</listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>TAGS</option></term>
+ <listitem>
+ <para>Search the devpath upwards for a device with matching tag.</para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>ENV{<replaceable>key</replaceable>}</option></term>
<listitem>
</varlistentry>
</variablelist>
- <para>Most of the fields support a shell style pattern matching. The following
+ <para>Most of the fields support shell-style pattern matching. The following
pattern characters are supported:</para>
<variablelist>
<varlistentry>
<term><option>*</option></term>
<listitem>
- <para>Matches zero, or any number of characters.</para>
+ <para>Matches zero or more characters.</para>
</listitem>
</varlistentry>
<varlistentry>
<listitem>
<para>Matches any single character specified within the brackets. For
example, the pattern string 'tty[SR]' would match either 'ttyS' or 'ttyR'.
- Ranges are also supported within this match with the '-' character.
- For example, to match on the range of all digits, the pattern [0-9] would
+ Ranges are also supported via the '-' character.
+ For example, to match on the range of all digits, the pattern [0-9] could
be used. If the first character following the '[' is a '!', any characters
not enclosed are matched.</para>
</listitem>
<varlistentry>
<term><option>NAME</option></term>
<listitem>
- <para>The name, a network interface should be renamed to. Or as
- a temporary workaround, the name a device node should be named.
- Usually the kernel provides the defined node name, or even creates
+ <para>What a network interface should be named.</para>
+ <para>Also, as a temporary workaround, this is what a device node
+ should be named; usually the kernel provides the defined node name or creates
and removes the node before udev even receives any event. Changing
the node name from the kernel's default creates inconsistencies
and is not supported. If the kernel and NAME specify different names,
- an error is logged. Udev is only expected to handle device node
+ an error is logged. udev is only expected to handle device node
permissions and to create additional symlinks, not to change
kernel-provided device node names. Instead of renaming a device node,
- SYMLINK should be used. Symlink names must never conflict with
- device node names, it results in unpredictable behavior.</para>
+ SYMLINK should be used. However, symlink names must never conflict with
+ device node names, as that would result in unpredictable behavior.</para>
</listitem>
</varlistentry>
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. Claiming the same name for
- a symlink, which is or might be used for a device node, may result in
- unexpected behavior and is not supported.
+ the link. If no link_priority is specified, the order of the devices (and
+ which one of them owns the link) is undefined. Also, symlink names must
+ never conflict with the kernel's default device node names, as that would
+ result in unpredictable behavior.
</para>
</listitem>
</varlistentry>
<term><option>ENV{<replaceable>key</replaceable>}</option></term>
<listitem>
<para>Set a device property value. Property names with a leading '.'
- are not stored in the database or exported to external tool or events.</para>
+ are neither stored in the database nor exported to events or
+ external tools (run by, say, the PROGRAM match key).</para>
</listitem>
</varlistentry>
this or a dependent device. Long running tasks need to be immediately
detached from the event process itself.</para>
<para>If no absolute path is given, the program is expected to live in
- <filename>/lib/udev</filename>, otherwise the absolute path must be
- specified. Program name and arguments are separated by spaces. Single quotes
- can be used to specify arguments with spaces.</para>
+ the directory provided at compile-time to configure via --libexecdir
+ (this is usually <filename>/lib/udev</filename>), otherwise the absolute
+ path must be specified. The program name and following arguments are
+ separated by spaces. Single quotes can be used to specify arguments with
+ spaces.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>LABEL</option></term>
<listitem>
- <para>Named label where a GOTO can jump to.</para>
+ <para>A named label to which a GOTO may jump.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>GOTO</option></term>
<listitem>
- <para>Jumps to the next LABEL with a matching name</para>
+ <para>Jumps to the next LABEL with a matching name.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>file</option></term>
<listitem>
- <para>Import a text file specified as the assigned value, which must be in
- environment key format.</para>
+ <para>Import a text file specified as the assigned value, the content
+ of which must be in environment key format.</para>
</listitem>
</varlistentry>
<varlistentry>
<varlistentry>
<term><option>cmdline</option></term>
<listitem>
- <para>Import a single property from the kernel commandline. For simple flags
+ <para>Import a single property from the kernel command line. For simple flags
the value of the property is set to '1'.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>WAIT_FOR</option></term>
<listitem>
- <para>Wait for a file to become available or until a 10
- seconds timeout expires. The path is relative to the sysfs device,
- i. e. if no path is specified this waits for an attribute to appear.</para>
+ <para>Wait for a file to become available or until a timeout of
+ 10 seconds expires. The path is relative to the sysfs device;
+ if no path is specified, this waits for an attribute to appear.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>static_node=</option></term>
<listitem>
- <para>Apply the permissions specified in this rule to a static device node with
+ <para>Apply the permissions specified in this rule to the static device node with
the specified name. Static device nodes might be provided by kernel modules
or copied from <filename>/lib/udev/devices</filename>. These nodes might not have
a corresponding kernel device at the time udevd is started; they can trigger
<varlistentry>
<term><option>watch</option></term>
<listitem>
- <para>Watch the device node with inotify; when closed after being opened for
- writing, a change uevent is synthesised.</para>
+ <para>Watch the device node with inotify; when the node is closed after being opened for
+ writing, a change uevent is synthesized.</para>
</listitem>
</varlistentry>
<varlistentry>
<para>The <option>NAME</option>, <option>SYMLINK</option>, <option>PROGRAM</option>,
<option>OWNER</option>, <option>GROUP</option>, <option>MODE</option> and <option>RUN</option>
- fields support simple printf-like string substitutions. The <option>RUN</option>
- format chars gets applied after all rules have been processed, right before the program
- is executed. It allows the use of device properties set by earlier matching
- rules. For all other fields, substitutions are applied while the individual rule is
+ fields support simple string substitutions. The <option>RUN</option>
+ substitutions are performed after all rules have been processed, right before the program
+ is executed, allowing for the use of device properties set by earlier matching
+ rules. For all other fields, substitutions are performed while the individual rule is
being processed. The available substitutions are:</para>
<variablelist>
<varlistentry>
<para>The value of a sysfs attribute found at the device where
all keys of the rule have matched. If the matching device does not have
such an attribute, and a previous KERNELS, SUBSYSTEMS, DRIVERS, or
- ATTRS test selected a parent device, use the attribute from that
- parent device.
- If the attribute is a symlink, the last element of the symlink target is
+ ATTRS test selected a parent device, then the attribute from that
+ parent device is used.</para>
+ <para>If the attribute is a symlink, the last element of the symlink target is
returned as the value.</para>
</listitem>
</varlistentry>
<term><option>$result</option>, <option>%c</option></term>
<listitem>
<para>The string returned by the external program requested with PROGRAM.
- A single part of the string, separated by a space character may be selected
+ A single part of the string, separated by a space character, may be selected
by specifying the part number as an attribute: <option>%c{N}</option>.
- If the number is followed by the '+' char this part plus all remaining parts
+ If the number is followed by the '+' character, this part plus all remaining parts
of the result string are substituted: <option>%c{N+}</option></para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>$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>
<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>
~ianmdlvl / elogind.git / blobdiff