Run Multiple Bash Scripts with Systemd (Step-by-Step)

This tutorial guides you through setting up a systemd service to efficiently run multiple Linux Bash scripts. You’ll learn how to create a service that automatically starts, stops, and restarts your scripts. Let’s dive in!

Prerequisites

Linux System: You need a Linux system (e.g., Ubuntu, CentOS, Debian) with systemd installed.
Bash Scripts: Prepare the Bash scripts you want to run. Ensure they are executable and located in a specific directory (e.g., /path-to-bash-script/).

Steps to Create the Systemd Service

Create a Template Unit File:

Decide how many script instances you need (e.g., three instances).

Create a template unit file (e.g., /etc/systemd/system/foo@.service). Note the ”@” symbol, which allows for parameterization.

Add the following content to the file, replacing placeholders with your information:

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[Unit]
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Description=Running Bash Script for %I
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[Service]
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Type=simple
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ExecStart=/bin/bash /path-to-bash-script/script-name-%i.sh
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ExecStop=/bin/bash /path-to-bash-script/script-name-%i.sh
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Restart=on-failure
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[Install]
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WantedBy=foo.target

%I represents the instance identifier passed during service activation.
%i represents the instance identifier converted to lowercase.

Replace /path-to-bash-script/ and script-name- with your actual paths and script name prefixes.

Enable Instances:

Enable the desired number of instances using systemctl enable:

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systemctl enable foo@{1..3}.service

This command creates symlinks for instances foo@1.service, foo@2.service, and foo@3.service based on the template.

Start the Instances:

Start individual instances with systemctl start, providing the instance identifier:

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systemctl start foo@1.service
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systemctl start foo@2.service
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systemctl start foo@3.service

Create a Target Dependency:

To group instances under a common target for easier management, create a target unit file (e.g., /etc/systemd/system/foo.target):

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[Unit]
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Description=foo target
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Requires=multi-user.target
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After=multi-user.target
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AllowIsolate=yes

Modify your .service units to be WantedBy=foo.target.

Reload and Start:

Reload systemd to apply changes:

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sudo systemctl daemon-reload

Start the target (if created):

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sudo systemctl start foo.target

Testing the Service

To test an instance, run:

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sudo systemctl start foo@1.service

Check the status:

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sudo systemctl status foo@1.service

If everything is configured correctly, you’ll see the output of your Bash script.

Conclusion

Congratulations! You’ve successfully set up a systemd service to manage multiple Bash script instances. This approach provides a structured way to automate and control your scripts.

Remember to adapt the paths, filenames, and instance numbers to your specific needs. Happy scripting! 🚀🐧