Systemd – run a script before system shutdown

Here systemd will execute /srv/app_shutdown_script.sh before the system reboots. Refer to the following steps.

1. Create a systemd Unit file with the following content.

# cat /etc/systemd/system/exec-before-shutdown.service
[Unit]
Description=Shutdown run script 
DefaultDependencies=no
Before=shutdown.target

[Service]
Type=oneshot
ExecStart=/srv/app_shutdown_script.sh
TimeoutStartSec=0

[Install]
WantedBy=shutdown.target

2. Here we instructed the Unit file to run the script /srv/app_shutdown_script.sh before shutdown.target.

$ cat /srv/app_shutdown_script.sh

#!/bin/bash
c=0
for i in {1..3}; do
    sleep 1m
    ((c++))
    echo ""
done

3. Reload the systemd configuration files.
      # systemctl daemon-reload

4. Enable the Unit to automatically start at next boot.
   # systemctl enable exec-before-shutdown.service

Now reboot the system and confirm.