unitfile_device — Device unit configuration
name.device
A unit configuration file whose name ends in
.device encodes information about a device unit as
exposed in the sysfs/ udev(7) device tree.
This unit type has no specific options. See unitfile(5) for the common options of all unit configuration files.
The common configuration items are configured in the generic
[Unit] and [Install] sections. A
separate [Device] section does not exist, since no
device-specific options may be configured.
systemd will dynamically create device units for all kernel devices
that are marked with the "systemd" udev tag (by default all block and
network devices, and a few others). This may be used to define
dependencies between devices and other units. To tag a udev device, use
TAG+="systemd" in the udev rules file, see
udev(7) for details.
Device units are named after the /sys and
/dev paths they control. Example: the device
/dev/sda5 is exposed in systemd as
dev-sda5.device . For details about the escaping
logic used to convert a file system path to a unit name see unitfile(5) .
The settings of device units may either be configured via unit files, or directly from the udev database (which is recommended). The following udev device properties are understood by systemd:
SYSTEMD_WANTS=
Adds dependencies of type Wants from the
device unit to all listed units. This may be used to activate
arbitrary units when a specific device becomes available. Note that
this and the other tags are not taken into account unless the device
is tagged with the systemd string in the udev
database, because otherwise the device is not exposed as systemd
unit (see above). Note that systemd will only act on
Wants dependencies when a device first becomes
active, it will not act on them if they are added to devices that
are already active. Use SYSTEMD_READY= (see
below) to influence on which udev event to trigger the device
dependencies.
SYSTEMD_ALIAS=
Adds an additional alias name to the device unit. This must be an absolute path that is automatically transformed into a unit name. (See above.)
SYSTEMD_READY=
If set to 0, systemd will consider this device unplugged even
if it shows up in the udev tree. If this property is unset or set to
1, the device will be considered plugged the moment it shows up in
the udev tree. This property has no influence on the behavior when a
device disappears from the udev tree. This option is useful to
support devices that initially show up in an uninitialized state in
the tree, and for which a changed event is
generated the moment they are fully set up. Note that
SYSTEMD_WANTS= (see above) is not acted on as
long as SYSTEMD_READY=0 is set for a
device.
ID_MODEL_FROM_DATABASE=
,
ID_MODEL=
If set, this property is used as description string for the device unit.