The shutdown command arranges for the system to be brought down in a safe way. All logged-in users are notified that the system is going down and within the last five minutes leading up to the shutdown, new logins are prevented.
shutdown [OPTIONS] TIME [MESSAGE]
Follow Along
The shutdown command requires administrative access, switch to the root account for this section using the following command. Use netlab123 as the password.
sysadmin@localhost:~$ su - Password: root@localhost:~#
root@localhost:~# shutdown now Broadcast message from sysadmin@localhost (/dev/pts/0) at 2:05 ... The system is going down for maintenance NOW!
Unlike other commands used to bring the system down, the shutdown command requires a time argument specifying when the shutdown should begin. Formats of this time argument can be the word now, a time of day in the format hh:mm or the number of minutes to delay in the format +minutes.
Consider This
The clock on our system may be set to a different timezone than the one in which you are located. To check the time in the terminal, use the date command. On our machines, the default format of the date command output is as follows:
weekday month day hour:minute:second UTC year
The letters UTC present in the output indicates that the time is being displayed as Universal Coordinated Time.
root@localhost:~# date Sat Oct 3 22:15:58 UTC 2020 root@localhost:~# shutdown 01:51 Broadcast message from sysadmin@localhost (/dev/pts/0) at 1:50 ... The system is going down for maintenance in 1 minute! Broadcast message from sysadmin@localhost (/dev/pts/0) at 1:51 ... The system is going down for maintenance NOW!
The shutdown command also has an optional message argument, indicating a message that will appear in the terminals of all users. For example:
root@localhost:~# shutdown +1 "Goodbye World!" Broadcast message from sysadmin@localhost (/dev/pts/0) at 3:07 ... The system is going down for maintenance in 1 minute! Goodbye World! shutdown: Unable to shutdown system root@localhost:~# Broadcast message from sysadmin@localhost (/dev/pts/0) at 3:08 ... The system is going down for maintenance NOW! Goodbye World!
