp $
+.\"
+.\" Copyright (c) 1990, 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.
+.\"
+.\"     @(#)getsubopt.3 8.1 (Berkeley) 6/9/93
+.\"
+.Dd June 9, 1993
+.Dt GETSUBOPT 3
+.Os
+.Sh NAME
+.Nm getsubopt
+.Nd get sub options from an argument
+.Sh SYNOPSIS
+.Fd #include <stdlib.h>
+.Vt extern char *suboptarg;
+.Ft int
+.Fn getsubopt "char **optionp" "char * const *tokens" "char **valuep"
+.Sh DESCRIPTION
+The
+.Fn getsubopt
+function parses a string containing tokens delimited by one or more
+tab, space or comma
+.Pq Ql \&,
+characters.
+It is intended for use in parsing groups of option arguments provided
+as part of a utility command line.
+.Pp
+The argument
+.Fa optionp
+is a pointer to a pointer to the string.
+The argument
+.Fa tokens
+is a pointer to a null-terminated array of pointers to strings.
+.Pp
+The
+.Fn getsubopt
+function returns the zero-based offset of the pointer in the
+.Fa tokens
+array referencing a string which matches the first token
+in the string, or \-1 if the string contains no tokens or
+.Fa tokens
+does not contain a matching string.
+.Pp
+If the token is of the form
+.Ar name Ns No = Ns Ar value ,
+the location referenced by
+.Fa valuep
+will be set to point to the start of the
+.Dq value
+portion of the token.
+.Pp
+On return from
+.Fn getsubopt ,
+.Fa optionp
+will be set to point to the start of the next token in the string,
+or the null at the end of the string if no more tokens are present.
+The external variable
+.Fa suboptarg
+will be set to point to the start of the current token, or
+.Dv NULL
+if no tokens were present.
+The argument
+.Fa valuep
+will be set to point to the value portion of the token, or
+.Dv NULL
+if no value portion was present.
+.Sh EXAMPLES
+.Bd -literal -compact
+char *tokens[] = {
+        #define ONE     0
+                "one",
+        #define TWO     1
+                "two",
+        NULL
+};
+
+\&...
+
+extern char *optarg, *suboptarg;
+char *options, *value;
+
+while ((ch = getopt(argc, argv, "ab:")) != \-1) {
+        switch(ch) {
+        case 'a':
+                /* process ``a'' option */
+                break;
+        case 'b':
+                options = optarg;
+                while (*options) {
+                        switch(getsubopt(&options, tokens, &value)) {
+                        case ONE:
+                                /* process ``one'' sub option */
+                                break;
+                        case TWO:
+                                /* process ``two'' sub option */
+                                if (!value)
+                                        error("no value for two");
+                                i = atoi(value);
+                                break;
+                        case \-1:
+                                if (suboptarg)
+                                        error("illegal sub option %s",
+                                          suboptarg);
+                                else
+                                        error("missing sub option");
+                                break;
+                }
+                break;
+        }
+.Ed
+.Sh SEE ALSO
+.Xr getopt 3 ,
+.Xr strsep 3
+.Sh HISTORY
+The
+.Fn getsubopt
+function first appeared in
+.Bx 4.4 .