When is it OK to pass NULLs to the 2nd and 3rd args of execve()?

[Peng Yu <pengyu.ut@gmail.com>]

Hi,

I am wondering when (all possible legitimate cases) it is OK to pass
NULLs to execve's 2nd and 3rd args.

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

int main(int argc, char *argv[]) {
	if(execve(argv[1], NULL, NULL) == -1) {
		perror("execvp()");
		return 1;
	}
	return 0;
}


I tried the above program. It works when it is called with `/bin/sh`.
My guess is that when the program being exec'ed don't use its args and
envs, then then 2nd and 3rd args of execve() can be NULLs. Could
anybody correct me if I am wrong?

-- 
Regards,
Peng