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Smeterlink
Asked: 2021-04-30 16:17:53 +0800 CST

How to run a command BEFORE shutdown on Ubuntu 21.04

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I just want to run (as root) a command or script before each reboot/shutdown/poweroff on Ubuntu 21.04 (when I run the shutdown or poweroff commands, or using GNOME/KDE GUI options). I've tried putting the script inside /etc/init.d and making symlinks to /etc/rc6.d/ and /etc/rc0.d/ but doesn't work.

Wonder if there's such a line for sudo crontab -e.

shutdown

1 Answers

  1. You can do this by creating a service file, then reloading systemd. Here's how:

    1. Open Terminal (if it's not already open)

    2. Ensure the script that you want to run at shutdown is executable:

      chmod +x ~/scripts/pre-shutdown.sh

    3. Create a file in /etc/systemd/system for the shutdown service. For the sake of this example, I'll call my file nighty-night.service.

    4. Add the following lines to the .service file, modifying it as needed:

      [Unit]
Description=Pre-Shutdown Processes
DefaultDependencies=no
Before=shutdown.target reboot.target halt.target
# This works because it is installed in the target and will be
#   executed before the target state is entered
# Also consider kexec.target

[Service]
Type=oneshot
User=smeterlink
Group= smeterlink
ExecStart=/home/smeterlink/scripts/pre-shutdown.sh  # your path and filename

[Install]
WantedBy=halt.target reboot.target shutdown.target

    5. Restart the daemon:

      sudo systemctl daemon-reload

    That's all there is to it.

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