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| author | Mao <littlecvr@gmail.com> | 2018-02-01 17:33:13 +0800 |
|---|---|---|
| committer | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2018-02-09 11:59:03 +0100 |
| commit | 792cc203a67edb201073351f5c766fce3d5eab45 (patch) | |
| tree | 4e3050518771ab7139574032b196bfea5f1b8843 /man/udevadm.xml | |
| parent | 302af1c250c2c64f608187ab1efb8e4f1f442951 (diff) | |
| download | systemd-792cc203a67edb201073351f5c766fce3d5eab45.tar.gz | |
udevadm: allow trigger command to be synchronous
There are cases that we want to trigger and settle only specific
commands. For example, let's say at boot time we want to make sure all
the graphics devices are working correctly because it's critical for
booting, but not the USB subsystem (we'll trigger USB events later). So
we do:
udevadm trigger --action="add" --subsystem-match="graphics"
udevadm settle
However, we cannot block the kernel from emitting kernel events from
discovering USB devices. So if any of the USB kernel event was emitted
before the settle command, the settle command would still wait for the
entire queue to complete. And if the USB event takes a long time to be
processed, the system slows down.
The new `settle` option allows the `trigger` command to wait for only
the triggered events, and effectively solves this problem.
Diffstat (limited to 'man/udevadm.xml')
| -rw-r--r-- | man/udevadm.xml | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/man/udevadm.xml b/man/udevadm.xml index 753ddf98da..1495f556f3 100644 --- a/man/udevadm.xml +++ b/man/udevadm.xml @@ -335,6 +335,17 @@ device.</para> </listitem> </varlistentry> + <varlistentry> + <term><option>-w</option></term> + <term><option>--settle</option></term> + <listitem> + <para>Apart from triggering events, also waits for those events to + finish. Note that this is different from calling <command>udevadm + settle</command>. <command>udevadm settle</command> waits for all + events to finish. This option only waits for events triggered by + the same command to finish.</para> + </listitem> + </varlistentry> <xi:include href="standard-options.xml" xpointer="version" /> <xi:include href="standard-options.xml" xpointer="help" /> |