NAME
systemd-udevd.service, systemd-udevd-control.socket, systemd-udevd-kernel.socket, systemd-udevd - Device event managing daemonSYNOPSIS
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, --daemonDetach 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.
net.ifname-policy=policy1[,policy2,...][,MAC]
Specifies naming policies applied when
renaming network interfaces. Takes a list of policies and an optional MAC
address separated with comma. Each policy value must be one of the policies
understood by the NamePolicy= setting in .link files, e.g.
"onboard" or "path". See systemd.link(5) for more
details. When the MAC address is specified, the policies are applied to the
interface which has the address. When no MAC address is specified, the
policies are applied to all interfaces. This kernel command line argument can
be specified multiple times.
This argument is not directly read by systemd-udevd, but is instead
converted to a .link file by systemd-network-generator.service(8). For
this argument to take effect, systemd-network-generator.service must be
enabled.
Example:
This is mostly equivalent to creating the following .link files:
and
net.ifname-policy=keep,kernel,path,slot,onboard,01:23:45:67:89:ab net.ifname-policy=keep,kernel,path,slot,onboard,mac
# 91-name-policy-with-mac.link [Match] MACAddress=01:23:45:67:89:ab [Link] NamePolicy=keep kernel path slot onboard AlternativeNamePolicy=path slot onboard
# 92-name-policy-for-all.link [Match] OriginalName=* [Link] NamePolicy=keep kernel path slot onboard mac AlternativeNamePolicy=path slot onboard mac
SEE ALSO
udev.conf(5), udev(7), udevadm(8)systemd 252 |