linuxexpert-practice-labs/labs/linux-plus/2-3-2-signals-jobs-priority/README.md

Linux+ 2.3.2: Signals, jobs and priority

Sending signals by name and pattern without hitting the wrong process, and changing a running process's priority.

Before you start

The lab creates user alice (password Lab-Pass-1) and starts three of her processes: sleep 1000, sleep 1001, and yes running at nice 15. The chapter's job control (step 1) and ulimit (step 4) steps work in your own shell and aren't graded; try them anyway.

Tasks

1. Look at alice's sleep processes with pgrep -a. Stop sleep 1000 with a signal, and leave sleep 1001 running. (pkill -f 'sleep 100' would match both.)
2. Lower the priority of alice's yes process to nice 19. Then, as alice, try to set it back to 0 and see that it's refused.

Hints

• pgrep -a sleep, pgrep -fx 'sleep 1000', kill PID, pkill -x/-f with an anchored pattern such as '^sleep 1000$'.
• ps -o pid,ni,%cpu,cmd -p PID, renice -n 19 -p PID; su - alice.