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    Command:

    getsubopt

    
    
    

    SYNOPSIS

           #include <stdlib.h>
    
           int getsubopt(char **optionp, char * const *tokens, char **valuep);
    
       Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
    
           getsubopt():
               _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
               || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
    
    
    

    DESCRIPTION

           getsubopt()  parses  the list of comma-separated suboptions provided in
           optionp.  (Such a suboption list is typically produced  when  getopt(3)
           is  used  to  parse  a  command  line; see for example the -o option of
           mount(8).)  Each suboption may include an associated  value,  which  is
           separated  from  the suboption name by an equal sign.  The following is
           an example of the kind of string that might be passed in optionp:
    
               ro,name=xyz
    
           The tokens argument is a pointer to a NULL-terminated array of pointers
           to  the  tokens  that getsubopt() will look for in optionp.  The tokens
           should be distinct, null-terminated strings  containing  at  least  one
           character, with no embedded equal signs or commas.
    
           Each call to getsubopt() returns information about the next unprocessed
           suboption in optionp.  The first equal sign in a suboption (if any)  is
           interpreted  as a separator between the name and the value of that sub-
           option.  The value extends to the next comma, or (for the  last  subop-
           tion) to the end of the string.  If the name of the suboption matches a
           known name from tokens, and a value string was found, getsubopt()  sets
           *valuep  to  the address of that string.  The first comma in optionp is
           overwritten with a null  byte,  so  *valuep  is  precisely  the  "value
           string" for that suboption.
    
           If  the suboption is recognized, but no value string was found, *valuep
           is set to NULL.
    
           When getsubopt() returns, optionp points to the next suboption,  or  to
           the null byte ('\0') at the end of the string if the last suboption was
           just processed.
    
    
    

    RETURN VALUE

           If the first suboption in optionp is  recognized,  getsubopt()  returns
           the  index  of the matching suboption element in tokens.  Otherwise, -1
           is returned and *valuep is the entire name[=value] string.
    
           Since *optionp is changed, the first suboption before the call to  get-
           subopt()  is  not  (necessarily)  the same as the first suboption after
           getsubopt().
    
    
           int
           main(int argc, char **argv)
           {
               enum {
                   RO_OPT = 0,
                   RW_OPT,
                   NAME_OPT
               };
               char *const token[] = {
                   [RO_OPT]   = "ro",
                   [RW_OPT]   = "rw",
                   [NAME_OPT] = "name",
                   NULL
               };
               char *subopts;
               char *value;
               int opt;
    
               int readonly = 0;
               int readwrite = 0;
               char *name = NULL;
               int errfnd = 0;
    
               while ((opt = getopt(argc, argv, "o:")) != -1) {
                   switch (opt) {
                   case 'o':
                       subopts = optarg;
                       while (*subopts != '\0' && !errfnd) {
    
                       switch (getsubopt(&subopts, token, &value)) {
                       case RO_OPT:
                           readonly = 1;
                           break;
    
                       case RW_OPT:
                           readwrite = 1;
                           break;
    
                       case NAME_OPT:
                           if (value == NULL) {
                               fprintf(stderr, "Missing value for "
                                       "suboption '%s'\n", token[NAME_OPT]);
                               errfnd = 1;
                               continue;
                           }
    
                           name = value;
                           break;
    
                       default:
                           fprintf(stderr, "No match found "
    
                   }
               }
    
               if (errfnd || argc == 1) {
                   fprintf(stderr, "\nUsage: %s -o <suboptstring>\n", argv[0]);
                   fprintf(stderr, "suboptions are 'ro', 'rw', "
                           "and 'name=<value>'\n");
                   exit(EXIT_FAILURE);
               }
    
               /* Remainder of program... */
    
               exit(EXIT_SUCCESS);
           }
    
    
    

    SEE ALSO

           getopt(3)
    
    
    

    GNU 2010-09-26 GETSUBOPT(3)

    
    
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