<refpurpose>Dynamic device management</refpurpose>
</refnamediv>
- <refsect1><title>Description</title>
+ <refsect1>
+ <title>Description</title>
<para>udev supplies the system software with device events, manages permissions
of device nodes and may create additional symlinks in the <filename>/dev/</filename>
directory, or renames network interfaces. The kernel usually just assigns unpredictable
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 directories
<filename>/usr/lib/udev/rules.d</filename> and <filename>/usr/local/lib/udev/rules.d</filename>, the
volatile runtime directory <filename>/run/udev/rules.d</filename> and the local administration
pointing to the device node, or run a specified program as part of
the event handling.</para>
- <para>A rule consists of a comma-separated list of one or more key-value pairs.
- Each key has a distinct operation, depending on the used operator. Valid
- operators are:</para>
- <variablelist>
- <varlistentry>
- <term><literal>==</literal></term>
- <listitem>
- <para>Compare for equality.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><literal>!=</literal></term>
- <listitem>
- <para>Compare for inequality.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><literal>=</literal></term>
- <listitem>
- <para>Assign a value to a key. Keys that represent a list are reset
- and only this single value is assigned.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><literal>+=</literal></term>
- <listitem>
- <para>Add the value to a key that holds a list of entries.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><literal>-=</literal></term>
- <listitem>
- <para>Remove the value from a key that holds a list of entries.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><literal>:=</literal></term>
- <listitem>
- <para>Assign a value to a key finally; disallow any later changes.</para>
- </listitem>
- </varlistentry>
- </variablelist>
-
- <para>The following key names can be used to match against device properties.
- Some of the keys also match against properties of the parent devices in sysfs,
- not only the device that has generated the event. If multiple keys that match
- a parent device are specified in a single rule, all these keys must match at
- one and the same parent device.</para>
- <variablelist class='udev-directives'>
- <varlistentry>
- <term><varname>ACTION</varname></term>
- <listitem>
- <para>Match the name of the event action.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>DEVPATH</varname></term>
- <listitem>
- <para>Match the devpath of the event device.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>KERNEL</varname></term>
- <listitem>
- <para>Match the name of the event device.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <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>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <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
- rules. There may be multiple symlinks; only one needs to match.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>SUBSYSTEM</varname></term>
- <listitem>
- <para>Match the subsystem of the event device.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <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><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
- value itself contains trailing whitespace.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term>
- <listitem>
- <para>Match a kernel parameter value.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>KERNELS</varname></term>
- <listitem>
- <para>Search the devpath upwards for a matching device name.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>SUBSYSTEMS</varname></term>
- <listitem>
- <para>Search the devpath upwards for a matching device subsystem name.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>DRIVERS</varname></term>
- <listitem>
- <para>Search the devpath upwards for a matching device driver name.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ATTRS{<replaceable>filename</replaceable>}</varname></term>
- <listitem>
- <para>Search the devpath upwards for a device with matching sysfs attribute values.
- 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><varname>TAGS</varname></term>
- <listitem>
- <para>Search the devpath upwards for a device with matching tag.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ENV{<replaceable>key</replaceable>}</varname></term>
- <listitem>
- <para>Match against a device property value.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>CONST{<replaceable>key</replaceable>}</varname></term>
- <listitem>
- <para>Match against a system-wide constant. Supported keys are:</para>
- <variablelist>
- <varlistentry>
- <term><literal>arch</literal></term>
- <listitem>
- <para>System's architecture. See <option>ConditionArchitecture=</option> in
- <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for possible values.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>virt</literal></term>
- <listitem>
- <para>System's virtualization environment. See
- <citerefentry><refentrytitle>systemd-detect-virt</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- for possible values.</para>
- </listitem>
- </varlistentry>
- </variablelist>
- <para>Unknown keys will never match.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>TAG</varname></term>
- <listitem>
- <para>Match against a device tag.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <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>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <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 successfully. The device properties are made available to the executed program in the
- environment. The program's standard output is available in the <varname>RESULT</varname>
- key.</para>
-
- <para>This can only be used for very short-running foreground tasks. For details, see
- <varname>RUN</varname>.</para>
-
- <para>Note that multiple <varname>PROGRAM</varname> keys may be specified in one rule, and
- <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as
- <literal>==</literal>.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>RESULT</varname></term>
- <listitem>
- <para>Match the returned string of the last <varname>PROGRAM</varname> call.
- This key can be used in the same or in any later rule after a
- <varname>PROGRAM</varname> call.</para>
- </listitem>
- </varlistentry>
- </variablelist>
-
- <para>Most of the fields support shell glob pattern matching and
- alternate patterns. The following special characters are supported:</para>
- <variablelist>
- <varlistentry>
- <term><literal>*</literal></term>
- <listitem>
- <para>Matches zero or more characters.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>?</literal></term>
- <listitem>
- <para>Matches any single character.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>[]</literal></term>
- <listitem>
- <para>Matches any single character specified within the brackets. For
- 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
- <literal>[0-9]</literal> could be used. If the first character
- following the <literal>[</literal> is a <literal>!</literal>,
- any characters not enclosed are matched.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>|</literal></term>
- <listitem>
- <para>Separates alternative patterns. For example, the pattern string
- <literal>abc|x*</literal> would match either <literal>abc</literal>
- or <literal>x*</literal>.</para>
- </listitem>
- </varlistentry>
- </variablelist>
-
- <para>The following keys can get values assigned:</para>
- <variablelist class='udev-directives'>
- <varlistentry>
- <term><varname>NAME</varname></term>
- <listitem>
- <para>The name to use for a network interface. See
- <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for a higher-level mechanism for setting the interface name.
- The name of a device node cannot be changed by udev, only additional
- symlinks can be created.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <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 <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
- device goes away, the links are re-evaluated and the device with the
- next highest link_priority becomes the owner of the link. If no
- link_priority is specified, the order of the devices (and which one of
- them owns the link) is undefined.</para>
- <para>Symlink names must never conflict with the kernel's default device
- node names, as that would result in unpredictable behavior.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <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>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <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>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term>
- <listitem>
- <para>The value that should be written to kernel parameter.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ENV{<replaceable>key</replaceable>}</varname></term>
- <listitem>
- <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, for example, the <varname>PROGRAM</varname>
- match key).</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <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
- devices. The implementation can only work efficiently if only a few
- tags are attached to a device. It is only meant to be used in
- contexts with specific device filter requirements, and not as a
- general-purpose flag. Excessive use might result in inefficient event
- handling.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>RUN{<replaceable>type</replaceable>}</varname></term>
- <listitem>
- <para>Specify a program to be executed after processing of all the rules for the event. With
- <literal>+=</literal>, this invocation is added to the list, and with <literal>=</literal> or
- <literal>:=</literal>, it replaces any previous contents of the list. Please note that both
- <literal>program</literal> and <literal>builtin</literal> types described below use a single
- list, so clearing the list with <literal>:=</literal> and <literal>=</literal> affects both
- types.</para>
-
- <para><replaceable>type</replaceable> may be:</para>
- <variablelist>
- <varlistentry>
- <term><literal>program</literal></term>
- <listitem>
- <para>Execute an external program specified as the assigned
- value. If no absolute path is given, the program is expected
- to live in <filename>/usr/lib/udev</filename>; otherwise, the
- absolute path must be specified.</para>
- <para>This is the default if no <replaceable>type</replaceable>
- is specified.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>builtin</literal></term>
- <listitem>
- <para>As <varname>program</varname>, but use one of the
- built-in programs rather than an external one.</para>
- </listitem>
- </varlistentry>
- </variablelist>
-
- <para>The program name and following arguments are separated by spaces. Single quotes can be
- used to specify arguments with spaces.</para>
-
- <para>This can only be used for very short-running foreground tasks. Running an event process for
- a long period of time may block all further events for this or a dependent device.</para>
-
- <para>Note that running programs that access the network or mount/unmount filesystems is not
- allowed inside of udev rules, due to the default sandbox that is enforced on
- <filename>systemd-udevd.service</filename>.</para>
-
- <para>Starting daemons or other long-running processes is not allowed; the forked processes,
- detached or not, will be unconditionally killed after the event handling has finished. In order
- to activate long-running processes from udev rules, provide a service unit and pull it in from a
- udev device using the <varname>SYSTEMD_WANTS</varname> device property. See
- <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for details.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>LABEL</varname></term>
- <listitem>
- <para>A named label to which a <varname>GOTO</varname> may jump.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>GOTO</varname></term>
- <listitem>
- <para>Jumps to the next <varname>LABEL</varname> with a matching name.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term>
- <listitem>
- <para>Import a set of variables as device properties, depending on
- <replaceable>type</replaceable>:</para>
-
- <variablelist>
- <varlistentry>
- <term><literal>program</literal></term>
- <listitem>
- <para>Execute an external program specified as the assigned
- value and, if it returns successfully,
- import its output, which must be in environment key
- format. Path specification, command/argument separation,
- and quoting work like in <varname>RUN</varname>.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>builtin</literal></term>
- <listitem>
- <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>file</literal></term>
- <listitem>
- <para>Import a text file specified as the assigned value, the content
- of which must be in environment key format.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>db</literal></term>
- <listitem>
- <para>Import a single property specified as the assigned value from the
- current device database. This works only if the database is already populated
- by an earlier event.</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 <literal>1</literal>.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><literal>parent</literal></term>
- <listitem>
- <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 glob pattern matching used for
- comparisons).</para>
- </listitem>
- </varlistentry>
- </variablelist>
-
- <para>This can only be used for very short-running foreground tasks. For details see
- <option>RUN</option>.</para>
-
- <para>Note that multiple <varname>IMPORT{}</varname> keys may be specified in one rule, and
- <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as
- <literal>==</literal>. The key is true if the import is successful, unless <literal>!=</literal>
- is used as the operator which causes the key to be true if the import failed.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>OPTIONS</varname></term>
- <listitem>
- <para>Rule and device options:</para>
- <variablelist class='udev-directives'>
- <varlistentry>
- <term><option>link_priority=<replaceable>value</replaceable></option></term>
- <listitem>
- <para>Specify the priority of the created symlinks. Devices with higher
- priorities overwrite existing symlinks of other devices. The default is 0.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><option>string_escape=<replaceable>none|replace</replaceable></option></term>
- <listitem>
- <para>Usually, control and other possibly unsafe characters are replaced
- in strings used for device naming. The mode of replacement can be specified
- with this option.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><option>static_node=</option></term>
- <listitem>
- <para>Apply the permissions specified in this rule to the
- static device node with 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>
- <term><option>watch</option></term>
- <listitem>
- <para>Watch the device node with inotify; when the node is
- closed after being opened for writing, a change uevent is
- synthesized.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><option>nowatch</option></term>
- <listitem>
- <para>Disable the watching of a device node with inotify.</para>
- </listitem>
- </varlistentry>
+ <para>A rule consists of a comma-separated list of one or more key-operator-value expressions.
+ Each expression has a distinct effect, depending on the key and operator used.</para>
+
+ <refsect2>
+ <title>Operators</title>
+ <variablelist>
+ <varlistentry>
+ <term><literal>==</literal></term>
+ <listitem>
+ <para>Compare for equality.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><literal>!=</literal></term>
+ <listitem>
+ <para>Compare for inequality.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><literal>=</literal></term>
+ <listitem>
+ <para>Assign a value to a key. Keys that represent a list are reset
+ and only this single value is assigned.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><literal>+=</literal></term>
+ <listitem>
+ <para>Add the value to a key that holds a list of entries.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><literal>-=</literal></term>
+ <listitem>
+ <para>Remove the value from a key that holds a list of entries.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><literal>:=</literal></term>
+ <listitem>
+ <para>Assign a value to a key finally; disallow any later changes.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect2>
+
+ <refsect2>
+ <title>Values</title>
+ <para>Values are written as double quoted strings, such as ("string").
+ To include a quotation mark (") in the value, precede it by a backslash (\").
+ Any other occurrences of a character followed by a backslash are not further unescaped.
+ That is, "\t\n" is treated as four characters:
+ backslash, lowercase t, backslash, lowercase n.</para>
+
+ <para>The string can be prefixed with a lowercase e (e"string\n") to mark the string as
+ <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style escaped</ulink>.
+ For example, e"string\n" is parsed as 7 characters: 6 lowercase letters and a newline.
+ This can be useful for writting special characters when a kernel driver requires them.</para>
+
+ <para>Please note that <constant>NUL</constant> is not allowed in either string variant.</para>
+ </refsect2>
+
+ <refsect2>
+ <title>Keys</title>
+ <para>The following key names can be used to match against device properties.
+ Some of the keys also match against properties of the parent devices in sysfs,
+ not only the device that has generated the event. If multiple keys that match
+ a parent device are specified in a single rule, all these keys must match at
+ one and the same parent device.</para>
+ <variablelist class='udev-directives'>
+ <varlistentry>
+ <term><varname>ACTION</varname></term>
+ <listitem>
+ <para>Match the name of the event action.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>DEVPATH</varname></term>
+ <listitem>
+ <para>Match the devpath of the event device.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>KERNEL</varname></term>
+ <listitem>
+ <para>Match the name of the event device.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <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>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <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
+ rules. There may be multiple symlinks; only one needs to match.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SUBSYSTEM</varname></term>
+ <listitem>
+ <para>Match the subsystem of the event device.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <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><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
+ value itself contains trailing whitespace.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term>
+ <listitem>
+ <para>Match a kernel parameter value.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>KERNELS</varname></term>
+ <listitem>
+ <para>Search the devpath upwards for a matching device name.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SUBSYSTEMS</varname></term>
+ <listitem>
+ <para>Search the devpath upwards for a matching device subsystem name.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>DRIVERS</varname></term>
+ <listitem>
+ <para>Search the devpath upwards for a matching device driver name.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ATTRS{<replaceable>filename</replaceable>}</varname></term>
+ <listitem>
+ <para>Search the devpath upwards for a device with matching sysfs attribute values.
+ 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><varname>TAGS</varname></term>
+ <listitem>
+ <para>Search the devpath upwards for a device with matching tag.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ENV{<replaceable>key</replaceable>}</varname></term>
+ <listitem>
+ <para>Match against a device property value.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>CONST{<replaceable>key</replaceable>}</varname></term>
+ <listitem>
+ <para>Match against a system-wide constant. Supported keys are:</para>
+ <variablelist>
+ <varlistentry>
+ <term><literal>arch</literal></term>
+ <listitem>
+ <para>System's architecture. See <option>ConditionArchitecture=</option> in
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for possible values.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>virt</literal></term>
+ <listitem>
+ <para>System's virtualization environment. See
+ <citerefentry><refentrytitle>systemd-detect-virt</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ for possible values.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <para>Unknown keys will never match.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>TAG</varname></term>
+ <listitem>
+ <para>Match against a device tag.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <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>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <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 successfully. The device properties are made available to the executed program in the
+ environment. The program's standard output is available in the <varname>RESULT</varname>
+ key.</para>
+
+ <para>This can only be used for very short-running foreground tasks. For details, see
+ <varname>RUN</varname>.</para>
+
+ <para>Note that multiple <varname>PROGRAM</varname> keys may be specified in one rule, and
+ <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as
+ <literal>==</literal>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>RESULT</varname></term>
+ <listitem>
+ <para>Match the returned string of the last <varname>PROGRAM</varname> call.
+ This key can be used in the same or in any later rule after a
+ <varname>PROGRAM</varname> call.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Most of the fields support shell glob pattern matching and
+ alternate patterns. The following special characters are supported:</para>
+ <variablelist>
+ <varlistentry>
+ <term><literal>*</literal></term>
+ <listitem>
+ <para>Matches zero or more characters.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>?</literal></term>
+ <listitem>
+ <para>Matches any single character.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>[]</literal></term>
+ <listitem>
+ <para>Matches any single character specified within the brackets. For
+ 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
+ <literal>[0-9]</literal> could be used. If the first character
+ following the <literal>[</literal> is a <literal>!</literal>,
+ any characters not enclosed are matched.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>|</literal></term>
+ <listitem>
+ <para>Separates alternative patterns. For example, the pattern string
+ <literal>abc|x*</literal> would match either <literal>abc</literal>
+ or <literal>x*</literal>.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>The following keys can get values assigned:</para>
+ <variablelist class='udev-directives'>
+ <varlistentry>
+ <term><varname>NAME</varname></term>
+ <listitem>
+ <para>The name to use for a network interface. See
+ <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for a higher-level mechanism for setting the interface name.
+ The name of a device node cannot be changed by udev, only additional
+ symlinks can be created.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <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 <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
+ device goes away, the links are re-evaluated and the device with the
+ next highest link_priority becomes the owner of the link. If no
+ link_priority is specified, the order of the devices (and which one of
+ them owns the link) is undefined.</para>
+ <para>Symlink names must never conflict with the kernel's default device
+ node names, as that would result in unpredictable behavior.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <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>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <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>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term>
+ <listitem>
+ <para>The value that should be written to kernel parameter.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ENV{<replaceable>key</replaceable>}</varname></term>
+ <listitem>
+ <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, for example, the <varname>PROGRAM</varname>
+ match key).</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <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
+ devices. The implementation can only work efficiently if only a few
+ tags are attached to a device. It is only meant to be used in
+ contexts with specific device filter requirements, and not as a
+ general-purpose flag. Excessive use might result in inefficient event
+ handling.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>RUN{<replaceable>type</replaceable>}</varname></term>
+ <listitem>
+ <para>Specify a program to be executed after processing of all the rules for the event. With
+ <literal>+=</literal>, this invocation is added to the list, and with <literal>=</literal> or
+ <literal>:=</literal>, it replaces any previous contents of the list. Please note that both
+ <literal>program</literal> and <literal>builtin</literal> types described below use a single
+ list, so clearing the list with <literal>:=</literal> and <literal>=</literal> affects both
+ types.</para>
+
+ <para><replaceable>type</replaceable> may be:</para>
+ <variablelist>
+ <varlistentry>
+ <term><literal>program</literal></term>
+ <listitem>
+ <para>Execute an external program specified as the assigned
+ value. If no absolute path is given, the program is expected
+ to live in <filename>/usr/lib/udev</filename>; otherwise, the
+ absolute path must be specified.</para>
+ <para>This is the default if no <replaceable>type</replaceable>
+ is specified.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>builtin</literal></term>
+ <listitem>
+ <para>As <varname>program</varname>, but use one of the
+ built-in programs rather than an external one.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>The program name and following arguments are separated by spaces. Single quotes can be
+ used to specify arguments with spaces.</para>
+
+ <para>This can only be used for very short-running foreground tasks. Running an event process for
+ a long period of time may block all further events for this or a dependent device.</para>
+
+ <para>Note that running programs that access the network or mount/unmount filesystems is not
+ allowed inside of udev rules, due to the default sandbox that is enforced on
+ <filename>systemd-udevd.service</filename>.</para>
+
+ <para>Starting daemons or other long-running processes is not allowed; the forked processes,
+ detached or not, will be unconditionally killed after the event handling has finished. In order
+ to activate long-running processes from udev rules, provide a service unit and pull it in from a
+ udev device using the <varname>SYSTEMD_WANTS</varname> device property. See
+ <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>LABEL</varname></term>
+ <listitem>
+ <para>A named label to which a <varname>GOTO</varname> may jump.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>GOTO</varname></term>
+ <listitem>
+ <para>Jumps to the next <varname>LABEL</varname> with a matching name.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term>
+ <listitem>
+ <para>Import a set of variables as device properties, depending on
+ <replaceable>type</replaceable>:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><literal>program</literal></term>
+ <listitem>
+ <para>Execute an external program specified as the assigned
+ value and, if it returns successfully,
+ import its output, which must be in environment key
+ format. Path specification, command/argument separation,
+ and quoting work like in <varname>RUN</varname>.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>builtin</literal></term>
+ <listitem>
+ <para>Similar to <literal>program</literal>, but use one of the
+ built-in programs rather than an external one.</para>
+ </listitem>
+ </varlistentry>
<varlistentry>
- <term><option>db_persist</option></term>
- <listitem>
- <para>Set the flag (sticky bit) on the udev database entry
- of the event device. Device properties are then kept in the
- database even when
- <command>udevadm info --cleanup-db</command> is called.
- This option can be useful in certain cases
- (e.g. Device Mapper devices) for persisting device state
- on the transition from initramfs.</para>
- </listitem>
- </varlistentry>
- </variablelist>
- </listitem>
- </varlistentry>
- </variablelist>
-
- <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>,
- <varname>PROGRAM</varname>, <varname>OWNER</varname>,
- <varname>GROUP</varname>, <varname>MODE</varname>, <varname>SECLABEL</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 being
- processed. The available substitutions are:</para>
- <variablelist class='udev-directives'>
- <varlistentry>
- <term><option>$kernel</option>, <option>%k</option></term>
- <listitem>
- <para>The kernel name for this device.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$number</option>, <option>%n</option></term>
- <listitem>
- <para>The kernel number for this device. For example, <literal>sda3</literal> has kernel number
- 3.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$devpath</option>, <option>%p</option></term>
- <listitem>
- <para>The devpath of the device.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$id</option>, <option>%b</option></term>
- <listitem>
- <para>The name of the device matched while searching the devpath
- upwards for <option>SUBSYSTEMS</option>, <option>KERNELS</option>,
- <option>DRIVERS</option>, and <option>ATTRS</option>.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$driver</option></term>
- <listitem>
- <para>The driver name of the device matched while searching the
- devpath upwards for <option>SUBSYSTEMS</option>,
- <option>KERNELS</option>, <option>DRIVERS</option>, and
- <option>ATTRS</option>.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term>
- <listitem>
- <para>The value of a sysfs attribute found at the device where
- all keys of the rule have matched. If the matching device does not
- have such an attribute, and a previous <option>KERNELS</option>,
- <option>SUBSYSTEMS</option>, <option>DRIVERS</option>, or
- <option>ATTRS</option> test selected a parent device, then the
- attribute from that parent device is used.
- </para>
- <para>If the attribute is a symlink, the last element of the
- symlink target is returned as the value.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term>
- <listitem>
- <para>A device property value.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$major</option>, <option>%M</option></term>
- <listitem>
- <para>The kernel major number for the device.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$minor</option>, <option>%m</option></term>
- <listitem>
- <para>The kernel minor number for the device.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$result</option>, <option>%c</option></term>
- <listitem>
- <para>The string returned by the external program requested with
- <varname>PROGRAM</varname>.
- A single part of the string, separated by a space character, may be selected
- 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>
- <term><option>$parent</option>, <option>%P</option></term>
- <listitem>
- <para>The node name of the parent device.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$name</option></term>
- <listitem>
- <para>The current name of the device. If not changed by a rule, it is the
- name of the kernel device.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$links</option></term>
- <listitem>
- <para>A space-separated list of the current symlinks. The value is
- only set during a remove event or if an earlier rule assigned a value.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$root</option>, <option>%r</option></term>
- <listitem>
- <para>The udev_root value.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$sys</option>, <option>%S</option></term>
- <listitem>
- <para>The sysfs mount point.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$devnode</option>, <option>%N</option></term>
- <listitem>
- <para>The name of the device node.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>%%</option></term>
- <listitem>
- <para>The <literal>%</literal> character itself.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>$$</option></term>
- <listitem>
- <para>The <literal>$</literal> character itself.</para>
- </listitem>
- </varlistentry>
- </variablelist>
+ <term><literal>file</literal></term>
+ <listitem>
+ <para>Import a text file specified as the assigned value, the content
+ of which must be in environment key format.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>db</literal></term>
+ <listitem>
+ <para>Import a single property specified as the assigned value from the
+ current device database. This works only if the database is already populated
+ by an earlier event.</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 <literal>1</literal>.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>parent</literal></term>
+ <listitem>
+ <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 glob pattern matching used for
+ comparisons).</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>This can only be used for very short-running foreground tasks. For details see
+ <option>RUN</option>.</para>
+
+ <para>Note that multiple <varname>IMPORT{}</varname> keys may be specified in one rule, and
+ <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as
+ <literal>==</literal>. The key is true if the import is successful, unless <literal>!=</literal>
+ is used as the operator which causes the key to be true if the import failed.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>OPTIONS</varname></term>
+ <listitem>
+ <para>Rule and device options:</para>
+ <variablelist class='udev-directives'>
+ <varlistentry>
+ <term><option>link_priority=<replaceable>value</replaceable></option></term>
+ <listitem>
+ <para>Specify the priority of the created symlinks. Devices with higher
+ priorities overwrite existing symlinks of other devices. The default is 0.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>string_escape=<replaceable>none|replace</replaceable></option></term>
+ <listitem>
+ <para>Usually, control and other possibly unsafe characters are replaced
+ in strings used for device naming. The mode of replacement can be specified
+ with this option.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>static_node=</option></term>
+ <listitem>
+ <para>Apply the permissions specified in this rule to the
+ static device node with 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>
+ <term><option>watch</option></term>
+ <listitem>
+ <para>Watch the device node with inotify; when the node is
+ closed after being opened for writing, a change uevent is
+ synthesized.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>nowatch</option></term>
+ <listitem>
+ <para>Disable the watching of a device node with inotify.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>db_persist</option></term>
+ <listitem>
+ <para>Set the flag (sticky bit) on the udev database entry
+ of the event device. Device properties are then kept in the
+ database even when
+ <command>udevadm info --cleanup-db</command> is called.
+ This option can be useful in certain cases
+ (e.g. Device Mapper devices) for persisting device state
+ on the transition from initramfs.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>,
+ <varname>PROGRAM</varname>, <varname>OWNER</varname>,
+ <varname>GROUP</varname>, <varname>MODE</varname>, <varname>SECLABEL</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 being
+ processed. The available substitutions are:</para>
+ <variablelist class='udev-directives'>
+ <varlistentry>
+ <term><option>$kernel</option>, <option>%k</option></term>
+ <listitem>
+ <para>The kernel name for this device.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$number</option>, <option>%n</option></term>
+ <listitem>
+ <para>The kernel number for this device. For example, <literal>sda3</literal> has kernel number
+ 3.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$devpath</option>, <option>%p</option></term>
+ <listitem>
+ <para>The devpath of the device.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$id</option>, <option>%b</option></term>
+ <listitem>
+ <para>The name of the device matched while searching the devpath
+ upwards for <option>SUBSYSTEMS</option>, <option>KERNELS</option>,
+ <option>DRIVERS</option>, and <option>ATTRS</option>.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$driver</option></term>
+ <listitem>
+ <para>The driver name of the device matched while searching the
+ devpath upwards for <option>SUBSYSTEMS</option>,
+ <option>KERNELS</option>, <option>DRIVERS</option>, and
+ <option>ATTRS</option>.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term>
+ <listitem>
+ <para>The value of a sysfs attribute found at the device where
+ all keys of the rule have matched. If the matching device does not
+ have such an attribute, and a previous <option>KERNELS</option>,
+ <option>SUBSYSTEMS</option>, <option>DRIVERS</option>, or
+ <option>ATTRS</option> test selected a parent device, then the
+ attribute from that parent device is used.
+ </para>
+ <para>If the attribute is a symlink, the last element of the
+ symlink target is returned as the value.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term>
+ <listitem>
+ <para>A device property value.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$major</option>, <option>%M</option></term>
+ <listitem>
+ <para>The kernel major number for the device.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$minor</option>, <option>%m</option></term>
+ <listitem>
+ <para>The kernel minor number for the device.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$result</option>, <option>%c</option></term>
+ <listitem>
+ <para>The string returned by the external program requested with
+ <varname>PROGRAM</varname>.
+ A single part of the string, separated by a space character, may be selected
+ 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>
+ <term><option>$parent</option>, <option>%P</option></term>
+ <listitem>
+ <para>The node name of the parent device.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$name</option></term>
+ <listitem>
+ <para>The current name of the device. If not changed by a rule, it is the
+ name of the kernel device.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$links</option></term>
+ <listitem>
+ <para>A space-separated list of the current symlinks. The value is
+ only set during a remove event or if an earlier rule assigned a value.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$root</option>, <option>%r</option></term>
+ <listitem>
+ <para>The udev_root value.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$sys</option>, <option>%S</option></term>
+ <listitem>
+ <para>The sysfs mount point.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$devnode</option>, <option>%N</option></term>
+ <listitem>
+ <para>The name of the device node.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>%%</option></term>
+ <listitem>
+ <para>The <literal>%</literal> character itself.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>$$</option></term>
+ <listitem>
+ <para>The <literal>$</literal> character itself.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect2>
</refsect1>
<refsect1>
projects / thirdparty / systemd.git / commitdiff
