getopt_long си

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

int
main(int argc, char **argv)
{
        int ch;
        int s_flag = 0;
        int c_flag = 0;

        while ((ch = getopt(argc, argv, "sc")) != -1)
                switch (ch) {
                case 's':
                        s_flag = 1;
                        break;
                case 'c':
                        c_flag = 1;
                        break;
                default:
                        break;
                }
        argc -= optind;
        argv += optind;

        if (!(s_flag ^ c_flag))
                errx(1, "No, man!");

        if (s_flag)
                warnx("Server");
        if (c_flag)
                warnx("Client");

        return 0;
}