How to Run a Program Automatically on Startup in Linux

If you want a program or script to run when the system starts up, then this can be done using systemctl. This method is universal: autorun also works on headless servers, not just when you enter a graphical desktop environment. This method is universal and will work on all systems where systemctl is present (e.g. Debian, Linux Mint, Ubuntu, Kali Linux, Arch Linux, etc.).

To add a script to autoload in Linux, you need to create a specific file in the /etc/systemd/system/ directory. Choose your own file name. For example, I want to run a script on startup that contains several rules to hinder DOS attacks. This file is located at /root/firewall.sh

We start by assigning the correct permissions to the file:

chmod 755 /root/firewall.sh

Make sure the file has shebang #!/bin/bash (or whatever matches the contents of the file).

I create a file anti-dos.service (you can choose your own name):

vim /etc/systemd/system/anti-dos.service

Content of my file

[Unit]
Description=Initial anti-DOS protection.

[Service]
ExecStart=/root/firewall.sh

[Install]
WantedBy=multi-user.target

Here

• Description=Initial anti-DOS protection. - this is a description, replace the description with your own.
• ExecStart=/root/firewall.sh - full path to the file that I want to add to startup is specified.

Don't write something like “ExecStart=/bin/sh /path/to/script.sh” as that won't work. If you really want to specify an interpreter and a script, then use a construction like this:

/usr/bin/bash -c 'INTERPRETER /PATH/TO/SCRIPT'

For instance:

/usr/bin/bash -c 'php /root/bin/translator.php'

Example file using this construction

[Unit]
Description=Launch translator.
 
[Service]
ExecStart=/usr/bin/bash -c 'php /root/bin/translator.php'
 
[Install]
WantedBy=multi-user.target

• WantedBy=multi-user.target - means that autorun is made for all users.

To start the services in the current session (change the name anti-dos.service to the name of your file):

systemctl start anti-dos.service

To check the status of a service:

systemctl status anti-dos.service

To enable autostart, you need to do this (change the name anti-dos.service to the name of your file):

systemctl enable anti-dos.service

Creating a link says that adding to autostart worked:

Let's restart the server to check))

The screenshot above shows that everything worked properly. The fact that the process is shown as deceased, in my case, is normal. Since I added not a service to autostart, but a one-time script.

To make sure that the firewall settings are in effect, I type:

iptables --list

Yes, my firewall rules are there.

You can also find your autorun file in the list of everything added to startup:

systemctl list-unit-files

After editing files with the extension .service, for the changes to take effect, you need to run the command:

systemctl daemon-reload