X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=man%2Fsystemd.device.xml;h=619fe1968046bfab9b6930a291179c53ccaeed10;hb=b4f052a05ab66d78290892382f33f20593001064;hp=3f6d012c11bf72fe54db45343f348e1bdb121bbe;hpb=e670b166a08b7c1031a9e7d7675fa9a29c3e19c9;p=elogind.git
diff --git a/man/systemd.device.xml b/man/systemd.device.xml
index 3f6d012c1..619fe1968 100644
--- a/man/systemd.device.xml
+++ b/man/systemd.device.xml
@@ -55,7 +55,7 @@
Description
A unit configuration file whose name ends in
- .device encodes information about
+ .device encodes information about
a device unit as exposed in the
sysfs/udev7
device tree.
@@ -70,17 +70,20 @@
since no device-specific options may be
configured.
- systemd will automatically create dynamic 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.
+ 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
+ udev7
+ for details.
Device units are named after the
/sys and
/dev paths they control. Example:
- the device /dev/sda5 is exposed
+ 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
@@ -93,24 +96,41 @@
The settings of device units may either be
configured via unit files, or directly from the udev
- database (which is recommended). The following udev
+ database (which is recommended). The following udev device
properties are understood by systemd:
SYSTEMD_WANTS=
+ SYSTEMD_USER_WANTS=
Adds dependencies of
- type Wants from
- this unit to all listed units. This
- may be used to activate arbitrary
- units, when a specific device becomes
- available. Note that this and the
+ type Wants from the
+ device unit to all listed units. The
+ first form is used by the system
+ systemd instance, the second by user
+ systemd instances. Those settings 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
+ systemd string in
the udev database, because otherwise
- the device is not exposed as systemd
- unit.
+ the device is not exposed as a 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 dependencies.
+
@@ -124,21 +144,27 @@
SYSTEMD_READY=
- If set to 0 systemd
+ 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
+ to 1, the device will be considered
+ plugged if it is visible 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
+ 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.
+ 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.