This example shows how to create a unit file for a custom service. Custom unit files are located in `/etc/systemd/system/` and have a `.service` extension. For example, a custom `foo` service uses `/etc/systemd/system/foo.service` unit file.
.Prerequisites
* You are logged in as a user with administrator-level permissions.
.Procedure
This procedure creates a basic configuration file to control the `foo` service.
. The next few steps describe each section its parameters to add to the file:
.. The `[Unit]` section provides basic information about the service. The `foo` service uses the following parameters:
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`Description`::
A string describing the unit. Systemd displays this description next to the unit name in the user interface.
`Requires`::
Defines unit to use as a dependency for the service. If you activate the unit, Systemd activates the units listed in `Requires` as well. For example, the `foo` service might require network connectivity, which means the `foo` services requires `network.target` as a dependency.
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The resulting `[Unit]` section looks like this:
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----
[Unit]
Description=My custom service
Requires=network.target
----
.. The `[Service]` section provides instructions on how to control the service. The `foo` service uses the following parameters:
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`Type`::
Defines the type of Systemd service. In this example, the `foo` service is a `simple` service, which starts the service without any special consideration.
`ExecStart`::
The command to run to start the service. This includes the full path to the command and arguments to modify the service.
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The resulting `[Service]` section looks like this:
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----
[Service]
Type=simple
ExecStart=/usr/bin/sleep infinity
----
.. The `[Install]` section provides instructions on how Systemd installs the service. The `foo` service uses the following parameters:
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`WantedBy`::
Defines which service triggers the custom service if enabled with `systemctl enable`. This is mostly used for starting the custom service on boot. In this example, `foo.service` uses `multi-user.target`, which starts `foo.service` when Systemd loads `multi-user.target` on boot.
. The full `foo.service` file contains the following contents: