Question

The SUID for any file can be set by the administrator using ____

(a) chmod

(b) chmod u+s filename

(c) chmod s filename

(d) chmod us filename

I have been asked this question in an interview for job.

This intriguing question originated from Administrator Specific Commands and Privileges in section Essential Shell Programming of Unix

Answer 1

Correct option is (b) chmod u+s filename

To elaborate: The SUID (set-user-ID) lets a process have the privileges of the owner of the file during the instance of the program. The SUID for any file can be set by the administrator using chmod command. For example,