default rules directory <filename>/lib/udev/rules.d/</filename>,
the custom rules directory <filename>/etc/udev/rules.d/</filename>
and the temporary rules directory <filename>/run/udev/rules.d/</filename>.
- All rule files are sorted and processed in lexical order, regardless
- in which of these directories they live. Files in
- <filename>/etc/udev/rules.d/</filename> have precedence over files with
- the same name in <filename>/lib/udev/rules.d/</filename>. This can be
+ All rule files are collectively sorted and processed in lexical order,
+ regardless of the directories in which they live. However, files in
+ <filename>/etc/udev/rules.d/</filename> take precedence over files with
+ the same name in <filename>/lib/udev/rules.d/</filename>; this can be
used to ignore a default rules file if needed.</para>
- <para>Rule files must end in <filename>.rules</filename>, other extensions
- are ignored.</para>
+ <para>Rule files must have the extension <filename>.rules</filename>; other
+ extensions are ignored.</para>
- <para>Every line in the rules file contains at least one key value pair.
- There are two kind of keys, match and assignment keys.
+ <para>Every line in the rules file contains at least one key-value pair.
+ There are two kind of keys: match and assignment.
If all match keys are matching against its value, the rule gets applied and the
- assign keys get the specified value assigned.</para>
+ assignment keys get the specified value assigned.</para>
<para>A matching rule may rename a network interface, add symlinks
pointing to the device node, or run a specified program as part of
the event handling.</para>
- <para>A rule consists of a list of one or more key value pairs separated by
- a comma. Each key has a distinct operation, depending on the used operator. Valid
+ <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>
<varlistentry>
<term><option>:=</option></term>
<listitem>
- <para>Assign a value to a key finally; disallow any later changes,
- which may be used to prevent changes by any later rules.</para>
+ <para>Assign a value to a key finally; disallow any later changes.</para>
</listitem>
</varlistentry>
</variablelist>
<varlistentry>
<term><option>DRIVER</option></term>
<listitem>
- <para>Match the driver name of the event device. Only set for devices
+ <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>
<term><option>ATTR{<replaceable>filename</replaceable>}</option></term>
<listitem>
<para>Match sysfs attribute values of the event device. Trailing
- whitespace in the attribute values is ignored, if the specified match
- value does not contain trailing whitespace itself.
+ whitespace in the attribute values is ignored unless the specified match
+ value itself contains trailing whitespace.
</para>
</listitem>
</varlistentry>
<listitem>
<para>Search the devpath upwards for a device with matching sysfs attribute values.
If multiple <option>ATTRS</option> matches are specified, all of them
- must match on the same device. Trailing whitespace in the attribute values is ignored,
- if the specified match value does not contain trailing whitespace itself.</para>
+ must match on the same device. Trailing whitespace in the attribute values is ignored
+ unless the specified match value itself contains trailing whitespace.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>PROGRAM</option></term>
<listitem>
- <para>Execute a program. The key is true, if the program returns
+ <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 output printed to
- stdout, is available in the RESULT key.</para>
+ executed program in the environment. The program's stdout
+ is available in the RESULT key.</para>
</listitem>
</varlistentry>
</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>watch</option></term>
<listitem>
- <para>Watch the device node with inotify, when closed after being opened for
+ <para>Watch the device node with inotify; when closed after being opened for
writing, a change uevent is synthesised.</para>
</listitem>
</varlistentry>
~ianmdlvl / elogind.git / blobdiff