Question

I have the following code:

std::string cmd = "sudo chmod a+x file";
int r = system(cmd.c_str());

which works correctly.

How can I do the same thing without calling the system() function?

What I can get to is:

#include <sys/stat.h>
int r = chmod("file", S_IXUSR | S_IXGRP | S_IXOTH);

How can I use “sudo” in this case?

Thank you.

Answer 1

You can’t. Unless your program is suid root which is most likely not the case – otherwise you wouldn’t use sudo.

However, depending on what your program does, giving it setuid-root might indeed be the way to go. You need to perform operations that require root privileges and sudo access to chmod, especially on arbitrary modes/paths, is usually not granted to non-root users.