GETSUBOPT(3)                   Library Routines                   GETSUBOPT(3)

NAME

       getsubopt - get sub options from an argument

SYNOPSIS

       #include <stdlib.h>

       extern char *suboptarg;

       int getsubopt (char **optionp, char * const *tokens, char **valuep);

DESCRIPTION

       The  getsubopt  function parses a string containing tokens delimited by
       one or more tab, space or comma characters.  It is intended for use  in
       parsing  groups  of option arguments provided as part of a utility com‐
       mand line.

       The argument optionp is a pointer to a pointer to the string.  The  ar‐
       gument  tokens is a pointer to a NULLNs-terminated array of pointers to
       strings.

       The getsubopt function returns the zero-based offset of the pointer  in
       the  tokens array referencing a string which matches the first token in
       the string, or, -1 if the string contains no tokens or tokens does  not
       contain a matching string.

       If  the token is of the form ``name=value'', the location referenced by
       valuep will be set to point to the start of the  ``value''  portion  of
       the token.

       On  return from getsubopt, 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 suboptarg will be
       set to point to the start of the current token, or NULL  if  no  tokens
       were  present.   The  argument  valuep  will  be  set  to  point to the
       ``value'' portion of the token, or NULL if  no  ``value''  portion  was
       present.

EXAMPLE

       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;
            }

SEE ALSO

       getopt(3), strsep(3)

HISTORY

       The getsubopt function first appeared in 4.4BSD.



GNO                            22 February 1997                   GETSUBOPT(3)