shutdown

Overview

The shutdown command brings the system down in a secure way. It notifies users, stops processes gracefully, and either halts, powers off, or reboots the system.

Syntax

shutdown [options] [time] [message]

Common Options

Option Description
-h Halt or power off
-r Reboot
-c Cancel pending shutdown
-k Only send warning
-P Power off
-H Halt
-f Force fsck on reboot
-F Skip fsck on reboot
now Immediate shutdown
+m Minutes to wait
HH:MM Specific time

Key Use Cases

  1. System maintenance
  2. Emergency shutdown
  3. Scheduled reboots
  4. Power management
  5. User notification

Examples with Explanations

Example 1: Immediate Shutdown

shutdown -h now

Halt system immediately

Example 2: Scheduled Reboot

shutdown -r +15 "System maintenance in 15 minutes"

Reboot in 15 minutes with message

Example 3: Cancel Shutdown

shutdown -c

Cancel pending shutdown

Understanding Output

System messages: - Broadcast warning - Process termination - Service shutdown - Final system state

Common Usage Patterns

  1. Power off:

    shutdown -P now

  2. Delayed shutdown:

    shutdown -h +30

  3. Specific time:

    shutdown -r 23:00

Security Considerations

  1. User permissions
  2. Process termination
  3. Data integrity
  4. Service shutdown
  5. Network connections

Additional Resources

Best Practices

  1. Notify users
  2. Schedule maintenance
  3. Check active processes
  4. Verify file systems
  5. Document actions

Process Handling

  1. SIGTERM signals
  2. Service shutdown
  3. Process cleanup
  4. File system sync
  5. Hardware shutdown

Safety Checks

  1. Active users
  2. Running processes
  3. Open files
  4. Network connections
  5. System services