diff options
author | Yu Watanabe <watanabe.yu+github@gmail.com> | 2020-10-30 09:52:45 +0900 |
---|---|---|
committer | GitHub <noreply@github.com> | 2020-10-30 09:52:45 +0900 |
commit | 819a555bc5cccd6b4e8b53b7b5036744a94142a7 (patch) | |
tree | fb7b7a18837a18934c2425be6be0680a4acbc2dc /man | |
parent | 58f848148f0bbdbedd0243de289944804b772094 (diff) | |
parent | bc117ec35957f698db4d92bc670605e04f85ccf4 (diff) | |
download | systemd-819a555bc5cccd6b4e8b53b7b5036744a94142a7.tar.gz |
Merge pull request #17399 from afq984/udev-escaped-string
Allow escaped string in udev rules
Diffstat (limited to 'man')
-rw-r--r-- | man/udev.xml | 1468 |
1 files changed, 746 insertions, 722 deletions
diff --git a/man/udev.xml b/man/udev.xml index a41a39a43f..4f230c206c 100644 --- a/man/udev.xml +++ b/man/udev.xml @@ -23,7 +23,8 @@ <refpurpose>Dynamic device management</refpurpose> </refnamediv> - <refsect1><title>Description</title> + <refsect1> + <title>Description</title> <para>udev supplies the system software with device events, manages permissions of device nodes and may create additional symlinks in the <filename>/dev/</filename> directory, or renames network interfaces. The kernel usually just assigns unpredictable @@ -44,7 +45,8 @@ sources is provided by the library libudev.</para> </refsect1> - <refsect1><title>Rules Files</title> + <refsect1> + <title>Rules Files</title> <para>The udev rules are read from the files located in the system rules directories <filename>/usr/lib/udev/rules.d</filename> and <filename>/usr/local/lib/udev/rules.d</filename>, the volatile runtime directory <filename>/run/udev/rules.d</filename> and the local administration @@ -68,727 +70,749 @@ pointing to the device node, or run a specified program as part of the event handling.</para> - <para>A rule consists of a comma-separated list of one or more key-value pairs. - Each key has a distinct operation, depending on the used operator. Valid - operators are:</para> - <variablelist> - <varlistentry> - <term><literal>==</literal></term> - <listitem> - <para>Compare for equality.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><literal>!=</literal></term> - <listitem> - <para>Compare for inequality.</para> - </listitem> - </varlistentry> - - <varlistentry> - <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> - </listitem> - </varlistentry> - - <varlistentry> - <term><literal>+=</literal></term> - <listitem> - <para>Add the value to a key that holds a list of entries.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><literal>-=</literal></term> - <listitem> - <para>Remove the value from a key that holds a list of entries.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><literal>:=</literal></term> - <listitem> - <para>Assign a value to a key finally; disallow any later changes.</para> - </listitem> - </varlistentry> - </variablelist> - - <para>The following key names can be used to match against device properties. - Some of the keys also match against properties of the parent devices in sysfs, - not only the device that has generated the event. If multiple keys that match - a parent device are specified in a single rule, all these keys must match at - one and the same parent device.</para> - <variablelist class='udev-directives'> - <varlistentry> - <term><varname>ACTION</varname></term> - <listitem> - <para>Match the name of the event action.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>DEVPATH</varname></term> - <listitem> - <para>Match the devpath of the event device.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>KERNEL</varname></term> - <listitem> - <para>Match the name of the event device.</para> - </listitem> - </varlistentry> - - <varlistentry> - <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> - </listitem> - </varlistentry> - - <varlistentry> - <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 - rules. There may be multiple symlinks; only one needs to match. - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>SUBSYSTEM</varname></term> - <listitem> - <para>Match the subsystem of the event device.</para> - </listitem> - </varlistentry> - <varlistentry> - <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><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 - value itself contains trailing whitespace. - </para> - </listitem> - </varlistentry> - <varlistentry> - <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term> - <listitem> - <para>Match a kernel parameter value. - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>KERNELS</varname></term> - <listitem> - <para>Search the devpath upwards for a matching device name.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>SUBSYSTEMS</varname></term> - <listitem> - <para>Search the devpath upwards for a matching device subsystem name.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>DRIVERS</varname></term> - <listitem> - <para>Search the devpath upwards for a matching device driver name.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>ATTRS{<replaceable>filename</replaceable>}</varname></term> - <listitem> - <para>Search the devpath upwards for a device with matching sysfs attribute values. - 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><varname>TAGS</varname></term> - <listitem> - <para>Search the devpath upwards for a device with matching tag.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> - <listitem> - <para>Match against a device property value.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>CONST{<replaceable>key</replaceable>}</varname></term> - <listitem> - <para>Match against a system-wide constant. Supported keys are:</para> - <variablelist> - <varlistentry> - <term><literal>arch</literal></term> - <listitem> - <para>System's architecture. See <option>ConditionArchitecture=</option> in - <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> - for possible values.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><literal>virt</literal></term> - <listitem> - <para>System's virtualization environment. See - <citerefentry><refentrytitle>systemd-detect-virt</refentrytitle><manvolnum>1</manvolnum></citerefentry> - for possible values.</para> - </listitem> - </varlistentry> - </variablelist> - <para>Unknown keys will never match.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>TAG</varname></term> - <listitem> - <para>Match against a device tag.</para> - </listitem> - </varlistentry> - - <varlistentry> - <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> - </listitem> - </varlistentry> - - <varlistentry> - <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 standard output 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> - - <para>Note that multiple <varname>PROGRAM</varname> keys may be specified in one rule, and - <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as - <literal>==</literal>.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>RESULT</varname></term> - <listitem> - <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 glob pattern matching and - alternate patterns. The following special characters are supported:</para> - <variablelist> - <varlistentry> - <term><literal>*</literal></term> - <listitem> - <para>Matches zero or more characters.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><literal>?</literal></term> - <listitem> - <para>Matches any single character.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><literal>[]</literal></term> - <listitem> - <para>Matches any single character specified within the brackets. For - 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> - <varlistentry> - <term><literal>|</literal></term> - <listitem> - <para>Separates alternative patterns. For example, the pattern string - <literal>abc|x*</literal> would match either <literal>abc</literal> - or <literal>x*</literal>.</para> - </listitem> - </varlistentry> - </variablelist> - - <para>The following keys can get values assigned:</para> - <variablelist class='udev-directives'> - <varlistentry> - <term><varname>NAME</varname></term> - <listitem> - <para>The name to use for a network interface. See - <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry> - for a higher-level mechanism for setting the interface name. - The name of a device node cannot be changed by udev, only additional - symlinks can be created.</para> - </listitem> - </varlistentry> - - <varlistentry> - <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.</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><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> - </listitem> - </varlistentry> - - <varlistentry> - <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> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term> - <listitem> - <para>The value that should be written to kernel parameter.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> - <listitem> - <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, for example, the <varname>PROGRAM</varname> - match key).</para> - </listitem> - </varlistentry> - - <varlistentry> - <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 - devices. The implementation can only work efficiently if only a few - tags are attached to a device. It is only meant to be used in - contexts with specific device filter requirements, and not as a - general-purpose flag. Excessive use might result in inefficient event - handling.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>RUN{<replaceable>type</replaceable>}</varname></term> - <listitem> - <para>Specify a program to be executed after processing of all the rules for the event. With - <literal>+=</literal>, this invocation is added to the list, and with <literal>=</literal> or - <literal>:=</literal>, it replaces any previous contents of the list. Please note that both - <literal>program</literal> and <literal>builtin</literal> types described below use a single - list, so clearing the list with <literal>:=</literal> and <literal>=</literal> affects both - types.</para> - - <para><replaceable>type</replaceable> may be:</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>Note that running programs that access the network or mount/unmount filesystems is not - allowed inside of udev rules, due to the default sandbox that is enforced on - <filename>systemd-udevd.service</filename>.</para> - - <para>Starting daemons or other long-running processes is not allowed; the forked processes, - detached or not, will be unconditionally killed after the event handling has finished. In order - to activate long-running processes from udev rules, provide a service unit and pull it in from a - udev device using the <varname>SYSTEMD_WANTS</varname> device property. See - <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry> - for details.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>LABEL</varname></term> - <listitem> - <para>A named label to which a <varname>GOTO</varname> may jump.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>GOTO</varname></term> - <listitem> - <para>Jumps to the next <varname>LABEL</varname> with a matching name.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term> - <listitem> - <para>Import a set of variables as device properties, depending on - <replaceable>type</replaceable>:</para> - - <variablelist> - <varlistentry> - <term><literal>program</literal></term> - <listitem> - <para>Execute an external program specified as the assigned - value and, if it returns successfully, - import its output, which must be in environment key - format. Path specification, command/argument separation, - and quoting work like in <varname>RUN</varname>.</para> - </listitem> - </varlistentry> - <varlistentry> - <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><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 - by an earlier event.</para> - </listitem> - </varlistentry> - <varlistentry> - <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 <literal>1</literal>.</para> - </listitem> - </varlistentry> - <varlistentry> - <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 glob pattern matching used for - comparisons).</para> - </listitem> - </varlistentry> - </variablelist> - - <para>This can only be used for very short-running foreground tasks. For details see - <option>RUN</option>.</para> - - <para>Note that multiple <varname>IMPORT{}</varname> keys may be specified in one rule, and - <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as - <literal>==</literal>. The key is true if the import is successful, unless <literal>!=</literal> - is used as the operator which causes the key to be true if the import failed.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><varname>OPTIONS</varname></term> - <listitem> - <para>Rule and device options:</para> - <variablelist class='udev-directives'> - <varlistentry> - <term><option>link_priority=<replaceable>value</replaceable></option></term> - <listitem> - <para>Specify the priority of the created symlinks. Devices with higher - priorities overwrite existing symlinks of other devices. The default is 0.</para> - </listitem> - </varlistentry> - <varlistentry> - <term><option>string_escape=<replaceable>none|replace</replaceable></option></term> - <listitem> - <para>Usually, control and other possibly unsafe characters are replaced - in strings used for device naming. The mode of replacement can be specified - with this option.</para> - </listitem> - </varlistentry> - <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. 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> - </listitem> - </varlistentry> - <varlistentry> - <term><option>nowatch</option></term> - <listitem> - <para>Disable the watching of a device node with inotify.</para> - </listitem> - </varlistentry> + <para>A rule consists of a comma-separated list of one or more key-operator-value expressions. + Each expression has a distinct effect, depending on the key and operator used.</para> + + <refsect2> + <title>Operators</title> + <variablelist> + <varlistentry> + <term><literal>==</literal></term> + <listitem> + <para>Compare for equality.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>!=</literal></term> + <listitem> + <para>Compare for inequality.</para> + </listitem> + </varlistentry> + + <varlistentry> + <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> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>+=</literal></term> + <listitem> + <para>Add the value to a key that holds a list of entries.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>-=</literal></term> + <listitem> + <para>Remove the value from a key that holds a list of entries.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>:=</literal></term> + <listitem> + <para>Assign a value to a key finally; disallow any later changes.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect2> + + <refsect2> + <title>Values</title> + <para>Values are written as double quoted strings, such as ("string"). + To include a quotation mark (") in the value, precede it by a backslash (\"). + Any other occurrences of a character followed by a backslash are not further unescaped. + That is, "\t\n" is treated as four characters: + backslash, lowercase t, backslash, lowercase n.</para> + + <para>The string can be prefixed with a lowercase e (e"string\n") to mark the string as + <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style escaped</ulink>. + For example, e"string\n" is parsed as 7 characters: 6 lowercase letters and a newline. + This can be useful for writting special characters when a kernel driver requires them.</para> + + <para>Please note that <constant>NUL</constant> is not allowed in either string variant.</para> + </refsect2> + + <refsect2> + <title>Keys</title> + <para>The following key names can be used to match against device properties. + Some of the keys also match against properties of the parent devices in sysfs, + not only the device that has generated the event. If multiple keys that match + a parent device are specified in a single rule, all these keys must match at + one and the same parent device.</para> + <variablelist class='udev-directives'> + <varlistentry> + <term><varname>ACTION</varname></term> + <listitem> + <para>Match the name of the event action.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>DEVPATH</varname></term> + <listitem> + <para>Match the devpath of the event device.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>KERNEL</varname></term> + <listitem> + <para>Match the name of the event device.</para> + </listitem> + </varlistentry> + + <varlistentry> + <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> + </listitem> + </varlistentry> + + <varlistentry> + <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 + rules. There may be multiple symlinks; only one needs to match. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>SUBSYSTEM</varname></term> + <listitem> + <para>Match the subsystem of the event device.</para> + </listitem> + </varlistentry> + <varlistentry> + <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><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 + value itself contains trailing whitespace. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term> + <listitem> + <para>Match a kernel parameter value. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>KERNELS</varname></term> + <listitem> + <para>Search the devpath upwards for a matching device name.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>SUBSYSTEMS</varname></term> + <listitem> + <para>Search the devpath upwards for a matching device subsystem name.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>DRIVERS</varname></term> + <listitem> + <para>Search the devpath upwards for a matching device driver name.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>ATTRS{<replaceable>filename</replaceable>}</varname></term> + <listitem> + <para>Search the devpath upwards for a device with matching sysfs attribute values. + 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><varname>TAGS</varname></term> + <listitem> + <para>Search the devpath upwards for a device with matching tag.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> + <listitem> + <para>Match against a device property value.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>CONST{<replaceable>key</replaceable>}</varname></term> + <listitem> + <para>Match against a system-wide constant. Supported keys are:</para> + <variablelist> + <varlistentry> + <term><literal>arch</literal></term> + <listitem> + <para>System's architecture. See <option>ConditionArchitecture=</option> in + <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> + for possible values.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>virt</literal></term> + <listitem> + <para>System's virtualization environment. See + <citerefentry><refentrytitle>systemd-detect-virt</refentrytitle><manvolnum>1</manvolnum></citerefentry> + for possible values.</para> + </listitem> + </varlistentry> + </variablelist> + <para>Unknown keys will never match.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>TAG</varname></term> + <listitem> + <para>Match against a device tag.</para> + </listitem> + </varlistentry> + + <varlistentry> + <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> + </listitem> + </varlistentry> + + <varlistentry> + <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 standard output 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> + + <para>Note that multiple <varname>PROGRAM</varname> keys may be specified in one rule, and + <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as + <literal>==</literal>.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>RESULT</varname></term> + <listitem> + <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 glob pattern matching and + alternate patterns. The following special characters are supported:</para> + <variablelist> + <varlistentry> + <term><literal>*</literal></term> + <listitem> + <para>Matches zero or more characters.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>?</literal></term> + <listitem> + <para>Matches any single character.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><literal>[]</literal></term> + <listitem> + <para>Matches any single character specified within the brackets. For + 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> + <varlistentry> + <term><literal>|</literal></term> + <listitem> + <para>Separates alternative patterns. For example, the pattern string + <literal>abc|x*</literal> would match either <literal>abc</literal> + or <literal>x*</literal>.</para> + </listitem> + </varlistentry> + </variablelist> + + <para>The following keys can get values assigned:</para> + <variablelist class='udev-directives'> + <varlistentry> + <term><varname>NAME</varname></term> + <listitem> + <para>The name to use for a network interface. See + <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry> + for a higher-level mechanism for setting the interface name. + The name of a device node cannot be changed by udev, only additional + symlinks can be created.</para> + </listitem> + </varlistentry> + + <varlistentry> + <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.</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><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> + </listitem> + </varlistentry> + + <varlistentry> + <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> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term> + <listitem> + <para>The value that should be written to kernel parameter.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> + <listitem> + <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, for example, the <varname>PROGRAM</varname> + match key).</para> + </listitem> + </varlistentry> + + <varlistentry> + <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 + devices. The implementation can only work efficiently if only a few + tags are attached to a device. It is only meant to be used in + contexts with specific device filter requirements, and not as a + general-purpose flag. Excessive use might result in inefficient event + handling.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>RUN{<replaceable>type</replaceable>}</varname></term> + <listitem> + <para>Specify a program to be executed after processing of all the rules for the event. With + <literal>+=</literal>, this invocation is added to the list, and with <literal>=</literal> or + <literal>:=</literal>, it replaces any previous contents of the list. Please note that both + <literal>program</literal> and <literal>builtin</literal> types described below use a single + list, so clearing the list with <literal>:=</literal> and <literal>=</literal> affects both + types.</para> + + <para><replaceable>type</replaceable> may be:</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>Note that running programs that access the network or mount/unmount filesystems is not + allowed inside of udev rules, due to the default sandbox that is enforced on + <filename>systemd-udevd.service</filename>.</para> + + <para>Starting daemons or other long-running processes is not allowed; the forked processes, + detached or not, will be unconditionally killed after the event handling has finished. In order + to activate long-running processes from udev rules, provide a service unit and pull it in from a + udev device using the <varname>SYSTEMD_WANTS</varname> device property. See + <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry> + for details.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>LABEL</varname></term> + <listitem> + <para>A named label to which a <varname>GOTO</varname> may jump.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>GOTO</varname></term> + <listitem> + <para>Jumps to the next <varname>LABEL</varname> with a matching name.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term> + <listitem> + <para>Import a set of variables as device properties, depending on + <replaceable>type</replaceable>:</para> + + <variablelist> + <varlistentry> + <term><literal>program</literal></term> + <listitem> + <para>Execute an external program specified as the assigned + value and, if it returns successfully, + import its output, which must be in environment key + format. Path specification, command/argument separation, + and quoting work like in <varname>RUN</varname>.</para> + </listitem> + </varlistentry> + <varlistentry> + <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><option>db_persist</option></term> - <listitem> - <para>Set the flag (sticky bit) on the udev database entry - of the event device. Device properties are then kept in the - database even when - <command>udevadm info --cleanup-db</command> is called. - This option can be useful in certain cases - (e.g. Device Mapper devices) for persisting device state - on the transition from initramfs.</para> - </listitem> - </varlistentry> - </variablelist> - </listitem> - </varlistentry> - </variablelist> - - <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>, - <varname>PROGRAM</varname>, <varname>OWNER</varname>, - <varname>GROUP</varname>, <varname>MODE</varname>, <varname>SECLABEL</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>$kernel</option>, <option>%k</option></term> - <listitem> - <para>The kernel name for this device.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$number</option>, <option>%n</option></term> - <listitem> - <para>The kernel number for this device. For example, <literal>sda3</literal> has kernel number - 3.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$devpath</option>, <option>%p</option></term> - <listitem> - <para>The devpath of the device.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$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> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$driver</option></term> - <listitem> - <para>The driver name of the device matched while searching the - devpath upwards for <option>SUBSYSTEMS</option>, - <option>KERNELS</option>, <option>DRIVERS</option>, and - <option>ATTRS</option>. - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$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 <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>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term> - <listitem> - <para>A device property value.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$major</option>, <option>%M</option></term> - <listitem> - <para>The kernel major number for the device.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$minor</option>, <option>%m</option></term> - <listitem> - <para>The kernel minor number for the device.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$result</option>, <option>%c</option></term> - <listitem> - <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: <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>$parent</option>, <option>%P</option></term> - <listitem> - <para>The node name of the parent device.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$name</option></term> - <listitem> - <para>The current name of the device. If not changed by a rule, it is the - name of the kernel device.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$links</option></term> - <listitem> - <para>A space-separated list of the current symlinks. The value is - only set during a remove event or if an earlier rule assigned a value.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$root</option>, <option>%r</option></term> - <listitem> - <para>The udev_root value.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$sys</option>, <option>%S</option></term> - <listitem> - <para>The sysfs mount point.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$devnode</option>, <option>%N</option></term> - <listitem> - <para>The name of the device node.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>%%</option></term> - <listitem> - <para>The <literal>%</literal> character itself.</para> - </listitem> - </varlistentry> - - <varlistentry> - <term><option>$$</option></term> - <listitem> - <para>The <literal>$</literal> character itself.</para> - </listitem> - </varlistentry> - </variablelist> + <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><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 + by an earlier event.</para> + </listitem> + </varlistentry> + <varlistentry> + <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 <literal>1</literal>.</para> + </listitem> + </varlistentry> + <varlistentry> + <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 glob pattern matching used for + comparisons).</para> + </listitem> + </varlistentry> + </variablelist> + + <para>This can only be used for very short-running foreground tasks. For details see + <option>RUN</option>.</para> + + <para>Note that multiple <varname>IMPORT{}</varname> keys may be specified in one rule, and + <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as + <literal>==</literal>. The key is true if the import is successful, unless <literal>!=</literal> + is used as the operator which causes the key to be true if the import failed.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>OPTIONS</varname></term> + <listitem> + <para>Rule and device options:</para> + <variablelist class='udev-directives'> + <varlistentry> + <term><option>link_priority=<replaceable>value</replaceable></option></term> + <listitem> + <para>Specify the priority of the created symlinks. Devices with higher + priorities overwrite existing symlinks of other devices. The default is 0.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><option>string_escape=<replaceable>none|replace</replaceable></option></term> + <listitem> + <para>Usually, control and other possibly unsafe characters are replaced + in strings used for device naming. The mode of replacement can be specified + with this option.</para> + </listitem> + </varlistentry> + <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. 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> + </listitem> + </varlistentry> + <varlistentry> + <term><option>nowatch</option></term> + <listitem> + <para>Disable the watching of a device node with inotify.</para> + </listitem> + </varlistentry> + <varlistentry> + <term><option>db_persist</option></term> + <listitem> + <para>Set the flag (sticky bit) on the udev database entry + of the event device. Device properties are then kept in the + database even when + <command>udevadm info --cleanup-db</command> is called. + This option can be useful in certain cases + (e.g. Device Mapper devices) for persisting device state + on the transition from initramfs.</para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + </variablelist> + + <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>, + <varname>PROGRAM</varname>, <varname>OWNER</varname>, + <varname>GROUP</varname>, <varname>MODE</varname>, <varname>SECLABEL</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> + <para>The kernel name for this device.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$number</option>, <option>%n</option></term> + <listitem> + <para>The kernel number for this device. For example, <literal>sda3</literal> has kernel number + 3.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$devpath</option>, <option>%p</option></term> + <listitem> + <para>The devpath of the device.</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> + </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> + </listitem> + </varlistentry> + + <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 <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>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term> + <listitem> + <para>A device property value.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$major</option>, <option>%M</option></term> + <listitem> + <para>The kernel major number for the device.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$minor</option>, <option>%m</option></term> + <listitem> + <para>The kernel minor number for the device.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$result</option>, <option>%c</option></term> + <listitem> + <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: <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>$parent</option>, <option>%P</option></term> + <listitem> + <para>The node name of the parent device.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$name</option></term> + <listitem> + <para>The current name of the device. If not changed by a rule, it is the + name of the kernel device.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$links</option></term> + <listitem> + <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> + + <varlistentry> + <term><option>$root</option>, <option>%r</option></term> + <listitem> + <para>The udev_root value.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$sys</option>, <option>%S</option></term> + <listitem> + <para>The sysfs mount point.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$devnode</option>, <option>%N</option></term> + <listitem> + <para>The name of the device node.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>%%</option></term> + <listitem> + <para>The <literal>%</literal> character itself.</para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>$$</option></term> + <listitem> + <para>The <literal>$</literal> character itself.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect2> </refsect1> <refsect1> |