Automate Background Tasks with Linux Service and Timer

What is a Linux Service? It is a program that runs in the background without user interaction. It usually stays running even after a computer reboot. An example is daily backing up a database from a production server. You run a task in the background that dumps the whole database and saves it to a computer.

For example, I will empty the trash on an Ubuntu desktop every minute.

Create a bash script to empty the trash, name it empty-trash.sh, save it in /opt.

#!/bin/bash

rm -rf /home/<username>/.local/share/Trash/*

Make it executable.

sudo chmod +x /opt/empty-trash.sh

Create the service file empty-trash.service in /etc/systemd/system as root.

sudo touch /etc/systemd/system/empty-trash.service

Next is to copy and paste this to the empty-trash.service file.

[Unit]
Description=Empty trash every minute

[Service]
ExecStart=bash /opt/empty-trash.sh
User=<username>

[Install]
WantedBy=multi-user.target

• The [Unit] section holds the description of the service file.
• The [Service] section tells how the service should run
  • ExecStart directive is where we specify the command that we want to run which is the bash /opt/empty-trash.sh.
  • The User directive specifies the account under which the script will execute.
• The [Install] section defines how systemd should manage the service during system startup or when it is enabled.
  • WantedBy with a value of multi-user.target means it will be linked to the system’s boot process.

Create a timer file empty-trash.timer in /etc/systemd/system as root.

sudo touch /etc/systemd/system/empty-trash.timer

Next is to copy and paste this to the empty-trash.timer file.

[Unit]
Description=Run empty-trash service every minute

[Timer]
OnUnitActiveSec=1min
Persistent=true

[Install]
WantedBy=timers.target

• The [Unit] section holds the description of the timer file.
• The [Timer] section holds the configuration of the scheduling of the timer
  • OnUnitActiveSec directive means that the timer will trigger on the scheduled time
  • Persistent=true means the timer will compensate for the missed schedule if the system is powered off.
• The [Install] section specifies how the timer will connect to the system
  • WantedBy=timers.target means the timer will be added to timers.target. timers.target organizes and starts all timers.

To modify the time, change the value of OnUnitActiveSec.

Run the command below to let the system know of a new service:

sudo systemctl daemon-reload

Run the commands below to start the services:

sudo systemctl start empty-trash.service
sudo systemctl start empty-trash.timer

Run the commands below if you want it to enable the service at startup:

sudo systemctl enable empty-trash.service
sudo systemctl enable empty-trash.timer

Run the commands below if you want to check the status:

sudo systemctl status empty-trash.service
sudo systemctl status empty-trash.timer

Run the commands below if you want to stop the services:

sudo systemctl stop empty-trash.service
sudo systemctl stop empty-trash.timer

Now, you can check the trash from time to time to see if it empties.

Github Gist: https://gist.github.com/rinavillaruz/eb4b5230d5bb0fbded2e916ad0ca189c