systemd-udevd.service

Index · Directives systemd 234

## 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`

`/usr/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

`--daemon`

  Detach and run in the background.

`--debug`

  Print debug messages to standard error.

`--children-max=`

  Limit the number of events executed in parallel.

`--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.

`--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.

`--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.

`--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.

## See Also

udev.conf(5), udev(7), udevadm(8)