Linux Administration Handbook, Second Edition

4.13. Exercises

E4.1

Explain the relationship between a file’s UID and a running process’s real UID and effective UID. Besides file access control, what is the purpose of a process’s effective UID?

E4.2

Suppose that a user at your site has started a long-running process that is consuming a significant fraction of a machine’s resources. a. How would you recognize a process that is hogging resources? b. Assume that the misbehaving process might be legitimate and doesn’t deserve to die. Show the commands you would use to put it “on ice” (stop it temporarily while you investigate). c. Later, you discover that the process belongs to your boss and must continue running. Show the commands you would use to resume the task. d. Alternatively, ...