| SYSTEMD-UDEVD.SERVICE(8) | systemd-udevd.service | SYSTEMD-UDEVD.SERVICE(8) |
.SH "NAME" systemd-udevd.service, systemd-udevd-kernel.socket,
systemd-udevd-varlink.socket, systemd-udevd - Device event managing
daemon
.SH "SYNOPSIS"
.PP systemd-udevd.service
.PP systemd-udevd-kernel.socket
.PP systemd-udevd-varlink.socket
.HP 744u
/usr/lib/systemd/systemd-udevd
[--daemon]
[--debug]
[--children-max=]
[--exec-delay=]
[--event-timeout=]
[--resolve-names=early|late|never]
[--version]
[--help]
.SH "DESCRIPTION"
.PP systemd-udevd listens to kernel uevents. For every event,
systemd-udevd executes matching instructions specified in udev rules. See
udev(7).
.PP 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.
.SH "OPTIONS"
.PP -d, --daemon
Detach and run in the background.
Added in version 186.
.RE
.PP -D, --debug
Print debug messages to standard error.
Added in version 186.
.RE
.PP -c, --children-max=
Limit the number of events executed in parallel.
Added in version 186.
.RE
.PP -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.
Added in version 186.
.RE
.PP -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.
Added in version 216.
.RE
.PP -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.
Added in version 246.
.RE
.PP -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.
Added in version 186.
.RE
.PP -h, --help
Print a short help text and exit.
.RE
.PP -V, --version
Print a short version string and exit.
.RE
.SH "KERNEL COMMAND LINE"
.PP 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.
.PP udev.log_level=, rd.udev.log_level=
Set the log level.
Added in version 247.
.RE
.PP udev.trace[=BOOL],
rd.udev.trace[=BOOL]
Enable/disable trace logging. When enabled, udev.log_level= will be
ignored, and debug level is assumed.
Added in version 258.
.RE
.PP udev.children_max=, rd.udev.children_max=
Limit the number of events executed in parallel.
Added in version 186.
.RE
.PP 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.
Added in version 186.
.RE
.PP 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.
Added in version 216.
.RE
.PP 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.
Added in version 246.
.RE
.PP 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.
Added in version 246.
.RE
.PP net.ifnames=
Network interfaces are renamed to give them predictable names when possible.
It is enabled by default; specifying 0 disables it.
Added in version 199.
.RE
.PP 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.
Added in version 240.
.RE
.PP
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:
net.ifname_policy=keep,kernel,path,slot,onboard,01:23:45:67:89:ab net.ifname_policy=keep,kernel,path,slot,onboard,mac
This is mostly equivalent to creating the following .link files:
# 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
and
# 92-name-policy-for-all.link [Match] OriginalName=* [Link] NamePolicy=keep kernel path slot onboard mac AlternativeNamePolicy=path slot onboard mac
Added in version 250.
.RE
.SH "SEE ALSO"
.PP udev.conf(5), udev(7), udevadm(8)
| systemd 262.2 |