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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | KERNEL COMMAND LINE | SEE ALSO | COLOPHON |
SYSTEMD-UDEVD.SERVICE(8) systemd-udevd.service SYSTEMD-UDEVD.SERVICE(8)
systemd-udevd.service, systemd-udevd-control.socket, systemd-udevd-
kernel.socket, systemd-udevd - Device event managing daemon
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]
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.
-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.
-s, --timeout-signal=
Set the signal which systemd-udevd will send to forked off
processes after reaching event timeout. The setting can be
overridden at boot time with the kernel command line option
udev.timeout_signal=. Setting to SIGABRT may be helpful in order
to debug worker timeouts. Defaults to SIGKILL. Note that setting
the option on the command line overrides the setting from the
configuration file.
-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.
Parameters prefixed with "rd." will be read when systemd-udevd is
used in an initrd, those without will be processed both in the initrd
and on the host.
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.
udev.timeout_signal=, rd.udev.timeout_signal=
Specifies a signal that systemd-udevd will send to workers on
timeout. Note that kernel command line option overrides both the
setting in the configuration file and the one on the program
command line.
udev.blockdev_read_only, rd.udev.blockdev_read_only
If specified, mark all physical block devices read-only as they
appear. Synthetic block devices (such as loopback block devices
or device mapper devices) are left as they are. This is useful to
guarantee that the contents of physical block devices remains
unmodified during runtime, for example to implement fully
stateless systems, for testing or for recovery situations where
corrupted file systems shall not be corrupted further through
accidental modification.
A block device may be marked writable again by issuing the
blockdev --setrw command, see blockdev(8) for details.
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.
udev.conf(5), udev(7), udevadm(8)
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
systemd 246 SYSTEMD-UDEVD.SERVICE(8)
Pages that refer to this page: 30-systemd-environment-d-generator(7) , systemd.index(7)