Auto Launch Program on Boot

This guide will show you how to launch a program on boot in a Linux system using systemd, routine execution is also covered.

Problem

You want to automatically launch a program whenever your linux machine boots up.

Background

In linux system boot sequence, BIOS/UEFI gets loaded and executed, later it triggers the boot loader (ex: GRUB) which loaded the OS. Once the OS is loaded, it execute a service called "systemd" [1]. This service later starts all of the background processes necessary for modern day OS. In our case, we can use the ability to launch processes/services powered by systemd to achive our goal.

Linux Boot Process

Figure 1: Linux Boot Process [2]

Solution 1: systemd

Step 1: Create a Service File

In this step, let's create a service file that systemd can use to launch our program. After activated, the program launched by this service is considered as a daemon process.

Create a service file in path /lib/systemd/system/<service_name>.service, which can very depending on the Linux distribution you are using. This is proven to work on both Ubuntu and Raspbian.
```
sudo touch /lib/systemd/system/test_service.service
```

Open the file in a text editor and add the following content:

[Unit]
Description=This is a test service for demonstration
After=multi-user.target     # When the service should be started
StartLimitIntervalSec=0     # Interval to wait before restarting a service when it fails (return code is non-zero)

[Service]
User=<your_account_name>    # Which account to run the service under, if not specified, it will run under root
Type=simple                 # Type of service, simple is the most common option for one-off tasks
KillMode=mixed              # How to kill the service, mixed is used to kill all associated processes (including child processes)
#TimeoutSec=60              # How long to wait before considering the service as failed and killing it, now disabled, set to 60 seconds
#ExecStartPre=/bin/sleep 5  # Command to run before the main command, now disabled, set to sleep for 5 seconds
ExecStart=/usr/bin/python3 /home/test.py    # Command to run, in this case, it is a python script

[Install]
WantedBy=multi-user.target  # Which case the service should be started, in this case, all account will trigger the service

If you want to know more about the options in the service file, you can search for them in various Linux documentation websites.

Step 2: Activate the Service

Make systemd reload the service files.
```
sudo systemctl daemon-reload
```
Enable the service to start on boot. Change following command to your service name.
```
sudo systemctl enable test_service.service
```

Start the service now.

sudo systemctl start test_service.service

Check the status of the service.

sudo systemctl status test_service.service

(optional) Check the log of the service.

sudo journalctl -u test_service.service

(optional) Stop the service.

sudo systemctl stop test_service.service

(optional) Disable the service from starting on boot.
```
sudo systemctl disable test_service.service
```

Step 3: (optional) Routine Execution

In this step, let's create a timer service that will routinely trigger our service, which in turn will launch our program.

Create a service file in path /lib/systemd/system/<service_name>.timer, which can very depending on the Linux distribution you are using. This is proven to work on both Ubuntu and Raspbian.
```
sudo touch /lib/systemd/system/test_service.timer
```

Open the file in a text editor and add the following content:

[Unit]
Description=This is a test service for demonstration

[Service]
OnCalendar=hourly           # How often to trigger the service, in this case, hourly
#OnBootSec=1m               # How long to wait before triggering the service after boot, now disabled, set to 1 minute
#OnUnitActiveSec=1m         # How long to wait before re-triggering the service after previous launch, now disabled, set to 1 minute
Unit=test_service.service   # Which service to trigger
RemainAfterElapse=no        # Whether to keep this timer service active after it triggers the target service

[Install]
WantedBy=timers.target      # Which case the service should be started, in this case, by timers.target

Follow the same steps as in Step 2 to activate the timer service.

Step 4: (optional) Write a Script to Automatically Finish All the Steps

You can modify the following script to your needs while following the Provided License.

schedule_routine.sh: This is another script that will setup a update_task.timer to routinely trigger the update_task.sh to execute a custom script update_task.sh after system boot.

Solution 2: Desktop Entry

This solution is preferred for GUI applications, as it will launch the application in the user's desktop environment. Also, it is a lot easier to setup compared to systemd.

Step 1: Create a Desktop Entry File

Create a desktop entry file in path $HOME/.config/autosart/<app_name>.desktop:
```
touch $HOME/.config/autostart/test.desktop
```

Open the file in a text editor and add the following content:

[Desktop Entry]
Type=Application
Version=1.0
Name=Test
Comment=This is a test entry to launch a script on boot
Exec=/bin/bash /opt/boot_trigger.sh
StartupNotify=false
Terminal=true               # This is set to true to launch the script in a terminal window

Create the script that you want to launch in path /opt/boot_trigger.sh:

touch /opt/boot_trigger.sh
echo -e "\
#!/bin/bash\n\
gnome-terminal\n\
sleep infinity # This is to keep the original terminal open for debugging\n\
" > /opt/boot_trigger.sh

Next time you boot up your system, you will see a terminal window pop up automatically.

Step 2: (optional) Write a Script to Automatically Finish the Step

You can modify the following script to your needs while following the Provided License.

schedule_startup.sh: This is a script that will setup a update_task.service to execute a custom script update_task.sh after system boot.

References

Error Correction

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