<refnamediv>
<refname>udev</refname>
- <refpurpose>Linux dynamic device management</refpurpose>
+ <refpurpose>Dynamic device management</refpurpose>
</refnamediv>
<refsect1><title>Description</title>
sources is provided by the library libudev.</para>
</refsect1>
- <refsect1><title>Rules files</title>
+ <refsect1><title>Rules Files</title>
<para>The udev rules are read from the files located in the
system rules directory <filename>/usr/lib/udev/rules.d</filename>,
the volatile runtime directory <filename>/run/udev/rules.d</filename>
and the local administration directory <filename>/etc/udev/rules.d</filename>.
All rules files are collectively sorted and processed in lexical order,
regardless of the directories in which they live. However, files with
- identical file names replace each other. Files in <filename>/etc</filename>
+ identical filenames replace each other. Files in <filename>/etc</filename>
have the highest priority, files in <filename>/run</filename> take precedence
over files with the same name in <filename>/lib</filename>. This can be
used to override a system-supplied rules file with a local file if needed;
a symlink in <filename>/etc</filename> with the same name as a rules file in
<filename>/lib</filename>, pointing to <filename>/dev/null</filename>,
- disables the rules file entirely.</para>
-
- <para>Rule files must have the extension <filename>.rules</filename>; other
- extensions are ignored.</para>
+ disables the rules file entirely. Rule files must have the extension
+ <filename>.rules</filename>; other extensions are ignored.</para>
<para>Every line in the rules file contains at least one key-value pair.
- Except for empty lines or lines beginning with '#', which are ignored.
+ Except for empty lines or lines beginning with <literal>#</literal>, which are ignored.
There are two kinds of keys: match and assignment.
If all match keys match against their values, the rule gets applied and the
assignment keys get the specified values assigned.</para>
one and the same parent device.</para>
<variablelist class='udev-directives'>
<varlistentry>
- <term><option>ACTION</option></term>
+ <term><varname>ACTION</varname></term>
<listitem>
<para>Match the name of the event action.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>DEVPATH</option></term>
+ <term><varname>DEVPATH</varname></term>
<listitem>
<para>Match the devpath of the event device.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>KERNEL</option></term>
+ <term><varname>KERNEL</varname></term>
<listitem>
<para>Match the name of the event device.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>NAME</option></term>
+ <term><varname>NAME</varname></term>
<listitem>
<para>Match the name of a network interface. It can be used once the
NAME key has been set in one of the preceding rules.</para>
</varlistentry>
<varlistentry>
- <term><option>SYMLINK</option></term>
+ <term><varname>SYMLINK</varname></term>
<listitem>
<para>Match the name of a symlink targeting the node. It can
be used once a SYMLINK key has been set in one of the preceding
</varlistentry>
<varlistentry>
- <term><option>SUBSYSTEM</option></term>
+ <term><varname>SUBSYSTEM</varname></term>
<listitem>
<para>Match the subsystem of the event device.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>DRIVER</option></term>
+ <term><varname>DRIVER</varname></term>
<listitem>
<para>Match the driver name of the event device. Only set this key for devices
which are bound to a driver at the time the event is generated.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>ATTR{<replaceable>filename</replaceable>}</option></term>
+ <term><varname>ATTR{<replaceable>filename</replaceable>}</varname></term>
<listitem>
<para>Match sysfs attribute values of the event device. Trailing
whitespace in the attribute values is ignored unless the specified match
</varlistentry>
<varlistentry>
- <term><option>KERNELS</option></term>
+ <term><varname>KERNELS</varname></term>
<listitem>
<para>Search the devpath upwards for a matching device name.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>SUBSYSTEMS</option></term>
+ <term><varname>SUBSYSTEMS</varname></term>
<listitem>
<para>Search the devpath upwards for a matching device subsystem name.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>DRIVERS</option></term>
+ <term><varname>DRIVERS</varname></term>
<listitem>
<para>Search the devpath upwards for a matching device driver name.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>ATTRS{<replaceable>filename</replaceable>}</option></term>
+ <term><varname>ATTRS{<replaceable>filename</replaceable>}</varname></term>
<listitem>
<para>Search the devpath upwards for a device with matching sysfs attribute values.
- If multiple <option>ATTRS</option> matches are specified, all of them
+ If multiple <varname>ATTRS</varname> matches are specified, all of them
must match on the same device. Trailing whitespace in the attribute values is ignored
unless the specified match value itself contains trailing whitespace.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>TAGS</option></term>
+ <term><varname>TAGS</varname></term>
<listitem>
<para>Search the devpath upwards for a device with matching tag.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>ENV{<replaceable>key</replaceable>}</option></term>
+ <term><varname>ENV{<replaceable>key</replaceable>}</varname></term>
<listitem>
<para>Match against a device property value.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>TAG</option></term>
+ <term><varname>TAG</varname></term>
<listitem>
<para>Match against a device tag.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>TEST{<replaceable>octal mode mask</replaceable>}</option></term>
+ <term><varname>TEST{<replaceable>octal mode mask</replaceable>}</varname></term>
<listitem>
<para>Test the existence of a file. An octal mode mask can be specified
if needed.</para>
</varlistentry>
<varlistentry>
- <term><option>PROGRAM</option></term>
+ <term><varname>PROGRAM</varname></term>
<listitem>
<para>Execute a program to determine whether there
is a match; the key is true if the program returns
executed program in the environment. The program's stdout
is available in the RESULT key.</para>
<para>This can only be used for very short-running foreground tasks. For details
- see <option>RUN</option>.</para>
+ see <varname>RUN</varname>.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>RESULT</option></term>
+ <term><varname>RESULT</varname></term>
<listitem>
<para>Match the returned string of the last PROGRAM call. This key can
be used in the same or in any later rule after a PROGRAM call.</para>
</varlistentry>
</variablelist>
- <para>Most of the fields support shell-style pattern matching. The following
+ <para>Most of the fields support shell glob pattern matching. The following
pattern characters are supported:</para>
<variablelist>
<varlistentry>
<term><literal>[]</literal></term>
<listitem>
<para>Matches any single character specified within the brackets. For
- example, the pattern string 'tty[SR]' would match either 'ttyS' or 'ttyR'.
- Ranges are also supported via the '-' character.
+ example, the pattern string <literal>tty[SR]</literal>
+ would match either <literal>ttyS</literal> or <literal>ttyR</literal>.
+ Ranges are also supported via the <literal>-</literal> character.
For example, to match on the range of all digits, the pattern [0-9] could
- be used. If the first character following the '[' is a '!', any characters
- not enclosed are matched.</para>
+ be used. If the first character following the <literal>[</literal> is a
+ <literal>!</literal>, any characters not enclosed are matched.</para>
</listitem>
</varlistentry>
</variablelist>
<para>The following keys can get values assigned:</para>
<variablelist class='udev-directives'>
<varlistentry>
- <term><option>NAME</option></term>
+ <term><varname>NAME</varname></term>
<listitem>
<para>The name to use for a network interface. The name of a device node
cannot be changed by udev, only additional symlinks can be created.</para>
</varlistentry>
<varlistentry>
- <term><option>SYMLINK</option></term>
+ <term><varname>SYMLINK</varname></term>
<listitem>
<para>The name of a symlink targeting the node. Every matching rule adds
this value to the list of symlinks to be created.</para>
<para>The set of characters to name a symlink is limited. Allowed
- characters are [0-9A-Za-z#+-.:=@_/], valid UTF-8 character sequences,
- and "\x00" hex encoding. All other characters are replaced by
- a '_' character.</para>
+ characters are <literal>0-9A-Za-z#+-.:=@_/</literal>, valid UTF-8 character
+ sequences, and <literal>\x00</literal> hex encoding. All other
+ characters are replaced by a <literal>_</literal> character.</para>
<para>Multiple symlinks may be specified by separating the names by the
space character. In case multiple devices claim the same name, the link
always points to the device with the highest link_priority. If the current
</varlistentry>
<varlistentry>
- <term><option>OWNER</option>, <option>GROUP</option>, <option>MODE</option></term>
+ <term><varname>OWNER</varname>, <varname>GROUP</varname>, <varname>MODE</varname></term>
<listitem>
<para>The permissions for the device node. Every specified value overrides
the compiled-in default value.</para>
</varlistentry>
<varlistentry>
- <term><option>ATTR{<replaceable>key</replaceable>}</option></term>
+ <term><varname>SECLABEL{<replaceable>module</replaceable>}</varname></term>
+ <listitem>
+ <para>Applies the specified Linux Security Module label to the device node.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ATTR{<replaceable>key</replaceable>}</varname></term>
<listitem>
<para>The value that should be written to a sysfs attribute of the
event device.</para>
</varlistentry>
<varlistentry>
- <term><option>ENV{<replaceable>key</replaceable>}</option></term>
+ <term><varname>ENV{<replaceable>key</replaceable>}</varname></term>
<listitem>
- <para>Set a device property value. Property names with a leading '.'
+ <para>Set a device property value. Property names with a leading <literal>.</literal>
are neither stored in the database nor exported to events or
external tools (run by, say, the PROGRAM match key).</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>TAG</option></term>
+ <term><varname>TAG</varname></term>
<listitem>
<para>Attach a tag to a device. This is used to filter events for users
of libudev's monitor functionality, or to enumerate a group of tagged
</varlistentry>
<varlistentry>
- <term><option>RUN{<replaceable>type</replaceable>}</option></term>
+ <term><varname>RUN{<replaceable>type</replaceable>}</varname></term>
<listitem>
<para>Add a program to the list of programs to be executed after processing all the
rules for a specific event, depending on <literal>type</literal>:</para>
<varlistentry>
<term><literal>builtin</literal></term>
<listitem>
- <para>As <option>program</option>, but use one of the built-in programs rather
+ <para>As <varname>program</varname>, but use one of the built-in programs rather
than an external one.</para>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
- <term><option>LABEL</option></term>
+ <term><varname>LABEL</varname></term>
<listitem>
<para>A named label to which a GOTO may jump.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>GOTO</option></term>
+ <term><varname>GOTO</varname></term>
<listitem>
<para>Jumps to the next LABEL with a matching name.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>IMPORT{<replaceable>type</replaceable>}</option></term>
+ <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term>
<listitem>
<para>Import a set of variables as device properties,
depending on <literal>type</literal>:</para>
<para>Execute an external program specified as the assigned value and
import its output, which must be in environment key
format. Path specification, command/argument separation,
- and quoting work like in <option>RUN</option>.</para>
+ and quoting work like in <varname>RUN</varname>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>builtin</literal></term>
<listitem>
- <para>As <option>program</option>, but use one of the built-in programs rather
- than an external one.</para>
+ <para>Similar to <literal>program</literal>, but use one of the
+ built-in programs rather than an external one.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>cmdline</literal></term>
<listitem>
<para>Import a single property from the kernel command line. For simple flags
- the value of the property is set to '1'.</para>
+ the value of the property is set to <literal>1</literal>.</para>
</listitem>
</varlistentry>
<varlistentry>
<para>Import the stored keys from the parent device by reading
the database entry of the parent device. The value assigned to
<option>IMPORT{parent}</option> is used as a filter of key names
- to import (with the same shell-style pattern matching used for
+ to import (with the same shell glob pattern matching used for
comparisons).</para>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
- <term><option>WAIT_FOR</option></term>
+ <term><varname>WAIT_FOR</varname></term>
<listitem>
<para>Wait for a file to become available or until a timeout of
10 seconds expires. The path is relative to the sysfs device;
</varlistentry>
<varlistentry>
- <term><option>OPTIONS</option></term>
+ <term><varname>OPTIONS</varname></term>
<listitem>
<para>Rule and device options:</para>
<variablelist class='udev-directives'>
<term><option>static_node=</option></term>
<listitem>
<para>Apply the permissions specified in this rule to the static device node with
- the specified name. Static device node creation can be requested by kernel modules.
- These nodes might not have a corresponding kernel device at the time systemd-udevd is
- started; they can trigger automatic kernel module loading.</para>
+ the specified name. Also, for every tag specified in this rule, create a symlink
+ in the directory
+ <filename>/run/udev/static_node-tags/<replaceable>tag</replaceable></filename>
+ pointing at the static device node with the specified name. Static device node
+ creation is performed by systemd-tmpfiles before systemd-udevd is started. The
+ static nodes might not have a corresponding kernel device; they are used to
+ trigger automatic kernel module loading when they are accessed.</para>
</listitem>
</varlistentry>
<varlistentry>
</varlistentry>
</variablelist>
- <para>The <option>NAME</option>, <option>SYMLINK</option>, <option>PROGRAM</option>,
- <option>OWNER</option>, <option>GROUP</option>, <option>MODE</option> and <option>RUN</option>
- fields support simple string substitutions. The <option>RUN</option>
+ <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>, <varname>PROGRAM</varname>,
+ <varname>OWNER</varname>, <varname>GROUP</varname>, <varname>MODE</varname> and <varname>RUN</varname>
+ fields support simple string substitutions. The <varname>RUN</varname>
substitutions are performed after all rules have been processed, right before the program
is executed, allowing for the use of device properties set by earlier matching
rules. For all other fields, substitutions are performed while the individual rule is
<varlistentry>
<term><option>$number</option>, <option>%n</option></term>
<listitem>
- <para>The kernel number for this device. For example, 'sda3' has
- kernel number of '3'</para>
+ <para>The kernel number for this device. For example,
+ <literal>sda3</literal> has kernel number <literal>3</literal>.</para>
</listitem>
</varlistentry>
<listitem>
<para>The string returned by the external program requested with PROGRAM.
A single part of the string, separated by a space character, may be selected
- by specifying the part number as an attribute: <option>%c{N}</option>.
- If the number is followed by the '+' character, this part plus all remaining parts
- of the result string are substituted: <option>%c{N+}</option></para>
+ by specifying the part number as an attribute: <literal>%c{N}</literal>.
+ If the number is followed by the <literal>+</literal> character, this part plus all remaining parts
+ of the result string are substituted: <literal>%c{N+}</literal>.</para>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
- <term><literal>%%</literal></term>
+ <term><option>%%</option></term>
<listitem>
- <para>The '%' character itself.</para>
+ <para>The <literal>%</literal> character itself.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><literal>$$</literal></term>
+ <term><option>$$</option></term>
<listitem>
- <para>The '$' character itself.</para>
+ <para>The <literal>$</literal> character itself.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
+ <refsect1><title>Hardware Database Files</title>
+ <para>The hwdb files are read from the files located in the
+ system hwdb directory <filename>/usr/lib/udev/hwdb.d</filename>,
+ the volatile runtime directory <filename>/run/udev/hwdb.d</filename>
+ and the local administration directory <filename>/etc/udev/hwdb.d</filename>.
+ All hwdb files are collectively sorted and processed in lexical order,
+ regardless of the directories in which they live. However, files with
+ identical filenames replace each other. Files in <filename>/etc</filename>
+ have the highest priority, files in <filename>/run</filename> take precedence
+ over files with the same name in <filename>/lib</filename>. This can be
+ used to override a system-supplied hwdb file with a local file if needed;
+ a symlink in <filename>/etc</filename> with the same name as a hwdb file in
+ <filename>/lib</filename>, pointing to <filename>/dev/null</filename>,
+ disables the hwdb file entirely. hwdb files must have the extension
+ <filename>.hwdb</filename>; other extensions are ignored.</para>
+
+ <para>The hwdb file contains data records consisting of matches and
+ associated key-value pairs. Every record in the hwdb starts with one or
+ more match string, specifying a shell glob to compare the database
+ lookup string against. Multiple match lines are specified in additional
+ consecutive lines. Every match line is compared indivdually, they are
+ combined by OR. Every match line must start at the first character of
+ the line.</para>
+
+ <para>The match lines are followed by one or more key-value pair lines, which
+ are recognized by a leading space character. The key name and value are separated
+ by <literal>=</literal>. An empty line signifies the end
+ of a record. Lines beginning with <literal>#</literal> are ignored.</para>
+
+ <para>The content of all hwdb files is read by
+ <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ and compiled to a binary database located at <filename>/etc/udev/hwdb.bin</filename>.
+ During runtime only the binary database is used.</para>
+ </refsect1>
+
<refsect1>
<title>See Also</title>
<para><citerefentry>
~ianmdlvl / elogind.git / blobdiff