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All udev state is kept in /$udev_root/.udev/ now. No option to configure that anymore, it will always be there. Signed-off-by: Kay Sievers <kay.sievers@suse.de>
538 lines
22 KiB
XML
538 lines
22 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<article>
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<articleinfo>
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<title>xmlto</title>
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<author>
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<firstname>Kay</firstname>
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<surname>Sievers</surname>
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<email>kay.sievers@vrfy.org</email>
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</author>
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<copyright>
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<year>2005</year>
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<holder>Kay Sievers</holder>
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</copyright>
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</articleinfo>
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<section>
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<title>udev</title>
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<refentry>
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<refentryinfo>
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<title>udev</title>
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<date>August 2005</date>
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<productname>udev</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>udev</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>udev</refname>
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<refpurpose>dynamic device management</refpurpose>
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</refnamediv>
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<refsect1><title>DESCRIPTION</title>
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<para>udev provides a dynamic device directory containing only the files for
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actually present devices. It creates or removes device node files in the
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<filename>/dev</filename> directory, or it renames network interfaces.</para>
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<para>Usually udev runs as <citerefentry><refentrytitle>udevd</refentrytitle>
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<manvolnum>8</manvolnum></citerefentry> and receives uevents directly from the
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kernel if a device is added or removed form the system. The program
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<command>udev</command> itself may be used as an event handler in situations,
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where running the daemon is not appropriate, like in initramfs.</para>
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<para>If udev receives a device event, it matches its configured rules
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against the available device attributes provided in sysfs to identify the device.
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Rules that match, may provide additional device information or specify a device
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node name and multiple symlink names and instruct udev to run additional programs
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as part of the device event handling.</para>
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</refsect1>
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<refsect1><title>CONFIGURATION</title>
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<para>All udev configuration files are placed in <filename>/etc/udev/*</filename>.
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Every file consist of a set of lines of text. All empty lines or lines beginning
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with '#' will be ignored.</para>
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<refsect2><title>Configuration file</title>
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<para>udev expects its main configuration file at <filename>/etc/udev/udev.conf</filename>.
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It consists of a set of variables allowing the user to override default udev values.
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The following variables can be set:</para>
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<variablelist>
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<varlistentry>
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<term><option>udev_root</option></term>
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<listitem>
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<para>Specifies where to place the device nodes in the filesystem.
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The default value is <filename>/dev</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>udev_rules</option></term>
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<listitem>
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<para>The name of the udev rules file or directory to look for files
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with the suffix <filename>.rules</filename>. Multiple rule files are
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read in lexical order. The default value is
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<filename>/etc/udev/rules.d</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>udev_log</option></term>
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<listitem>
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<para>The logging priority. Valid values are the numerical syslog priorities
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or their textual representations: <option>err</option>, <option>info</option>
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and <option>debug</option>.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect2>
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<refsect2><title>Rules files</title>
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<para>The udev rules are read from the files located in the
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<filename>/etc/udev/rules.d</filename> directory or at the location specified
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value in the configuraton file. Every line in the rules file contains at least
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one key value pair. There are two kind of keys, match and assignement keys.
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If all match keys are matching against its value, the rule gets applied and the
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assign keys get the specified value assigned. A matching rule may specify the
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name of the device node, add a symlink pointing to the node, or run a specified
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program as part of the event handling. If no matching rule is found, the default
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device node name is used.</para>
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<para>A rule may consists of a list of one or more key value pairs separated by
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a comma. Each key has a distinct operation, depending on the used operator. Valid
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operators are:</para>
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<variablelist>
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<varlistentry>
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<term><option>==</option></term>
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<listitem>
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<para>Compare for equality.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>!=</option></term>
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<listitem>
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<para>Compare for non-equality.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>=</option></term>
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<listitem>
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<para>Asign a value to a key. Keys that represent a list, are reset
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and only this single value is assigned.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>+=</option></term>
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<listitem>
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<para>Add the value to a key that holds a list of entries.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>:=</option></term>
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<listitem>
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<para>Assign a value to a key finally; disallow any later changes,
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which may be used to prevent changes by any later rules.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>The following key names can be used to match against device properties:</para>
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<variablelist>
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<varlistentry>
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<term><option>ACTION</option></term>
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<listitem>
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<para>Match the kernel action name.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>KERNEL</option></term>
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<listitem>
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<para>Match the kernel device name</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>DEVPATH</option></term>
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<listitem>
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<para>Match the kernel devpath.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>SUBSYSTEM</option></term>
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<listitem>
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<para>Match the kernel subsystem name</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>BUS</option></term>
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<listitem>
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<para>Match the typ of bus the device is connected to.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>DRIVER</option></term>
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<listitem>
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<para>Match the kernel driver name.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>ID</option></term>
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<listitem>
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<para>Match the device number on the bus.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>ENV{<replaceable>key</replaceable>}</option></term>
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<listitem>
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<para>Match against the value of an environment key. Depending on
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the specified operation, this key is also used as a assignment.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>SYSFS{<replaceable>filename</replaceable>}</option></term>
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<listitem>
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<para>Match the sysfs attribute value. Up to five values can be specified.
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Trailing whitespace is ignored, if the specified match value does not contain
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trailing whitespace itself.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>PROGRAM</option></term>
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<listitem>
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<para>Execute external program. The key is true, if the program returns
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without exit code zero. The whole event environment is available to the
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executed program. The program's output printed to stdout is available for
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the RESULT key.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>RESULT</option></term>
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<listitem>
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<para>Match the returned string of the last PROGRAM call. This key can
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be used in the same or in any later rule after a PROGRAM call.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>Most of the fields support a shell style pattern matching. The following
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pattern characters are supported:</para>
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<variablelist>
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<varlistentry>
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<term><option>*</option></term>
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<listitem>
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<para>Matches zero, or any number of characters.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>?</option></term>
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<listitem>
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<para>Matches any single character.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>[]</option></term>
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<listitem>
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<para>Matches any single character specified within the brackets.
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example, the pattern string 'tty[SR]' would match either 'ttyS' or 'ttyR'.
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Ranges are also supported within this match with the '-' character.
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For example, to match on the range of all digits, the pattern [0-9] would
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be used. If the first character following the '[' is a '!', any characters
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not enclosed are matched.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>The following keys can get values assigned:</para>
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<variablelist>
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<varlistentry>
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<term><option>NAME</option></term>
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<listitem>
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<para>The name of the node to be created, or the name, the network interface
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should be renamed to. Only one rule can set the a name, all later rules with
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a NAME key will be ignored.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>SYMLINK</option></term>
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<listitem>
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<para>The name of a symlink targeting the node. Every matching rule can add
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this value to the list of symlinks to be created along with the device node.
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Multiple symlinks may be specified by separating the names by the space
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character.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>OWNER, GROUP, MODE</option></term>
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<listitem>
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<para>The permissions for the device node. Every specified value over writes
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the compiled-in default value.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>ENV{<replaceable>key</replaceable>}</option></term>
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<listitem>
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<para>Export the key to the environment. Depending on the specified
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operation, this key is also used as a match.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>RUN</option></term>
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<listitem>
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<para>Add a program to the list of programs to be executed for a specific
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device.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>LABEL</option></term>
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<listitem>
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<para>Named label where a GOTO can jump to.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>GOTO</option></term>
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<listitem>
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<para>Jumps to the next LABEL with a matching gname</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>IMPORT{<replaceable>type</replaceable>}</option></term>
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<listitem>
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<para>Import the printed result or the content of a file in environment key
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format into the event environment. <option>program</option> will execute an
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external program and read its output. <option>file</option> will inport a
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text file. If no option is given, udev will determine it from the executable
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bit of of the file permissions.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>WAIT_FOR_SYSFS</option></term>
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<listitem>
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<para>Wait for the specified sysfs file of the device to be created. May be used
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to fight agains timing issues wth the kernel.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>OPTIONS</option></term>
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<listitem>
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<para><option>last_rule</option> stops further rules application. No later rules
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will have any effect.
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<option>ignore_device</option> will ignore this event completely.
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<option>ignore_remove</option> will ignore any later remove event for this
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device. This may be useful as a workaround for broken device drivers.
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<option>all_partitions</option> will create device nodes for all available partitions of
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a block device. This may be useful for removable media.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>The <option>NAME</option>, <option>SYMLINK</option>, <option>PROGRAM</option>,
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<option>OWNER</option> and <option>GROUP</option> fields support simple
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printf-like string substitutions:</para>
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<variablelist>
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<varlistentry>
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<term><option>%k</option>, <option>$kernel</option></term>
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<listitem>
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<para>The kernel name for this device.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%b</option>, <option>$id</option></term>
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<listitem>
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<para>The kernel bus id for this device.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%n</option>, <option>$number</option></term>
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<listitem>
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<para>The kernel number for this device. For example, 'sda3' has
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kernel number of '3'</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%p</option>, <option>$devpath</option></term>
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<listitem>
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<para>The devpath of the device.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%s{<replaceable>file</replaceable>}</option>, <option>$sysfs{<replaceable>file</replaceable>}</option></term>
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<listitem>
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<para>The content of a sysfs attribute.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%e{<replaceable>key</replaceable>}</option>, <option>$env{<replaceable>key</replaceable>}</option></term>
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<listitem>
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<para>The value of an environment variable.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%m</option>, <option>$major</option></term>
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<listitem>
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<para>The kernel major number for the device.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%M</option> <option>$minor</option></term>
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<listitem>
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<para>The kernel minor number for the device.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%c</option>, <option>$result</option></term>
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<listitem>
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<para>The string returned by the external program requested with PROGRAM.
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A single part of the string, separated by a space character may be selected
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by specifying the part number as an attribute: <option>%c{N}</option>.
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If the number is followed by the '+' char this part plus all remaining parts
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of the result string are substituted: <option>%c{N+}</option></para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%e</option>, <option>$enum</option></term>
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<listitem>
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<para>If a device node already exists with the name, the smallest next free
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number is used. This can be used to create compatibility symlinks and enumerate
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devices of the same type originating from different kernel subsystems.</para>
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<para>Note: The use of the enumeration facility is unreliable for events that
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request a number at the same time. The use of enumerations in todays setups
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where devices can come and go at any time is not recommended.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%P</option>, <option>$parent</option></term>
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<listitem>
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<para>The node name of the parent device.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%r</option>, <option>$root</option></term>
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<listitem>
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<para>The udev_root value.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%N</option>, <option>$tempnode</option></term>
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<listitem>
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<para>The name of a created temporary device node to provide access to
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the device from a external program before the real node is created.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>%%</option></term>
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<listitem>
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<para>The '%' character itself.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>$$</option></term>
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<listitem>
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<para>The '$' character itself.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>The count of characters to be substituted may be limited by specifying
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the format length value. For example, '%3s{file}' will only
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insert the first three characters of the sysfs attribute</para>
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</refsect2>
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</refsect1>
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<refsect1><title>ENVIRONMENT</title>
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<variablelist>
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<varlistentry>
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<term><option>ACTION</option></term>
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<listitem>
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<para><replaceable>add</replaceable> or <replaceable>remove</replaceable> signifies
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the addition or the removal of a device.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>DEVPATH</option></term>
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<listitem>
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<para>The sysfs devpath without the mountpoint but a leading slash.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>SUBSYSTEM</option></term>
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<listitem>
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<para>The kernel subsystem the device belongs to.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>UDEV_LOG</option></term>
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<listitem>
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<para>Overrides the syslog priority specified in the config file.</para>
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</listitem>
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|
</varlistentry>
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|
</variablelist>
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|
</refsect1>
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|
|
|
<refsect1><title>AUTHOR</title>
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<para>Written by Greg Kroah-Hartman <email>greg@kroah.com</email> and
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Kay Sievers <email>kay.sievers@vrfy.org</email>. With much help from
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Dan Stekloff <email>dsteklof@us.ibm.com</email> and many others.</para>
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|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>SEE ALSO</title>
|
|
<para><citerefentry>
|
|
<refentrytitle>udev</refentrytitle><manvolnum>8</manvolnum>
|
|
</citerefentry>,
|
|
<citerefentry>
|
|
<refentrytitle>udevinfo</refentrytitle><manvolnum>8</manvolnum>
|
|
</citerefentry>,
|
|
<citerefentry>
|
|
<refentrytitle>udevd</refentrytitle><manvolnum>8</manvolnum>
|
|
</citerefentry>,
|
|
<citerefentry>
|
|
<refentrytitle>udevmonitor</refentrytitle><manvolnum>8</manvolnum>
|
|
</citerefentry></para>
|
|
</refsect1>
|
|
</refentry>
|
|
</section>
|
|
</article>
|