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

pstree displays processes in a tree structure that clearly shows parent-child relationships between processes.

Question 2

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

Accepted Answer

9 (SIGKILL)

Answer

SIGKILL (signal 9) immediately terminates a process at the kernel level without allowing the process to perform any cleanup.

Question 3

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

Accepted Answer

systemctl enable

Answer

systemctl enable creates the necessary symlinks so the service is started during the appropriate boot target automatically.

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

Higher nice values (up to +19) indicate lower scheduling priority, meaning the process yields CPU time to other processes.

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/crontab is the system-wide crontab file with an extra username field, distinguishing it from per-user crontabs.

(LCA) Certified Linux Administrator Practice Test