LFCS Certification Process and Job Scheduling 2

Question 1

Which command sends a SIGSTOP signal to suspend a running process with PID 1234?

Accepted Answer

kill -STOP 1234

Answer

SIGSTOP (signal 19) pauses a process; it cannot be caught or ignored, unlike SIGTSTP sent by Ctrl+Z.

Question 2

What does the `renice` command do in Linux?

Accepted Answer

Changes the priority of an already-running process

Answer

`renice` alters the scheduling priority of one or more running processes without restarting them.

Question 3

A systemd timer unit is configured with `OnCalendar=daily`. What does this mean?

Accepted Answer

The associated service runs once every 24 hours at midnight

Answer

`OnCalendar=daily` is equivalent to `*-*-* 00:00:00`, triggering the service at midnight each day.

Question 4

Which file would you edit to schedule a cron job that runs as the `www-data` user?

Accepted Answer

/etc/cron.d/myjob

Answer

Files in `/etc/cron.d/` support a username field, allowing jobs to run as a specific user like `www-data`.

Question 5

What is the output of `ps aux` showing in the STAT column value `Z`?

Accepted Answer

A zombie process that has finished but not been reaped

Answer

A 'Z' (zombie) process has exited but its parent has not yet called `wait()` to collect its exit status.

LFCS Certification Practice Test