Run shell script from C program by calling fork and execl

I need to write a c program that uses the fork and excel system calls to run the shell script mode invoked like this: "./mode 644 ls -l" (that is the argumetns will always be 644 ls -l)

here's the mode script:

#!/bin/sh
octal="$1"
shift
find . -maxdepth 1 -perm $octal -exec $@ {} \;

here's my c program:

        int rv;
        rv = execl("mode","644","ls","-l");
        getchar();

I don't get how to use fork and excel really?

Homework?

yes:p
I really do learn from the responses so I don't feel too bad about asking

Be as that might, but for homework there's an extra forum set aside, with additional rules. Pay special attention to the red text at the bottom of the rules, and then repost there.