LCA Process Management & System Services

Question 1

Which command displays all running processes in a hierarchical tree format showing parent-child relationships?

Accepted Answer

pstree

Answer

ps aux

Answer

top

Answer

htop

Question 2

What signal number is used to forcefully terminate a process, bypassing any cleanup handlers?

Accepted Answer

9 (SIGKILL)

Answer

1 (SIGHUP)

Answer

15 (SIGTERM)

Answer

18 (SIGCONT)

Question 3

Which systemctl command enables a service to start automatically at system boot?

Accepted Answer

systemctl enable

Answer

systemctl start

Answer

systemctl activate

Answer

systemctl boot

Question 4

What is the effect of running a process with a higher nice value such as 'nice +19'?

Accepted Answer

The process receives lower CPU scheduling priority

Answer

The process receives higher CPU scheduling priority

Answer

The process runs in the background automatically

Answer

The process becomes immune to termination signals

Question 5

Which file is the system-wide crontab that includes a username field for specifying which user runs each job?

Accepted Answer

/etc/crontab

Answer

/etc/cron.d/root

Answer

/var/spool/cron/root

Answer

/etc/cron.allow

Question 6

Which command shows the current runtime status, recent log entries, and PID of a systemd-managed service?

Accepted Answer

systemctl status

Answer

systemctl info

Answer

systemctl show

Answer

systemctl inspect

Question 7

Which command sends a signal to all processes matching a given name without requiring the PID?

Accepted Answer

pkill

Answer

kill

Answer

killall -n

Answer

sigkill