<para>Usually udev runs as <citerefentry><refentrytitle>udevd</refentrytitle>
<manvolnum>8</manvolnum></citerefentry> and receives uevents directly from the
- kernel if a device is added or removed form the system.</para>
+ kernel if a device is added or removed from the system.</para>
<para>If udev receives a device event, it matches its configured rules
against the available device attributes provided in sysfs to identify the device.
- Rules that match, may provide additional device information or specify a device
+ Rules that match may provide additional device information or specify a device
node name and multiple symlink names and instruct udev to run additional programs
as part of the device event handling.</para>
</refsect1>
value in the configuration file. Every line in the rules file contains at least
one key value pair. There are two kind of keys, match and assignment keys.
If all match keys are matching against its value, the rule gets applied and the
- assign keys get the specified value assigned. A matching rule may specify the
- name of the device node, add a symlink pointing to the node, or run a specified
- program as part of the event handling. If no matching rule is found, the default
- device node name is used.</para>
+ assign keys get the specified value assigned.</para>
- <para>A rule may consists of a list of one or more key value pairs separated by
+ <para>A matching rule may specify the name of the device node, add a symlink
+ pointing to the node, or run a specified program as part of the event handling.
+ If no matching rule is found, the default device node name is used.</para>
+
+ <para>A rule may consist of a list of one or more key value pairs separated by
a comma. Each key has a distinct operation, depending on the used operator. Valid
operators are:</para>
<variablelist>
</varlistentry>
</variablelist>
- <para>The following key names can be used to match against device properties:</para>
+ <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>
<varlistentry>
<term><option>ACTION</option></term>
</varlistentry>
<varlistentry>
- <term><option>KERNEL</option></term>
+ <term><option>DEVPATH</option></term>
<listitem>
- <para>Match the name of the device.</para>
+ <para>Match the devpath of the event device.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>DEVPATH</option></term>
+ <term><option>KERNEL</option></term>
<listitem>
- <para>Match the devpath of the device.</para>
+ <para>Match the name of the event device.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>SUBSYSTEM</option></term>
<listitem>
- <para>Match the subsystem of the device.</para>
+ <para>Match the subsystem of the event device.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>DRIVER</option></term>
+ <listitem>
+ <para>Match the driver name of the event device. Only set 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>
+ <listitem>
+ <para>Match sysfs attribute values of the event device. Up to five
+ <option>ATTR</option> keys can be specified per rule. Trailing
+ whitespace in the attribute values is ignored, if the specified match
+ value does not contain trailing whitespace itself. Depending on the type
+ of operator, this key is also used to set the value of a sysfs attribute.
+ </para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>BUS</option></term>
+ <term><option>KERNELS</option></term>
<listitem>
- <para>Search the devpath upwards for a matching device subsystem name.</para>
+ <para>Search the devpath upwards for a matching device name.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>DRIVER</option></term>
+ <term><option>SUBSYSTEMS</option></term>
<listitem>
- <para>Search the devpath upwards for a matching device driver name.</para>
+ <para>Search the devpath upwards for a matching device subsystem name.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>ID</option></term>
+ <term><option>DRIVERS</option></term>
<listitem>
- <para>Search the devpath upwards for a matching device name.</para>
+ <para>Search the devpath upwards for a matching device driver name.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>SYSFS{<replaceable>filename</replaceable>}</option></term>
+ <term><option>ATTRS{<replaceable>filename</replaceable>}</option></term>
<listitem>
<para>Search the devpath upwards for a device with matching sysfs attribute values.
- Up to five <option>SYSFS</option> keys can be specified per rule. All attributes
+ Up to five <option>ATTRS</option> keys can be specified per rule, but all of them
must match on the same device. Trailing whitespace in the attribute values is ignored,
if the specified match value does not contain trailing whitespace itself.</para>
</listitem>
<term><option>ENV{<replaceable>key</replaceable>}</option></term>
<listitem>
<para>Match against the value of an environment variable. Up to five <option>ENV</option>
- keys can be specified per rule. This key can also be used to export a variable to
- the environment.</para>
+ keys can be specified per rule. Depending on the type of operator, this key is also used
+ to export a variable to the environment.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>TEST{<replaceable>octal mode mask</replaceable>}</option></term>
+ <listitem>
+ <para>Test the existence of a file. An octal mode mask can be specified
+ if needed.</para>
</listitem>
</varlistentry>
<term><option>PROGRAM</option></term>
<listitem>
<para>Execute external program. The key is true, if the program returns
- without exit code zero. The whole event environment is available to the
- executed program. The program's output printed to stdout is available for
+ with exit code zero. The whole event environment is available to the
+ executed program. The program's output printed to stdout, is available in
the RESULT key.</para>
</listitem>
</varlistentry>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>ATTR{<replaceable>key</replaceable>}</option></term>
+ <listitem>
+ <para>The value that should be written to a sysfs attribute of the
+ event device. Depending on the type of operator, this key is also
+ used to match against the value of a sysfs attribute.</para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>ENV{<replaceable>key</replaceable>}</option></term>
<listitem>
- <para>Export a variable to the environment. This key can also be used to match
- against an environment variable.</para>
+ <para>Export a variable to the environment. Depending on the type of operator,
+ this key is also to match against an environment variable.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>IMPORT{<replaceable>type</replaceable>}</option></term>
<listitem>
- <para>Import the printed result or the value of a file in environment key
- format into the event environment. <option>program</option> will execute an
- external program and read its output. <option>file</option> will import a
- text file. If no option is given, udev will determine it from the executable
- bit of of the file permissions.</para>
+ <para>Import a set of variables into the event environment,
+ depending on <replaceable>type</replaceable>:</para>
+ <variablelist>
+ <varlistentry>
+ <term><option>program</option></term>
+ <listitem>
+ <para>Execute an external program specified as the assigned value and
+ import its output, which must be in environment key format.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>file</option></term>
+ <listitem>
+ <para>Import a text file specified as the assigned value, which must be in
+ environment key format.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>parent</option></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-style pattern matching used for
+ comparisons).</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <para>If no option is given, udev will choose between <option>program</option>
+ and <option>file</option> based on the executable bit of the file
+ permissions.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>OPTIONS</option></term>
<listitem>
- <para><option>last_rule</option> stops further rules application. No later rules
- will have any effect.
- <option>ignore_device</option> will ignore this event completely.
- <option>ignore_remove</option> will ignore any later remove event for this
- device. This may be useful as a workaround for broken device drivers.
- <option>all_partitions</option> will create the device nodes for all available
- partitions of a block device. This may be useful for removable media devices where
- media changes are not detected.</para>
+ <para>Rule and device options:</para>
+ <variablelist>
+ <varlistentry>
+ <term><option>last_rule</option></term>
+ <listitem>
+ <para>Stops further rules application. No later rules will have
+ any effect.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>ignore_device</option></term>
+ <listitem>
+ <para>Ignore this event completely.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>ignore_remove</option></term>
+ <listitem>
+ <para>Ignore any later remove event for this device. This may be useful
+ as a workaround for broken device drivers.</para>
+ </listitem>
+ </varlistentry>
+ <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.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>all_partitions</option></term>
+ <listitem>
+ <para>Create the device nodes for all available partitions of a block device.
+ This may be useful for removable media devices where media changes are not
+ detected.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
</listitem>
</varlistentry>
</variablelist>
<term><option>$id</option>, <option>%b</option></term>
<listitem>
<para>The name of the device matched while searching the devpath upwards for
- <option>BUS</option>, <option>ID</option> <option>DRIVER</option> and <option>SYSFS</option>.
+ <option>SUBSYSTEMS</option>, <option>KERNELS</option>, <option>DRIVERS</option> and <option>ATTRS</option>.
</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>$sysfs{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term>
+ <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term>
<listitem>
- <para>The value of a sysfs attribute found at the current or a parent device.</para>
+ <para>The value of a sysfs attribute found at the device, where
+ all keys of the rule have matched. If the matching device does not have
+ such an attribute, all devices along the chain of parents are searched
+ for a matching attribute.
+ If the attribute is a symlink, the last element of the symlink target is
+ returned as the value.</para>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
- <term><option>$minor</option> <option>%m</option></term>
+ <term><option>$minor</option>, <option>%m</option></term>
<listitem>
<para>The kernel minor number for the device.</para>
</listitem>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>$sys</option>, <option>%S</option></term>
+ <listitem>
+ <para>The sysfs mount point.</para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>$tempnode</option>, <option>%N</option></term>
<listitem>
~ianmdlvl / elogind.git / blobdiff