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Merge branch 'docs/udev.xml' of git://github.com/mfwitten/udev
This commit is contained in:
Kay Sievers
commit
cbfad6af1f
169
udev/udev.xml
169
udev/udev.xml
@ -27,23 +27,23 @@
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names provide a way to reliably identify devices based on their properties or
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current configuration.</para>
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<para>The udev daemon <citerefentry><refentrytitle>udevd</refentrytitle>
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<manvolnum>8</manvolnum></citerefentry> receives device uevents directly from
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<para>The udev daemon, <citerefentry><refentrytitle>udevd</refentrytitle>
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<manvolnum>8</manvolnum></citerefentry>, receives device uevents directly from
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the kernel whenever a device is added or removed from the system, or it changes its
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state. When udev receives a device event, it matches its configured set of rules
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against various device attributes to identify the device. Rules that match, may
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provide additional device information to be stored in the udev database, or information
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against various device attributes to identify the device. Rules that match may
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provide additional device information to be stored in the udev database or
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to be used to create meaningful symlink names.</para>
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<para>All device information udev processes, is stored in the udev database and
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<para>All device information udev processes is stored in the udev database and
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sent out to possible event subscribers. Access to all stored data and the event
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sources are provided by the library libudev.</para>
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sources is provided by the library libudev.</para>
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</refsect1>
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<refsect1><title>Configuration</title>
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<para>udev configuration files are placed in <filename>/etc/udev/</filename>
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and <filename>/lib/udev/</filename>. All empty lines, or lines beginning with
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'#' will be ignored.</para>
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and <filename>/lib/udev/</filename>. All empty lines or lines beginning with
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'#' are 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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@ -74,26 +74,26 @@
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default rules directory <filename>/lib/udev/rules.d/</filename>,
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the custom rules directory <filename>/etc/udev/rules.d/</filename>
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and the temporary rules directory <filename>/run/udev/rules.d/</filename>.
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All rule files are sorted and processed in lexical order, regardless
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in which of these directories they live. Files in
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<filename>/etc/udev/rules.d/</filename> have precedence over files with
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the same name in <filename>/lib/udev/rules.d/</filename>. This can be
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All rule files are collectively sorted and processed in lexical order,
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regardless of the directories in which they live. However, files in
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<filename>/etc/udev/rules.d/</filename> take precedence over files with
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the same name in <filename>/lib/udev/rules.d/</filename>; this can be
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used to ignore a default rules file if needed.</para>
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<para>Rule files must end in <filename>.rules</filename>, other extensions
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are ignored.</para>
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<para>Rule files must have the extension <filename>.rules</filename>; other
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extensions are ignored.</para>
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<para>Every line in the rules file contains at least one key value pair.
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There are two kind of keys, match and assignment keys.
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<para>Every line in the rules file contains at least one key-value pair.
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There are two kind of keys: match and assignment.
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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.</para>
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assignment keys get the specified value assigned.</para>
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<para>A matching rule may rename a network interface, add symlinks
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pointing to the device node, or run a specified program as part of
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the event handling.</para>
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<para>A rule 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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<para>A rule consists of a comma-separated list of one or more key-value pairs.
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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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@ -113,7 +113,7 @@
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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. Keys that represent a list, are reset
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<para>Assign 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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@ -128,8 +128,7 @@
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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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<para>Assign a value to a key finally; disallow any later changes.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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@ -189,7 +188,7 @@
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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 driver name of the event device. Only set for devices
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<para>Match the driver name of the event device. Only set this key for devices
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which are bound to a driver at the time the event is generated.</para>
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</listitem>
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</varlistentry>
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@ -197,8 +196,8 @@
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<term><option>ATTR{<replaceable>filename</replaceable>}</option></term>
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<listitem>
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<para>Match sysfs attribute values of the event device. Trailing
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whitespace in the attribute values is ignored, if the specified match
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value does not contain trailing whitespace itself.
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whitespace in the attribute values is ignored unless the specified match
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value itself contains trailing whitespace.
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</para>
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</listitem>
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</varlistentry>
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@ -229,8 +228,8 @@
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<listitem>
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<para>Search the devpath upwards for a device with matching sysfs attribute values.
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If multiple <option>ATTRS</option> matches are specified, all of them
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must match on the same device. Trailing whitespace in the attribute values is ignored,
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if the specified match value does not contain trailing whitespace itself.</para>
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must match on the same device. Trailing whitespace in the attribute values is ignored
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unless the specified match value itself contains trailing whitespace.</para>
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</listitem>
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</varlistentry>
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@ -259,10 +258,11 @@
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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 a program. The key is true, if the program returns
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<para>Execute a program to determine whether there
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is a match; the key is true if the program returns
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successfully. The device properties are made available to the
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executed program in the environment. The program's output printed to
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stdout, is available in the RESULT key.</para>
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executed program in the environment. The program's stdout
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is available in the RESULT key.</para>
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</listitem>
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</varlistentry>
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@ -275,13 +275,13 @@
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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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<para>Most of the fields support 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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<para>Matches zero or more characters.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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@ -295,8 +295,8 @@
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<listitem>
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<para>Matches any single character specified within the brackets. For
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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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Ranges are also supported via the '-' character.
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For example, to match on the range of all digits, the pattern [0-9] could
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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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@ -308,33 +308,33 @@
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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, a network interface should be renamed to. Or as
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a temporary workaround, the name a device node should be named.
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Usually the kernel provides the defined node name, or even creates
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<para>What a network interface should be named.</para>
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<para>Also, as a temporary workaround, this is what a device node
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should be named; usually the kernel provides the defined node name or creates
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and removes the node before udev even receives any event. Changing
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the node name from the kernel's default creates inconsistencies
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and is not supported. If the kernel and NAME specify different names,
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an error will be logged. Udev is only expected to handle device node
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an error is logged. udev is only expected to handle device node
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permissions and to create additional symlinks, not to change
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kernel-provided device node names. Instead of renaming a device node,
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SYMLINK should be used. Symlink names must never conflict with
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device node names, it will result in unpredictable behavior.</para>
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SYMLINK should be used. However, symlink names must never conflict with
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device node names, as that would result in unpredictable behavior.</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 will add
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<para>The name of a symlink targeting the node. Every matching rule adds
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this value to the list of symlinks to be created. Multiple symlinks may be
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specified by separating the names by the space character. In case multiple
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devices claim the same name, the link will always point to the device with
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the highest link_priority. If the current device goes away, the links will
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be re-evaluated and the device with the next highest link_priority will own
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the link. If no link_priority is specified, the order of the devices, and
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which one of them will own the link, is undefined. Claiming the same name for
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a symlink, which is or might be used for a device node, may result in
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unexpected behavior and is not supported.
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devices claim the same name, the link always points to the device with
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the highest link_priority. If the current device goes away, the links are
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re-evaluated and the device with the next highest link_priority becomes the owner of
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the link. If no link_priority is specified, the order of the devices (and
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which one of them owns the link) is undefined. Also, symlink names must
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never conflict with the kernel's default device node names, as that would
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result in unpredictable behavior.
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</para>
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</listitem>
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</varlistentry>
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@ -359,7 +359,8 @@
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<term><option>ENV{<replaceable>key</replaceable>}</option></term>
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<listitem>
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<para>Set a device property value. Property names with a leading '.'
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are not stored in the database or exported to external tool or events.</para>
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are neither stored in the database nor exported to events or
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external tools (run by, say, the PROGRAM match key).</para>
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</listitem>
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</varlistentry>
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@ -385,23 +386,25 @@
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this or a dependent device. Long running tasks need to be immediately
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detached from the event process itself.</para>
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<para>If no absolute path is given, the program is expected to live in
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<filename>/lib/udev</filename>, otherwise the absolute path must be
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specified. Program name and arguments are separated by spaces. Single quotes
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can be used to specify arguments with spaces.</para>
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the directory provided at compile-time to configure via --libexecdir
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(this is usually <filename>/lib/udev</filename>), otherwise the absolute
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path must be specified. The program name and following arguments are
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separated by spaces. Single quotes can be used to specify arguments with
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spaces.</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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<para>A named label to which a GOTO may jump.</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 name</para>
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<para>Jumps to the next LABEL with a matching name.</para>
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</listitem>
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</varlistentry>
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@ -423,8 +426,8 @@
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<varlistentry>
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<term><option>file</option></term>
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<listitem>
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<para>Import a text file specified as the assigned value, which must be in
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environment key format.</para>
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<para>Import a text file specified as the assigned value, the content
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of which must be in environment key format.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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@ -438,8 +441,8 @@
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<varlistentry>
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<term><option>cmdline</option></term>
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<listitem>
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<para>Import a single property from the kernel commandline. For simple flags
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the value of the property will be set to '1'.</para>
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<para>Import a single property from the kernel command line. For simple flags
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the value of the property is set to '1'.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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@ -453,7 +456,7 @@
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</listitem>
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</varlistentry>
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</variablelist>
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<para>If no option is given, udev will choose between <option>program</option>
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<para>If no option is given, udev chooses between <option>program</option>
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and <option>file</option> based on the executable bit of the file
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permissions.</para>
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</listitem>
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@ -462,9 +465,9 @@
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<varlistentry>
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<term><option>WAIT_FOR</option></term>
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<listitem>
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<para>Wait for a file to become available or until a 10
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seconds timeout expires. The path is relative to the sysfs device,
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i. e. if no path is specified this waits for an attribute to appear.</para>
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<para>Wait for a file to become available or until a timeout of
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10 seconds expires. The path is relative to the sysfs device;
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if no path is specified, this waits for an attribute to appear.</para>
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</listitem>
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</varlistentry>
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@ -483,8 +486,8 @@
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<varlistentry>
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<term><option>event_timeout=</option></term>
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<listitem>
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<para>Number of seconds an event will wait for operations to finish, before it
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will terminate itself.</para>
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<para>Number of seconds an event waits for operations to finish before
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giving up and terminating itself.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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@ -498,18 +501,18 @@
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<varlistentry>
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<term><option>static_node=</option></term>
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<listitem>
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<para>Apply the permissions specified in this rule to a static device node with
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the specified name. Static device nodes might be provided by kernel modules,
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<para>Apply the permissions specified in this rule to the static device node with
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the specified name. Static device nodes might be provided by kernel modules
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or copied from <filename>/lib/udev/devices</filename>. These nodes might not have
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a corresponding kernel device at the time udevd is started, and allow to trigger
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automatic kernel module on-demand loading.</para>
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a corresponding kernel device at the time udevd is started; they can trigger
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automatic kernel module loading.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>watch</option></term>
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<listitem>
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<para>Watch the device node with inotify, when closed after being opened for
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writing, a change uevent will be synthesised.</para>
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<para>Watch the device node with inotify; when the node is closed after being opened for
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writing, a change uevent is synthesized.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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@ -525,10 +528,10 @@
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<para>The <option>NAME</option>, <option>SYMLINK</option>, <option>PROGRAM</option>,
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<option>OWNER</option>, <option>GROUP</option>, <option>MODE</option> and <option>RUN</option>
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fields support simple printf-like string substitutions. The <option>RUN</option>
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format chars gets applied after all rules have been processed, right before the program
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is executed. It allows the use of device properties set by earlier matching
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rules. For all other fields, substitutions are applied while the individual rule is
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fields support simple string substitutions. The <option>RUN</option>
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substitutions are performed after all rules have been processed, right before the program
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is executed, allowing for the use of device properties set by earlier matching
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rules. For all other fields, substitutions are performed while the individual rule is
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||||
being processed. The available substitutions are:</para>
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||||
<variablelist>
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<varlistentry>
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@ -574,12 +577,12 @@
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<varlistentry>
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||||
<term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term>
|
||||
<listitem>
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||||
<para>The value of a sysfs attribute found at the device, where
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<para>The value of a sysfs attribute found at the device where
|
||||
all keys of the rule have matched. If the matching device does not have
|
||||
such an attribute, and a previous KERNELS, SUBSYSTEMS, DRIVERS, or
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||||
ATTRS test selected a parent device, use the attribute from that
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parent device.
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||||
If the attribute is a symlink, the last element of the symlink target is
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||||
ATTRS test selected a parent device, then the attribute from that
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||||
parent device is used.</para>
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||||
<para>If the attribute is a symlink, the last element of the symlink target is
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||||
returned as the value.</para>
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||||
</listitem>
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||||
</varlistentry>
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||||
@ -609,9 +612,9 @@
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<term><option>$result</option>, <option>%c</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
|
||||
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>.
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||||
If the number is followed by the '+' char this part plus all remaining parts
|
||||
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>
|
||||
</listitem>
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||||
</varlistentry>
|
||||
@ -634,8 +637,8 @@
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||||
<varlistentry>
|
||||
<term><option>$links</option></term>
|
||||
<listitem>
|
||||
<para>The current list of symlinks, separated by a space character. The value is
|
||||
only set if an earlier rule assigned a value, or during a remove events.</para>
|
||||
<para>A space-separated list of the current symlinks. The value is
|
||||
only set during a remove event or if an earlier rule assigned a value.</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
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||||
@ -656,7 +659,7 @@
|
||||
<varlistentry>
|
||||
<term><option>$tempnode</option>, <option>%N</option></term>
|
||||
<listitem>
|
||||
<para>The name of a created temporary device node to provide access to
|
||||
<para>The name of a temporary device node created to provide access to
|
||||
the device from a external program before the real node is created.</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
||||
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