systemd-udevd.service

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



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



systemd 246                                             SYSTEMD-UDEVD.SERVICE(8)