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1 | <?xml version='1.0'?> | |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> | |
5 | ||
6 | <refentry id="systemd-udevd.service" | |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
8 | ||
9 | <refentryinfo> | |
10 | <title>systemd-udevd.service</title> | |
11 | <productname>systemd</productname> | |
12 | </refentryinfo> | |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>systemd-udevd.service</refentrytitle> | |
16 | <manvolnum>8</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>systemd-udevd.service</refname> | |
21 | <refname>systemd-udevd-control.socket</refname> | |
22 | <refname>systemd-udevd-kernel.socket</refname> | |
23 | <refname>systemd-udevd</refname> | |
24 | <refpurpose>Device event managing daemon</refpurpose> | |
25 | </refnamediv> | |
26 | ||
27 | <refsynopsisdiv> | |
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> | |
31 | ||
32 | <cmdsynopsis> | |
33 | <command>/usr/lib/systemd/systemd-udevd</command> | |
34 | <arg><option>--daemon</option></arg> | |
35 | <arg><option>--debug</option></arg> | |
36 | <arg><option>--children-max=</option></arg> | |
37 | <arg><option>--exec-delay=</option></arg> | |
38 | <arg><option>--event-timeout=</option></arg> | |
39 | <arg><option>--resolve-names=early|late|never</option></arg> | |
40 | <arg><option>--version</option></arg> | |
41 | <arg><option>--help</option></arg> | |
42 | </cmdsynopsis> | |
43 | ||
44 | </refsynopsisdiv> | |
45 | ||
46 | <refsect1><title>Description</title> | |
47 | <para><command>systemd-udevd</command> listens to kernel uevents. | |
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 | ||
53 | <para>The behavior of the daemon can be configured using | |
54 | <citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
55 | its command line options, environment variables, and on the kernel | |
56 | command line, or changed dynamically with <command>udevadm | |
57 | control</command>. | |
58 | </para> | |
59 | </refsect1> | |
60 | ||
61 | <refsect1><title>Options</title> | |
62 | <variablelist> | |
63 | <varlistentry> | |
64 | <term><option>-d</option></term> | |
65 | <term><option>--daemon</option></term> | |
66 | <listitem> | |
67 | <para>Detach and run in the background.</para> | |
68 | </listitem> | |
69 | </varlistentry> | |
70 | ||
71 | <varlistentry> | |
72 | <term><option>-D</option></term> | |
73 | <term><option>--debug</option></term> | |
74 | <listitem> | |
75 | <para>Print debug messages to standard error.</para> | |
76 | </listitem> | |
77 | </varlistentry> | |
78 | ||
79 | <varlistentry> | |
80 | <term><option>-c=</option></term> | |
81 | <term><option>--children-max=</option></term> | |
82 | <listitem> | |
83 | <para>Limit the number of events executed in parallel.</para> | |
84 | </listitem> | |
85 | </varlistentry> | |
86 | ||
87 | <varlistentry> | |
88 | <term><option>-e=</option></term> | |
89 | <term><option>--exec-delay=</option></term> | |
90 | <listitem> | |
91 | <para>Delay the execution of <varname>RUN</varname> | |
92 | instructions by the given number of seconds. This option | |
93 | might be useful when debugging system crashes during | |
94 | coldplug caused by loading non-working kernel | |
95 | modules.</para> | |
96 | </listitem> | |
97 | </varlistentry> | |
98 | ||
99 | <varlistentry> | |
100 | <term><option>-t=</option></term> | |
101 | <term><option>--event-timeout=</option></term> | |
102 | <listitem> | |
103 | <para>Set the number of seconds to wait for events to finish. After | |
104 | this time, the event will be terminated. The default is 180 seconds.</para> | |
105 | </listitem> | |
106 | </varlistentry> | |
107 | ||
108 | <varlistentry> | |
109 | <term><option>-N=</option></term> | |
110 | <term><option>--resolve-names=</option></term> | |
111 | <listitem> | |
112 | <para>Specify when systemd-udevd should resolve names of users and groups. | |
113 | When set to <option>early</option> (the default), names will be | |
114 | resolved when the rules are parsed. When set to | |
115 | <option>late</option>, names will be resolved for every event. | |
116 | When set to <option>never</option>, names will never be resolved | |
117 | and all devices will be owned by root.</para> | |
118 | </listitem> | |
119 | </varlistentry> | |
120 | ||
121 | <xi:include href="standard-options.xml" xpointer="help" /> | |
122 | <xi:include href="standard-options.xml" xpointer="version" /> | |
123 | </variablelist> | |
124 | </refsect1> | |
125 | ||
126 | <refsect1><title>Kernel command line</title> | |
127 | <variablelist class='kernel-commandline-options'> | |
128 | <para>Parameters starting with "rd." will be read when | |
129 | <command>systemd-udevd</command> is used in an initrd.</para> | |
130 | <varlistentry> | |
131 | <term><varname>udev.log_priority=</varname></term> | |
132 | <term><varname>rd.udev.log_priority=</varname></term> | |
133 | <listitem> | |
134 | <para>Set the log level.</para> | |
135 | </listitem> | |
136 | </varlistentry> | |
137 | <varlistentry> | |
138 | <term><varname>udev.children_max=</varname></term> | |
139 | <term><varname>rd.udev.children_max=</varname></term> | |
140 | <listitem> | |
141 | <para>Limit the number of events executed in parallel.</para> | |
142 | </listitem> | |
143 | </varlistentry> | |
144 | <varlistentry> | |
145 | <term><varname>udev.exec_delay=</varname></term> | |
146 | <term><varname>rd.udev.exec_delay=</varname></term> | |
147 | <listitem> | |
148 | <para>Delay the execution of <varname>RUN</varname> instructions by the given | |
149 | number of seconds. This option might be useful when | |
150 | debugging system crashes during coldplug caused by loading | |
151 | non-working kernel modules.</para> | |
152 | </listitem> | |
153 | </varlistentry> | |
154 | <varlistentry> | |
155 | <term><varname>udev.event_timeout=</varname></term> | |
156 | <term><varname>rd.udev.event_timeout=</varname></term> | |
157 | <listitem> | |
158 | <para>Wait for events to finish up to the given number | |
159 | of seconds. This option might be useful if events are | |
160 | terminated due to kernel drivers taking too long to initialize.</para> | |
161 | </listitem> | |
162 | </varlistentry> | |
163 | <varlistentry> | |
164 | <term><varname>net.ifnames=</varname></term> | |
165 | <listitem> | |
166 | <para>Network interfaces are renamed to give them predictable names | |
167 | when possible. It is enabled by default; specifying 0 disables it.</para> | |
168 | </listitem> | |
169 | </varlistentry> | |
170 | <varlistentry> | |
171 | <term><varname>net.naming-scheme=</varname></term> | |
172 | <listitem> | |
173 | <para>Network interfaces are renamed to give them predictable names when possible (unless | |
174 | <varname>net.ifnames=0</varname> is specified, see above). With this kernel command line option it | |
175 | is possible to pick a specific version of this algorithm and override the default chosen at | |
176 | compilation time. Expects one of the naming scheme identifiers listed in | |
177 | <citerefentry><refentrytitle>systemd.net-naming-scheme</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
178 | or <literal>latest</literal> to select the latest scheme known (to this particular version of | |
179 | <filename>systemd-udevd.service</filename>).</para> | |
180 | ||
181 | <para>Note that selecting a specific scheme is not sufficient to fully stabilize interface naming: | |
182 | the naming is generally derived from driver attributes exposed by the kernel. As the kernel is | |
183 | updated, previously missing attributes <filename>systemd-udevd.service</filename> is checking might | |
184 | appear, which affects older name derivation algorithms, too.</para> | |
185 | </listitem> | |
186 | </varlistentry> | |
187 | </variablelist> | |
188 | <!-- when adding entries here, consider also adding them in kernel-command-line.xml --> | |
189 | </refsect1> | |
190 | ||
191 | <refsect1> | |
192 | <title>See Also</title> | |
193 | <para> | |
194 | <citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
195 | <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
196 | <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
197 | </para> | |
198 | </refsect1> | |
199 | </refentry> |