[Linux] Bash shutdown uso: Shut down or restart the system

Overview

The shutdown command is used to safely turn off or restart a Linux system. It allows users to schedule shutdowns, notify logged-in users, and specify the reason for the shutdown.

Usage

The basic syntax of the shutdown command is as follows:

shutdown [options] [time] [message]

Common Options

• -h or --halt: Halts the system after shutdown.
• -r or --reboot: Reboots the system after shutdown.
• -P or --poweroff: Powers off the machine after shutdown.
• -c: Cancels a scheduled shutdown.
• time: Specifies when to shut down (e.g., now, +5 for five minutes later, or a specific time like 23:00).
• message: An optional message to display to users before shutdown.

Common Examples

1. Shut down immediately:

   shutdown now
   

2. Shut down after 10 minutes:

   shutdown +10
   

3. Reboot the system immediately:

   shutdown -r now
   

4. Power off the system at a specific time (e.g., 11:30 PM):

   shutdown 23:30
   

5. Cancel a scheduled shutdown:

   shutdown -c
   

6. Shut down with a custom message:

   shutdown +5 "System will shut down in 5 minutes for maintenance."
   

Tips

• Always notify users before shutting down the system, especially on multi-user systems, to prevent data loss.
• Use the -c option to cancel a shutdown if you change your mind.
• Schedule shutdowns during off-peak hours to minimize disruption.
• Consider using shutdown -h for a complete halt or shutdown -r for a reboot, depending on your needs.