systemd-udevd(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | KERNEL COMMAND LINE | SEE ALSO | COLOPHON

SYSTEMD-UDEVD.SERVICE(8)    systemd-udevd.service   SYSTEMD-UDEVD.SERVICE(8)

NAME         top

       systemd-udevd.service, systemd-udevd-control.socket, systemd-udevd-
       kernel.socket, systemd-udevd - Device event managing daemon

SYNOPSIS         top

       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         top

       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         top

       -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.

KERNEL COMMAND LINE         top

       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.

SEE ALSO         top

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

COLOPHON         top

       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 2020-09-18.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-09-18.)  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: systemd.link(5)udev.conf(5)30-systemd-environment-d-generator(7)file-hierarchy(7)systemd.index(7)systemd-vconsole-setup(8)systemd-vconsole-setup.service(8)