systemd-udevd(8) - man - phpman

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

       /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 each RUN{program} parameter 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_level=, rd.udev.log_level=
           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 each RUN{program} parameter 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 249                                                                 SYSTEMD-UDEVD.SERVICE(8)