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
- -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). With this kernel command line option it is possible to pick a specific version of this algorithm and override the default chosen at compilation time. Expects one of the naming scheme identifiers listed in systemd.net-naming-scheme(7), or "latest" to select 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.
See Also
Referenced By
file-hierarchy(7), kernel-command-line(7), systemd.directives(7), systemd.exec(5), systemd.index(7), systemd.link(5), systemd.net-naming-scheme(7), systemd-vconsole-setup.service(8), udev(7), udevadm(8), udev.conf(5).
The man pages systemd-udevd(8), systemd-udevd-control.socket(8) and systemd-udevd-kernel.socket(8) are aliases of systemd-udevd.service(8).