<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>Configuration</title>
- <para>udev configuration files are placed in <filename>/etc/udev</filename>
- and <filename>/usr/lib/udev</filename>. All empty lines or lines beginning with
- '#' are ignored.</para>
-
- <refsect2><title>Configuration file</title>
- <para>udev expects its main configuration file at <filename>/etc/udev/udev.conf</filename>.
- It consists of a set of variables allowing the user to override default udev values.
- The following variables can be set:</para>
- <variablelist>
- <varlistentry>
- <term><option>udev_log</option></term>
- <listitem>
- <para>The logging priority. Valid values are the numerical syslog priorities
- or their textual representations: <option>err</option>, <option>info</option>
- and <option>debug</option>.</para>
- </listitem>
- </varlistentry>
- </variablelist>
- </refsect2>
-
- <refsect2><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
+ over files with the same name in <filename>/usr/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>
+ <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>,
+ 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.
- There are two kind of keys: match and assignment.
- If all match keys are matching against its value, the rule gets applied and the
- assignment keys get the specified value assigned.</para>
+ 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>
<para>A matching rule may rename a network interface, add symlinks
pointing to the device node, or run a specified program as part of
operators are:</para>
<variablelist>
<varlistentry>
- <term><option>==</option></term>
+ <term><literal>==</literal></term>
<listitem>
<para>Compare for equality.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>!=</option></term>
+ <term><literal>!=</literal></term>
<listitem>
<para>Compare for inequality.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>=</option></term>
+ <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>
</varlistentry>
<varlistentry>
- <term><option>+=</option></term>
+ <term><literal>+=</literal></term>
<listitem>
<para>Add the value to a key that holds a list of entries.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>:=</option></term>
+ <term><literal>:=</literal></term>
<listitem>
<para>Assign a value to a key finally; disallow any later changes.</para>
</listitem>
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>
+ <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
successfully. The device properties are made available to the
- 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>
+ executed program in the environment. The program's standard ouput
+ 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>
</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>
+ <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-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><option>*</option></term>
+ <term><literal>*</literal></term>
<listitem>
<para>Matches zero or more characters.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>?</option></term>
+ <term><literal>?</literal></term>
<listitem>
<para>Matches any single character.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>[]</option></term>
+ <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.
- 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>
+ 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>
</variablelist>
<para>The following keys can get values assigned:</para>
- <variablelist>
+ <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
- can not be changed by udev, only additional symlinks can be created.</para>
+ cannot be changed by udev, only additional symlinks can be created.</para>
</listitem>
</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. 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. Also, symlink names must
- never conflict with the kernel's default device node names, as that would
- result in unpredictable behavior.
+ 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><option>OWNER, GROUP, 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>
+ external tools (run by, for example, the <varname>PROGRAM</varname>
+ 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</option></term>
+ <term><varname>RUN{<replaceable>type</replaceable>}</varname></term>
<listitem>
- <para>Add a program to the list of programs to be executed for a specific
- device.</para>
- <para>If no absolute path is given, the program is expected to live in
- /usr/lib/udev, otherwise the absolute path must be specified. The program
- name and following arguments are separated by spaces. Single quotes can
- be used to specify arguments with spaces.</para>
+ <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>
+ <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>Starting daemons or other long running processes is not appropriate
+ <para>Starting daemons or other long-running processes is not appropriate
for udev; the forked processes, detached or not, will be unconditionally
killed after the event handling has finished.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>LABEL</option></term>
+ <term><varname>LABEL</varname></term>
<listitem>
- <para>A named label to which a GOTO may jump.</para>
+ <para>A named label to which a <varname>GOTO</varname> 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>
+ <para>Jumps to the next <varname>LABEL</varname> 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 <replaceable>type</replaceable>:</para>
+ depending on <literal>type</literal>:</para>
<variablelist>
<varlistentry>
- <term><option>program</option></term>
+ <term><literal>program</literal></term>
<listitem>
<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><option>file</option></term>
+ <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><option>db</option></term>
+ <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
</listitem>
</varlistentry>
<varlistentry>
- <term><option>cmdline</option></term>
+ <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>
- <term><option>parent</option></term>
+ <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-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>
+ <variablelist class='udev-directives'>
<varlistentry>
<term><option>link_priority=<replaceable>value</replaceable></option></term>
<listitem>
<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. 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>
+ <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>
+ <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>
</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>
- 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>
+ <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 being
+ processed. The available substitutions are:</para>
+ <variablelist class='udev-directives'>
<varlistentry>
<term><option>$kernel</option>, <option>%k</option></term>
<listitem>
<varlistentry>
<term><option>$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>
<varlistentry>
<term><option>$id</option>, <option>%b</option></term>
<listitem>
- <para>The name of the device matched while searching the devpath upwards for
- <option>SUBSYSTEMS</option>, <option>KERNELS</option>, <option>DRIVERS</option> and <option>ATTRS</option>.
+ <para>The name of the device matched while searching the devpath
+ upwards for <option>SUBSYSTEMS</option>, <option>KERNELS</option>,
+ <option>DRIVERS</option>, and <option>ATTRS</option>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>$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>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>
<term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term>
<listitem>
<para>The value of a sysfs attribute found at the device where
- all keys of the rule have matched. If the matching device does not have
- such an attribute, and a previous KERNELS, SUBSYSTEMS, DRIVERS, or
- ATTRS test selected a parent device, then the attribute from that
- parent device is used.</para>
- <para>If the attribute is a symlink, the last element of the symlink target is
- returned as the value.</para>
+ all keys of the rule have matched. If the matching device does not
+ have such an attribute, and a previous <option>KERNELS</option>,
+ <option>SUBSYSTEMS</option>, <option>DRIVERS</option>, or
+ <option>ATTRS</option> test selected a parent device, then the
+ attribute from that parent device is used.
+ </para>
+ <para>If the attribute is a symlink, the last element of the
+ symlink target is returned as the value.
+ </para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>$result</option>, <option>%c</option></term>
<listitem>
- <para>The string returned by the external program requested with PROGRAM.
+ <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: <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>
<term><option>%%</option></term>
<listitem>
- <para>The '%' character itself.</para>
+ <para>The <literal>%</literal> character itself.</para>
</listitem>
</varlistentry>
<varlistentry>
<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>/usr/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>/usr/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>Network Link Configuration</title>
+ <para>Network link configuration is performed by the <literal>net_setup_link</literal>
+ udev builtin.</para>
+
+ <para>The link files are read from the files located in the
+ system network directory <filename>/usr/lib/systemd/network</filename>,
+ the volatile runtime network directory <filename>/run/systemd/network</filename>
+ and the local administration network directory <filename>/etc/systemd/network</filename>.
+ Link files must have the extension <filename>.link</filename>; other extensions are ignored.
+ All link 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>/usr/lib</filename>. This can be
+ used to override a system-supplied link file with a local file if needed;
+ a symlink in <filename>/etc</filename> with the same name as a link file in
+ <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>,
+ disables the link file entirely.</para>
+
+ <para>The link file contains a <literal>[Match]</literal> section, which
+ determines if a given link file may be applied to a given device; and a
+ <literal>[Link]</literal> section specifying how the device should be
+ configured. The first (in lexical order) of the link files that matches
+ a given device is applied.</para>
+
+ <para>A link file is said to match a device if each of the entries in the
+ <literal>[Match]</literal> section matches, or if the section is empty.
+ The following keys are accepted:</para>
+
+ <variablelist class='network-directives'>
+ <varlistentry>
+ <term><varname>MACAddress</varname></term>
+ <listitem>
+ <para>The hardware address.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>Path</varname></term>
+ <listitem>
+ <para>The persistent path, as exposed by the udev property <literal>ID_PATH</literal>.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>Driver</varname></term>
+ <listitem>
+ <para>The driver currently bound to the device, as exposed by the udev property <literal>DRIVER</literal>.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>Type</varname></term>
+ <listitem>
+ <para>The device type, as exposed by the udev property <literal>DEVTYPE</literal>.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>The <literal>[Link]</literal> section accepts the following keys:</para>
+
+ <variablelist class='network-directives'>
+ <varlistentry>
+ <term><varname>Description</varname></term>
+ <listitem>
+ <para>A description of the device.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>Alias</varname></term>
+ <listitem>
+ <para>The <literal>ifalias</literal> is set to this value.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>MACAddressPolicy</varname></term>
+ <listitem>
+ <para>The policy by which the MAC address should be set. The
+ available policies are:
+ </para>
+ <variablelist>
+ <varlistentry>
+ <term><literal>persistent</literal></term>
+ <listitem>
+ <para>If the hardware has a persistent MAC address, as most
+ hardware should, and this is used by the kernel, nothing is
+ done. Otherwise, a new MAC address is generated which is
+ guaranteed to be the same on every boot for the given
+ machine and the given device, but which is otherwise random.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>random</literal></term>
+ <listitem>
+ <para>If the kernel is using a random MAC address, nothing is
+ done. Otherwise, a new address is randomly generated each
+ time the device appears, typically at boot.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>MACAddress</varname></term>
+ <listitem>
+ <para>The MAC address to use, if no <literal>MACAddressPolicy</literal>
+ is specified.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>NamePolicy</varname></term>
+ <listitem>
+ <para>An ordered, space-separated list of policies by which the
+ interface name should be set. <literal>NamePolicy</literal> may
+ be disabeled by specifying <literal>net.ifnames=0</literal> on the
+ kernel commandline. Each of the policies may fail, and the first
+ successfull one is used. The name is not set directly, but
+ is exported to udev as the property <literal>ID_NET_NAME</literal>,
+ which is, by default, used by a udev rule to set
+ <literal>NAME</literal>. The available policies are:
+ </para>
+ <variablelist>
+ <varlistentry>
+ <term><literal>onboard</literal></term>
+ <listitem>
+ <para>The name is set based on information given by the
+ firmware for on-board devices, as exported by the udev
+ property <literal>ID_NET_NAME_ONBOARD</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>slot</literal></term>
+ <listitem>
+ <para>The name is set based on information given by the
+ firmware for hot-plug devices, as exported by the udev
+ property <literal>ID_NET_NAME_SLOT</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>path</literal></term>
+ <listitem>
+ <para>The name is set based on the device's physical location,
+ as exported by the udev property
+ <literal>ID_NET_NAME_PATH</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>mac</literal></term>
+ <listitem>
+ <para>The name is set based on the device's persistent MAC
+ address, as exported by the udev property
+ <literal>ID_NET_NAME_MAC</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>Name</varname></term>
+ <listitem>
+ <para>The interface name to use in case all the policies specified
+ in <literal>NamePolicy</literal> fail, or in case
+ <literal>NamePolicy</literal> is missing or disabled.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>MTU</varname></term>
+ <listitem>
+ <para>The MTU to set for the device.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>SpeedMBytes</varname></term>
+ <listitem>
+ <para>The speed to set for the device.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>Duplex</varname></term>
+ <listitem>
+ <para>The duplex mode to set for the device. The accepted values
+ are <literal>half</literal> and <literal>full</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>WakeOnLan</varname></term>
+ <listitem>
+ <para>The Wake-on-LAN policy to set for the device. The supported
+ values are:
+ </para>
+ <variablelist>
+ <varlistentry>
+ <term><literal>phy</literal></term>
+ <listitem>
+ <para>Wake on PHY activity.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>magic</literal></term>
+ <listitem>
+ <para>Wake on receipt of a magic packet.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><literal>off</literal></term>
+ <listitem>
+ <para>Never wake.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
</listitem>
</varlistentry>
</variablelist>
- </refsect2>
</refsect1>
<refsect1>
<title>See Also</title>
- <para><citerefentry>
+ <para>
+ <citerefentry>
<refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum>
- </citerefentry></para>
+ </citerefentry>
+ </para>
</refsect1>
</refentry>
~ianmdlvl / elogind.git / blobdiff