3.5 System Shutdown

Question 2

What happens when you run init 0 at the shell?

Answer 2

The system shuts down immediately.

Question 3

How would you send a message to all users on the system without shutting down the system?

Answer 3

Use the shutdown -k message command.

Question 4

Which commands shut the system down immediately?

Answer 4

The commands shutdown -h now, init 0, and halt all shut the system down immediately.

Question 5

What command will reboot the system after 15 minutes?

Answer 5

The comand shutdown -r +15 will reboot the system after 15 minutes.

Question 6

What is the purpose of the /etc/shutdown.allow?

Answer 6

The /etc/shutdown.allow command determines who is allowed to shut the system down when using the shutdown -a command.

Question 7

How can you terminate the shutdown process after it is already running?

Answer 7

The keyboard sequence Ctrl-C and the command shutdown -c both terminate the shutdown process.

Question 8

What does the command shutdown -h now do?

Answer 8

Shuts the system down immediately.

• -h specifies that the system halt or poweroff after shutdown.
• now forces the system to shut down without a delay.

Question 9

What does the command halt do?

Answer 9

Shuts the system down immediately.

Question 10

What does the command init 0 do?

Answer 10

Shuts the system down immediately.

Question 11

What does the command shutdown -r now do?

Answer 11

Shuts the system down immediately and reboots.

Question 12

What does the command reboot do?

Answer 12

Shuts the system down immediately and reboots.

Question 13

What does the command init 6 do?

Answer 13

Shuts the system down immediately and reboots.

Question 14

What does the command shutdown -h time message do?

Answer 14

Sends the specified message to all logged-in users and shuts the system down at the specified time.

Question 15

What does the command shutdown -r time message do?

Answer 15

Sends the specified message to all logged-in users and reboots the system at the specified time and sends the specified message to users.

Question 16

What does the command shutdown -h +5 System is going down do?

Answer 16

Sends the specified message to all logged-in users and shuts the system down in 5 minutes.

Question 17

What does the command shutdown -h 22:00 do?

Answer 17

Shuts the system down at 10:00 pm.

Question 18

What does the command shutdown -r +15 do?

Answer 18

Reboots the system in 15 minutes.

Question 19

What does the command shutdown -r 24:00 System is going down at Midnight do?

Answer 19

Sends the specified message to all logged-in users and reboots the system at midnight.

Question 20

What does the command shutdown -c do?

Answer 20

Terminates the shutdown process from any console.

Question 21

What does the keyboard sequence Ctrl+C do with regard to system shutdown?

Answer 21

Terminates the shutdown process in the constole from which the shutdown command was issued.

Question 22

What does the keyboard sequence shutdown -rf time do?

Answer 22

Reboots the system at the specified time and skips the fsck utility on reboot. The -f parameter stands for reboot fast.

Question 23

What does the command shutdown -rf do?

Answer 23

Reboots the system and skips fsck utility on reboot.

Question 24

What does the command shutdown -k message do?

Answer 24

Sends the specified message to all logged-in users but does not shut down the system down. If used in combination with -h or -r, it will terminate the shutdown process after the message is sent.

Question 25

What does the command shutdown -k Please log out of the system do?

Answer 25

Sends the specified message to all logged-in users but does not shut the system down.

Question 26

What does the command shutdown -a do?

Answer 26

Causes the system to consult the /etc/shutdown.allow prior to shutting down the system to determine whether or not the user is authorized to shutdown the system. This is typically used in the Ctrl-Alt-Delete section of the /etc/inittab file to control who can shutdown the system with this keyboard sequence.

Question 27

How is the file /etc/shutdown.allow used by the shutdown -a command?

Answer 27

• If a listed user or root is logged into the system, the system shuts down.
• If a listed user or root is not logged into the system, shutdown is not allowed.
• If the /etc/shutdown.allow file does not exist, there are no restrictions on who can shut down the system.