getopt does not parse optional arguments to parameters
arguments, c, getopt, getopt-long, optional-arguments
Solution
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!
Problem
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; } ```