dh_systemd_enable man page
dh_systemd_enable — enable/disable systemd unit files
dh_systemd_enable [debhelper options] [--no-enable] [--name=name] [unit file ...]
dh_systemd_enable is a debhelper program that is responsible for enabling and disabling systemd unit files.
In the simple case, it finds all unit files installed by a package (e.g. bacula-fd.service) and enables them. It is not necessary that the machine actually runs systemd during package installation time, enabling happens on all machines in order to be able to switch from sysvinit to systemd and back.
In the complex case, you can call dh_systemd_enable and dh_systemd_start manually (by overwriting the debian/rules targets) and specify flags per unit file. An example is colord, which ships colord.service, a dbus-activated service without an [Install] section. This service file cannot be enabled or disabled (a state called "static" by systemd) because it has no [Install] section. Therefore, running dh_systemd_enable does not make sense.
For only generating blocks for specific service files, you need to pass them as arguments, e.g. dh_systemd_enable quota.service and dh_systemd_enable --name=quotarpc quotarpc.service.
If this exists, it is installed into lib/systemd/system/package.service in the package build directory.
If this exists, it is installed into usr/lib/tmpfiles.d/package.conf in the package build directory. (The tmpfiles.d mechanism is currently only used by systemd.)
Disable the service(s) on purge, but do not enable them on install.
Note that this option does not affect whether the services are started. That is controlled by dh_systemd_start(1) (using e.g. its --no-start option).
Install the service file as name.service instead of the default filename, which is the package.service. When this parameter is used, dh_systemd_enable looks for and installs files named debian/package.name.service instead of the usual debian/package.service.
Note that this command is not idempotent. dh_prep(1) should be called between invocations of this command (with the same arguments). Otherwise, it may cause multiple instances of the same text to be added to maintainer scripts.
Note that dh_systemd_enable should be run before dh_installinit. The default sequence in dh does the right thing, this note is only relevant when you are calling dh_systemd_enable manually.