Service Control

Question 1

What is the purpose of service control?

Answer 1

Manage and monitor background services; start, stop, restart, or reload services using systemctl; check service state for troubleshooting and performance.

Question 2

What does systemctl status do?

Answer 2

Displays current state and service details.

Question 3

What is the syntax for checking service status?

Answer 3

systemctl status <service-name></service-name>

Question 4

Give an example of checking cron service status.

Answer 4

systemctl status cron.service

Question 5

What information does systemctl status output include?

Answer 5

Service description and loaded status; active state and uptime; main PID and memory usage; CGroup and process tree.

Question 6

Why is systemctl status useful?

Answer 6

Used to identify running, inactive, or failed services.

Question 7

What does systemctl start do?

Answer 7

Starts a service immediately; does not enable service at boot.

Question 8

What is the syntax for starting a service?

Answer 8

sudo systemctl start <service-name></service-name>

Question 9

Give an example of starting Apache service.

Answer 9

sudo systemctl start apache2.service

Question 10

How to confirm a service started successfully?

Answer 10

Run systemctl status <service-name>.</service-name>

Question 11

What does systemctl restart do?

Answer 11

Stops and starts a service in one command; used after configuration changes or to clear errors.

Question 12

What is the syntax for restarting a service?

Answer 12

sudo systemctl restart <service-name></service-name>

Question 13

Give an example of restarting UFW service.

Answer 13

sudo systemctl restart ufw.service

Question 14

What output is shown when restarting a service?

Answer 14

No output if successful; status command confirms results.

Question 15

What does systemctl reload do?

Answer 15

Reloads service configuration without stopping the service; works only if service supports dynamic reloads.

Question 16

What is the syntax for reloading a service?

Answer 16

sudo systemctl reload <service-name></service-name>

Question 17

Give an example of reloading Postfix service.

Answer 17

sudo systemctl reload postfix.service

Question 18

What happens if reload is unsupported?

Answer 18

Systemd returns an error; restart is an alternative for live updates.