11.7 Enabling, Disabling and Masking systemd Units

A newly installed Ubuntu system will include the base systemd service units but is unlikely to include all of the services that will eventually be needed by the system once it goes into a production environment. A basic Ubuntu installation, for example, will typically not include the packages necessary to run an Apache web server, a key element of which is the apache2.service unit.

The system administrator will resolve this problem by installing the necessary Apache packages using the following command:

# apt install apache2

Having configured the web server, the next task will be to check the status of the apache2 service unit to identify whether it was activated as part of the installation process:

# systemctl status apache2.service

● apache2.service - The Apache HTTP Server

   Loaded: loaded (/lib/systemd/system/apache2.service; enabled; vendor preset: enabled)

  Drop-In: /lib...