char buf[1024];
// You can stick together "strings" "like" "this" to get "stringslikethis" which lets you 
// seperate one string across lines, like I'm doing with the two echo commands.
sprintf(buf, "echo '%s' ;"
             "echo '%s'",
        "string 1 which must not contain quote characters",
        "string 2 which must not contain quote characters");

fprintf(stderr, "calling system('%s')\n", buf);
system(buf);