NAME¶
systemd-udevd.service, systemd-udevd-control.socket,
systemd-udevd-kernel.socket, systemd-udevd - Device event managing daemon
SYNOPSIS¶
systemd-udevd.service
systemd-udevd-control.socket
systemd-udevd-kernel.socket
/lib/systemd/systemd-udevd [--daemon]
[--debug] [--children-max=] [--exec-delay=]
[--event-timeout=] [--resolve-names=early|late|never]
[--version] [--help]
DESCRIPTION¶
systemd-udevd listens to kernel uevents. For every event, systemd-udevd
executes matching instructions specified in udev rules. See udev(7).
The behavior of the daemon can be configured using
udev.conf(5), its command line options, environment variables, and on
the kernel command line, or changed dynamically with udevadm
control.
OPTIONS¶
-d, --daemon
Detach and run in the background.
-D, --debug
Print debug messages to standard error.
-c=, --children-max=
Limit the number of events executed in parallel.
-e=, --exec-delay=
Delay the execution of RUN instructions by the
given number of seconds. This option might be useful when debugging system
crashes during coldplug caused by loading non-working kernel modules.
-t=, --event-timeout=
Set the number of seconds to wait for events to finish.
After this time, the event will be terminated. The default is 180
seconds.
-N=, --resolve-names=
Specify when systemd-udevd should resolve names of users
and groups. When set to early (the default), names will be resolved
when the rules are parsed. When set to late, names will be resolved for
every event. When set to never, names will never be resolved and all
devices will be owned by root.
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
KERNEL COMMAND LINE¶
Parameters starting with "rd." will be read when systemd-udevd
is used in an initrd.
udev.log_priority=, rd.udev.log_priority=
Set the log level.
udev.children_max=, rd.udev.children_max=
Limit the number of events executed in parallel.
udev.exec_delay=, rd.udev.exec_delay=
Delay the execution of RUN instructions by the
given number of seconds. This option might be useful when debugging system
crashes during coldplug caused by loading non-working kernel modules.
udev.event_timeout=, rd.udev.event_timeout=
Wait for events to finish up to the given number of
seconds. This option might be useful if events are terminated due to kernel
drivers taking too long to initialize.
net.ifnames=
Network interfaces are renamed to give them predictable
names when possible. It is enabled by default; specifying 0 disables it.
net.naming-scheme=
Network interfaces are renamed to give them predictable
names when possible (unless
net.ifnames=0 is specified, see above). The
names are derived from various device metadata fields. Newer versions of
systemd-udevd.service take more of these fields into account, improving (and
thus possibly changing) the names used for the same devices. With this kernel
command line option it is possible to pick a specific version of this
algorithm. It expects a naming scheme identifier as argument. Currently the
following identifiers are known: "v238", "v239",
"v240" which each implement the naming scheme that was the default
in the indicated systemd version. In addition, "latest" may be used
to designate the latest scheme known (to this particular version of
systemd-udevd.service).
Note that selecting a specific scheme is not sufficient to fully
stabilize interface naming: the naming is generally derived from driver
attributes exposed by the kernel. As the kernel is updated, previously
missing attributes systemd-udevd.service is checking might appear, which
affects older name derivation algorithms, too.
