getopt in Mac OS X

Question

I need to parse arguments using the getopt function. The problem is if I have arguments before and/or after options, getopt doesn't work. Option processing stops as soon as a nonoption argument is encountered.

For exemple : tftp ip port [-b blksize] src dest doesn't work. But tftp [-b blksize] ip port src dest works well.

Apparently, I need to add + at the beginning of optstring to be able to mix arguments and options but it doesn't supported on Max OS X according to https://www.gnu.org/software/gnulib/manual/html_node/getopt.html

Have you a solution? Thanks.

Answer 1

Change what you pass getopt in as argv and argc to skip over the command portion.

For example, tftp ip port [-b blksize] src dest you'd pretend port at argv[2] is argv[0]. Call getopt(argc - 2, argv + 2, optstring).

#include <unistd.h>
#include <stdio.h>

int main(int argc, char *argv[]){
    int ch;

    while( (ch = getopt(argc - 2, argv + 2, "b:")) != -1 ) {
        printf("%c %s\n", ch, optarg);
    }

    return 0;
}

This is just an example. It's up to you to add the logic to determine if there is a command or subcommand.