====== Ubuntu - Systemd - Wants ======

If you want service B to start when service A starts, you can use the **Wants** parameter to make it happen.

  * In the **[Unit]** section of a systemd .service file, add a line like this:

<file bash>
[Unit]
Wants = b.service
</file>

You can also use Before = or After = to specify the order.

<file bash>
[Unit]
Wants = b.service
Before = b.service
</file>

Sometimes, you may want service B to wait for service A to complete before starting itself.

  * Then you can add the following lines in the [Service] section of the b.service file.

<file bash>
[Service]
ExecStartPre=/bin/sleep 20
</file>

<WRAP info>
**NOTE:**  This tells b.service to wait 20 seconds.
</WRAP>

----

===== Reload systemd =====

Remember to reload systemd for the changes to take effect.

<code bash>
sudo systemctl daemon-reload
</code>