<refentry>
<refentryinfo>
<title>udev</title>
- <date>August 2005</date>
<productname>udev</productname>
</refentryinfo>
<refmeta>
<refentrytitle>udev</refentrytitle>
<manvolnum>7</manvolnum>
- <refmiscinfo class="version"></refmiscinfo>
</refmeta>
<refnamediv>
the custom rules directory <filename>/etc/udev/rules.d/</filename>
and the temporary rules directory <filename>/dev/.udev/rules.d/</filename>.
All rule files are sorted and processed in lexical order, regardless
- in which of these directories they live. Every line in the rules file contains at least
- one key value pair. There are two kind of keys, match and assignment keys.
+ in which of these directories they live.</para>
+
+ <para>Rule files are required to have a unique name, duplicate file names
+ are ignored. Files in <filename>/etc/udev/rules.d/</filename> have precedence
+ over files with the same name in <filename>/lib/udev/rules.d/</filename>. This
+ can be used to ignore a default rules file if needed.</para>
+
+ <para>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.</para>
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
+ <para>A rule consists 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>
<term><option>!=</option></term>
<listitem>
- <para>Compare for non-equality.</para>
+ <para>Compare for inequality.</para>
</listitem>
</varlistentry>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>SYMLINK</option></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><option>SUBSYSTEM</option></term>
<listitem>
<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
+ <para>Match sysfs attribute values of the event device. 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.
+ value does not contain trailing whitespace itself.
</para>
</listitem>
</varlistentry>
<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>ATTRS</option> keys can be specified per rule, but all of them
+ If multiple <option>ATTRS</option> matches are specified, 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>
<varlistentry>
<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. Depending on the type of operator, this key is also used
- to export a variable to the environment.</para>
+ <para>Match against a device property value.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>TAG</option></term>
+ <listitem>
+ <para>Match against a device tag.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>PROGRAM</option></term>
<listitem>
- <para>Execute external program. The key is true, if the program returns
- 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>
+ <para>Execute a program. 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 output printed to
+ stdout, is available in the RESULT key.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>NAME</option></term>
<listitem>
- <para>The name of the node to be created, or the name the network interface
- should be renamed to. Only one rule can set the node name, all later rules with
- a NAME key will be ignored.</para>
+ <para>The name, a network interface should be renamed to, or the name
+ a device node should be named. Usually the kernel provides the defined
+ node name, or even creates and removes the node before udev receives
+ any event. Changing the node name from the kernel's default may result
+ in unexpected behavior and is not supported. Udev is only expected to
+ handle device node permissions and to create additional symlinks, which
+ do not conflict with the kernel device node names.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>SYMLINK</option></term>
<listitem>
- <para>The name of a symlink targeting the node. Every matching rule can add
- this value to the list of symlinks to be created along with the device node.
+ <para>The name of a symlink targeting the node. Every matching rule will add
+ this value to the list of symlinks to be created along with the device node.
Multiple symlinks may be specified by separating the names by the space
- character.</para>
+ character. In case multiple devices claim the same name, the link will
+ always point to the device with the highest link_priority. If the current device
+ goes away, the links will be re-evaluated and the device with the next highest
+ link_priority will own the link. If no link_priority is specified, the order
+ of the devices, and which of them will own the link, is undefined. Claiming
+ the same name for a node and links may result in unexpected behavior and is
+ not supported.
+ </para>
</listitem>
</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>
+ event device.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>ENV{<replaceable>key</replaceable>}</option></term>
<listitem>
- <para>Export a variable to the environment. Depending on the type of operator,
- this key is also to match against an environment variable.</para>
+ <para>Set a device property value. Property names with a leading '.'
+ are not stored in the database or exported to external tool or events.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>TAG</option></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>
device. This can only be used for very short running tasks. Running an
event process for a long period of time may block all further events for
this or a dependent device. Long running tasks need to be immediately
- detached from the event process itself.</para>
- <para>If the specifiefd string starts with
+ detached from the event process itself. If the option
+ <option>RUN{<replaceable>fail_event_on_error</replaceable>}</option> is
+ specified, and the executed program returns non-zero, the event will be
+ marked as failed for a possible later handling.</para>
+ <para>If no path is given, the program must be in
+ <filename>/lib/udev</filename>, otherwise the full path must be
+ specified.</para>
+ <para>If the specified string starts with
<option>socket:<replaceable>path</replaceable></option>, all current event
values will be passed to the specified socket, as a message in the same
format the kernel sends an uevent. If the first character of the specified path
is an @ character, an abstract namespace socket is used, instead of an existing
socket file.</para>
+ <para>Program name and arguments are separated with spaces. To
+ include spaces in an argument, use single quotes. Please note
+ that this does not run through a shell.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>IMPORT{<replaceable>type</replaceable>}</option></term>
<listitem>
- <para>Import a set of variables into the event environment,
+ <para>Import a set of variables as device properties,
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>
+ import its output, which must be in environment key
+ format. Path specification, command/argument separation,
+ and quoting work like in <option>RUN</option>.</para>
</listitem>
</varlistentry>
<varlistentry>
environment key format.</para>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>db</option></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><option>parent</option></term>
<listitem>
<varlistentry>
<term><option>WAIT_FOR</option></term>
<listitem>
- <para>Wait for a file to become available.</para>
+ <para>Wait for a file to become available or until a 10
+ seconds timeout expires.</para>
</listitem>
</varlistentry>
<listitem>
<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>Do not remove the device node when the device goes away. 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>
priorities overwrite existing symlinks of other devices. The default is 0.</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>
<varlistentry>
<term><option>event_timeout=</option></term>
<listitem>
with this option.</para>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>watch</option></term>
+ <listitem>
+ <para>Watch the device node with inotify, when closed after being opened for
+ writing, a change uevent will be synthesised.</para>
+ </listitem>
+ </varlistentry>
</variablelist>
</listitem>
</varlistentry>
<option>OWNER</option>, <option>GROUP</option>, <option>MODE</option> and <option>RUN</option>
fields support simple printf-like string substitutions. The <option>RUN</option>
format chars gets applied after all rules have been processed, right before the program
- is executed. It allows the use of the complete environment set by earlier matching
+ is executed. It allows the use of device properties set by earlier matching
rules. For all other fields, substitutions are applied while the individual rule is
being processed. The available substitutions are:</para>
<variablelist>
<varlistentry>
<term><option>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term>
<listitem>
- <para>The value of an environment variable.</para>
+ <para>A device property value.</para>
</listitem>
</varlistentry>
</listitem>
</varlistentry>
</variablelist>
- <para>The count of characters to be substituted may be limited by specifying
- the format length value. For example, '%3s{file}' will only
- insert the first three characters of the sysfs attribute</para>
</refsect2>
</refsect1>
~ianmdlvl / elogind.git / blobdiff