getopt does not parse optional arguments to parameters

Question

In C, getopt_long does not parse the optional arguments to command line parameters parameters.

When I run the program, the optional argument is not recognized like the example run below.

$ ./respond --praise John Kudos to John $ ./respond --blame John You suck ! $ ./respond --blame You suck ! 

Here is the test code.

#include <stdio.h> #include <getopt.h>  int main(int argc, char ** argv ) {     int getopt_ret, option_index;     static struct option long_options[] = {                {"praise",  required_argument, 0, 'p'},                {"blame",  optional_argument, 0, 'b'},                {0, 0, 0, 0}       };     while (1) {         getopt_ret = getopt_long( argc, argv, "p:b::",                                   long_options,  &option_index);         if (getopt_ret == -1) break;          switch(getopt_ret)         {             case 0: break;             case 'p':                 printf("Kudos to %s\n", optarg); break;             case 'b':                 printf("You suck ");                 if (optarg)                     printf (", %s!\n", optarg);                 else                     printf ("!\n", optarg);                 break;             case '?':                 printf("Unknown option\n"); break;         }     }      return 0; } 

Answer 1

Although not mentioned in glibc documentation or getopt man page, optional arguments to long style command line parameters require 'equals sign' (=). Space separating the optional argument from the parameter does not work.

An example run with the test code:

$ ./respond --praise John Kudos to John $ ./respond --praise=John Kudos to John $ ./respond --blame John You suck ! $ ./respond --blame=John You suck , John!