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514094f9 | 1 | <?xml version='1.0'?> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
db9ecf05 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
f48f7543 | 5 | |
dfdebb1b ZJS |
6 | <refentry id="systemd-udevd.service" |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
8 | ||
63749b1a | 9 | <refentryinfo> |
49408357 | 10 | <title>systemd-udevd.service</title> |
d3a2386d | 11 | <productname>systemd</productname> |
63749b1a | 12 | </refentryinfo> |
420a506e | 13 | |
63749b1a | 14 | <refmeta> |
bad1837c | 15 | <refentrytitle>systemd-udevd.service</refentrytitle> |
63749b1a | 16 | <manvolnum>8</manvolnum> |
63749b1a | 17 | </refmeta> |
420a506e | 18 | |
63749b1a | 19 | <refnamediv> |
51dfddc2 CG |
20 | <refname>systemd-udevd.service</refname> |
21 | <refname>systemd-udevd-control.socket</refname> | |
22 | <refname>systemd-udevd-kernel.socket</refname> | |
bad1837c | 23 | <refname>systemd-udevd</refname> |
b79f817b | 24 | <refpurpose>Device event managing daemon</refpurpose> |
63749b1a | 25 | </refnamediv> |
420a506e | 26 | |
63749b1a | 27 | <refsynopsisdiv> |
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28 | <para><filename>systemd-udevd.service</filename></para> |
29 | <para><filename>systemd-udevd-control.socket</filename></para> | |
30 | <para><filename>systemd-udevd-kernel.socket</filename></para> | |
b79f817b | 31 | |
63749b1a | 32 | <cmdsynopsis> |
12b42c76 | 33 | <command>/usr/lib/systemd/systemd-udevd</command> |
63749b1a | 34 | <arg><option>--daemon</option></arg> |
63749b1a | 35 | <arg><option>--debug</option></arg> |
9fa68615 KS |
36 | <arg><option>--children-max=</option></arg> |
37 | <arg><option>--exec-delay=</option></arg> | |
9719859c | 38 | <arg><option>--event-timeout=</option></arg> |
63749b1a | 39 | <arg><option>--resolve-names=early|late|never</option></arg> |
9fa68615 | 40 | <arg><option>--version</option></arg> |
63749b1a KS |
41 | <arg><option>--help</option></arg> |
42 | </cmdsynopsis> | |
b79f817b | 43 | |
63749b1a | 44 | </refsynopsisdiv> |
420a506e | 45 | |
63749b1a | 46 | <refsect1><title>Description</title> |
b8e8f0cb | 47 | <para><command>systemd-udevd</command> listens to kernel uevents. |
6fc5a404 ZJS |
48 | For every event, systemd-udevd executes matching instructions |
49 | specified in udev rules. See <citerefentry> | |
50 | <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum> | |
51 | </citerefentry>.</para> | |
52 | ||
203af57f ZJS |
53 | <para>The behavior of the daemon can be configured using |
54 | <citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
81c7dd89 LP |
55 | its command line options, environment variables, and on the kernel |
56 | command line, or changed dynamically with <command>udevadm | |
203af57f | 57 | control</command>. |
6fc5a404 | 58 | </para> |
63749b1a | 59 | </refsect1> |
420a506e | 60 | |
63749b1a KS |
61 | <refsect1><title>Options</title> |
62 | <variablelist> | |
63 | <varlistentry> | |
a135d271 | 64 | <term><option>-d</option></term> |
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65 | <term><option>--daemon</option></term> |
66 | <listitem> | |
67 | <para>Detach and run in the background.</para> | |
68 | </listitem> | |
69 | </varlistentry> | |
dfdebb1b | 70 | |
63749b1a | 71 | <varlistentry> |
a135d271 | 72 | <term><option>-D</option></term> |
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73 | <term><option>--debug</option></term> |
74 | <listitem> | |
6db27428 | 75 | <para>Print debug messages to standard error.</para> |
9fa68615 KS |
76 | </listitem> |
77 | </varlistentry> | |
dfdebb1b | 78 | |
9fa68615 | 79 | <varlistentry> |
a34a2933 | 80 | <term><option>-c</option></term> |
9fa68615 | 81 | <term><option>--children-max=</option></term> |
63749b1a | 82 | <listitem> |
b8e8f0cb | 83 | <para>Limit the number of events executed in parallel.</para> |
63749b1a KS |
84 | </listitem> |
85 | </varlistentry> | |
dfdebb1b | 86 | |
63749b1a | 87 | <varlistentry> |
a34a2933 | 88 | <term><option>-e</option></term> |
9fa68615 | 89 | <term><option>--exec-delay=</option></term> |
63749b1a | 90 | <listitem> |
6db27428 | 91 | <para>Delay the execution of <varname>RUN</varname> |
66f756d4 | 92 | instructions by the given number of seconds. This option |
6db27428 ZJS |
93 | might be useful when debugging system crashes during |
94 | coldplug caused by loading non-working kernel | |
95 | modules.</para> | |
63749b1a KS |
96 | </listitem> |
97 | </varlistentry> | |
dfdebb1b | 98 | |
9719859c | 99 | <varlistentry> |
a34a2933 | 100 | <term><option>-t</option></term> |
9719859c HR |
101 | <term><option>--event-timeout=</option></term> |
102 | <listitem> | |
dd5eddd2 | 103 | <para>Set the number of seconds to wait for events to finish. After |
b938cb90 | 104 | this time, the event will be terminated. The default is 180 seconds.</para> |
9719859c HR |
105 | </listitem> |
106 | </varlistentry> | |
107 | ||
e2099267 MS |
108 | <varlistentry> |
109 | <term><option>-s</option></term> | |
110 | <term><option>--timeout-signal=</option></term> | |
111 | <listitem> | |
112 | <para>Set the signal which <filename>systemd-udevd</filename> will send to | |
cb713f16 | 113 | forked off processes after reaching event timeout. The setting can be overridden |
e2099267 MS |
114 | at boot time with the kernel command line option |
115 | <varname>udev.timeout_signal=</varname>. Setting to <constant>SIGABRT</constant> | |
116 | may be helpful in order to debug worker timeouts. Defaults to | |
117 | <constant>SIGKILL</constant>. Note that setting the option on the command line | |
118 | overrides the setting from the configuration file. | |
119 | </para> | |
120 | </listitem> | |
121 | </varlistentry> | |
122 | ||
63749b1a | 123 | <varlistentry> |
a34a2933 | 124 | <term><option>-N</option></term> |
9fa68615 | 125 | <term><option>--resolve-names=</option></term> |
63749b1a | 126 | <listitem> |
f13b388f | 127 | <para>Specify when systemd-udevd should resolve names of users and groups. |
73e231ab | 128 | When set to <option>early</option> (the default), names will be |
63749b1a | 129 | resolved when the rules are parsed. When set to |
73e231ab JE |
130 | <option>late</option>, names will be resolved for every event. |
131 | When set to <option>never</option>, names will never be resolved | |
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132 | and all devices will be owned by root.</para> |
133 | </listitem> | |
134 | </varlistentry> | |
dfdebb1b | 135 | |
a135d271 | 136 | <xi:include href="standard-options.xml" xpointer="help" /> |
dfdebb1b | 137 | <xi:include href="standard-options.xml" xpointer="version" /> |
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138 | </variablelist> |
139 | </refsect1> | |
420a506e | 140 | |
8f7f1a2b | 141 | <refsect1><title>Kernel command line</title> |
ccc9a4f9 | 142 | <variablelist class='kernel-commandline-options'> |
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143 | <para>Parameters prefixed with "rd." will be read when <command>systemd-udevd</command> is used in an |
144 | initrd, those without will be processed both in the initrd and on the host.</para> | |
8f7f1a2b | 145 | <varlistentry> |
64a3494c FB |
146 | <term><varname>udev.log_level=</varname></term> |
147 | <term><varname>rd.udev.log_level=</varname></term> | |
8f7f1a2b | 148 | <listitem> |
f47ad593 | 149 | <para>Set the log level.</para> |
8f7f1a2b KS |
150 | </listitem> |
151 | </varlistentry> | |
152 | <varlistentry> | |
1d84ad94 LP |
153 | <term><varname>udev.children_max=</varname></term> |
154 | <term><varname>rd.udev.children_max=</varname></term> | |
8f7f1a2b | 155 | <listitem> |
b8e8f0cb | 156 | <para>Limit the number of events executed in parallel.</para> |
8f7f1a2b KS |
157 | </listitem> |
158 | </varlistentry> | |
159 | <varlistentry> | |
1d84ad94 LP |
160 | <term><varname>udev.exec_delay=</varname></term> |
161 | <term><varname>rd.udev.exec_delay=</varname></term> | |
8f7f1a2b | 162 | <listitem> |
ed7e5fe3 | 163 | <para>Delay the execution of <varname>RUN</varname> instructions by the given |
b8e8f0cb ZJS |
164 | number of seconds. This option might be useful when |
165 | debugging system crashes during coldplug caused by loading | |
166 | non-working kernel modules.</para> | |
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167 | </listitem> |
168 | </varlistentry> | |
9719859c | 169 | <varlistentry> |
1d84ad94 LP |
170 | <term><varname>udev.event_timeout=</varname></term> |
171 | <term><varname>rd.udev.event_timeout=</varname></term> | |
9719859c HR |
172 | <listitem> |
173 | <para>Wait for events to finish up to the given number | |
174 | of seconds. This option might be useful if events are | |
dd5eddd2 | 175 | terminated due to kernel drivers taking too long to initialize.</para> |
9719859c HR |
176 | </listitem> |
177 | </varlistentry> | |
e2099267 MS |
178 | <varlistentry> |
179 | <term><varname>udev.timeout_signal=</varname></term> | |
180 | <term><varname>rd.udev.timeout_signal=</varname></term> | |
181 | <listitem> | |
182 | <para>Specifies a signal that <filename>systemd-udevd</filename> will send to | |
183 | workers on timeout. Note that kernel command line option overrides both the | |
184 | setting in the configuration file and the one on the program command line.</para> | |
185 | </listitem> | |
186 | </varlistentry> | |
95ac5230 LP |
187 | <varlistentry> |
188 | <term><varname>udev.blockdev_read_only</varname></term> | |
189 | <term><varname>rd.udev.blockdev_read_only</varname></term> | |
190 | <listitem> | |
191 | <para>If specified, mark all physical block devices read-only as they appear. Synthetic block | |
192 | devices (such as loopback block devices or device mapper devices) are left as they are. This is | |
193 | useful to guarantee that the contents of physical block devices remains unmodified during runtime, | |
194 | for example to implement fully stateless systems, for testing or for recovery situations where | |
195 | corrupted file systems shall not be corrupted further through accidental modification.</para> | |
196 | ||
197 | <para>A block device may be marked writable again by issuing the <command>blockdev | |
198 | --setrw</command> command, see <citerefentry | |
199 | project='man-pages'><refentrytitle>blockdev</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
200 | for details.</para> | |
201 | </listitem> | |
202 | </varlistentry> | |
0cf2d0d0 | 203 | <varlistentry> |
5a33334b | 204 | <term><varname>net.ifnames=</varname></term> |
0cf2d0d0 | 205 | <listitem> |
5a33334b | 206 | <para>Network interfaces are renamed to give them predictable names |
bcddd5bf | 207 | when possible. It is enabled by default; specifying 0 disables it.</para> |
0cf2d0d0 TG |
208 | </listitem> |
209 | </varlistentry> | |
f7e81fd9 LP |
210 | <varlistentry> |
211 | <term><varname>net.naming-scheme=</varname></term> | |
212 | <listitem> | |
213 | <para>Network interfaces are renamed to give them predictable names when possible (unless | |
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214 | <varname>net.ifnames=0</varname> is specified, see above). With this kernel command line option it |
215 | is possible to pick a specific version of this algorithm and override the default chosen at | |
216 | compilation time. Expects one of the naming scheme identifiers listed in | |
217 | <citerefentry><refentrytitle>systemd.net-naming-scheme</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
218 | or <literal>latest</literal> to select the latest scheme known (to this particular version of | |
219 | <filename>systemd-udevd.service</filename>).</para> | |
06da5c63 ZJS |
220 | |
221 | <para>Note that selecting a specific scheme is not sufficient to fully stabilize interface naming: | |
222 | the naming is generally derived from driver attributes exposed by the kernel. As the kernel is | |
223 | updated, previously missing attributes <filename>systemd-udevd.service</filename> is checking might | |
224 | appear, which affects older name derivation algorithms, too.</para> | |
f7e81fd9 LP |
225 | </listitem> |
226 | </varlistentry> | |
63749b1a | 227 | </variablelist> |
0b1e5b6e ZJS |
228 | <!-- when adding entries here, consider also adding them in kernel-command-line.xml --> |
229 | </refsect1> | |
7b86ada7 | 230 | |
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231 | <refsect1> |
232 | <title>See Also</title> | |
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233 | <para> |
234 | <citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
235 | <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
236 | <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
237 | </para> | |
63749b1a KS |
238 | </refsect1> |
239 | </refentry> |