X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=udev.xml;h=5e5388da51cd691df38e56678f90b88ac5940e8e;hp=84341565300d6f02b8136cab04cb71854d66e066;hb=27283c2fdaefd9c7fd557fd4663566eacccca33a;hpb=95776dc6ec174f47fa4dd4d8abf5d457223e5dd4

diff --git a/udev.xml b/udev.xml
index 843415653..5e5388da5 100644
--- a/udev.xml
+++ b/udev.xml
@@ -174,7 +174,9 @@
                 <para>Match sysfs attribute values of the event device. Up to five
                 <option>ATTR</option> keys can be specified per rule. Trailing
                 whitespace in the attribute values is ignored, if the specified match
-                value does not contain trailing whitespace itself.</para>
+                value does not contain trailing whitespace itself. Depending on the type
+                of operator, this key is also used to set the value of a sysfs attribute.
+                </para>
               </listitem>
             </varlistentry>
 
@@ -213,8 +215,8 @@
               <term><option>ENV{<replaceable>key</replaceable>}</option></term>
               <listitem>
                 <para>Match against the value of an environment variable. Up to five <option>ENV</option>
-                keys can be specified per rule. This key can also be used to export a variable to
-                the environment.</para>
+                keys can be specified per rule. Depending on the type of operator, this key is also used
+                to export a variable to the environment.</para>
               </listitem>
             </varlistentry>
 
@@ -294,11 +296,20 @@
               </listitem>
             </varlistentry>
 
+            <varlistentry>
+              <term><option>ATTR{<replaceable>key</replaceable>}</option></term>
+              <listitem>
+                <para>The value that should be written to a sysfs attribute of the
+                event device. Depending on the type of operator, this key is also
+                used to match against the value of a sysfs attribute.</para>
+              </listitem>
+            </varlistentry>
+
             <varlistentry>
               <term><option>ENV{<replaceable>key</replaceable>}</option></term>
               <listitem>
-                <para>Export a variable to the environment. This key can also be used to match
-                against an environment variable.</para>
+                <para>Export a variable to the environment. Depending on the type of operator,
+                this key is also to match against an environment variable.</para>
               </listitem>
             </varlistentry>
 
@@ -330,11 +341,37 @@
             <varlistentry>
               <term><option>IMPORT{<replaceable>type</replaceable>}</option></term>
               <listitem>
-                <para>Import the printed result or the value of a file in environment key
-                format into the event environment. <option>program</option> will execute an
-                external program and read its output. <option>file</option> will import a
-                text file. If no option is given, udev will determine it from the  executable
-                bit of of the file permissions.</para>
+                <para>Import a set of variables into the event environment,
+                depending on <replaceable>type</replaceable>:</para>
+                <variablelist>
+                  <varlistentry>
+                    <term><option>program</option></term>
+                    <listitem>
+                      <para>Execute an external program specified as the assigned value and
+                      import its output, which must be in environment key format.</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>
+                    </listitem>
+                  </varlistentry>
+                  <varlistentry>
+                    <term><option>parent</option></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-style pattern matching used for
+                      comparisons).</para>
+                    </listitem>
+                  </varlistentry>
+                </variablelist>
+                <para>If no option is given, udev will choose between <option>program</option>
+                and <option>file</option> based on the executable bit of of the file
+                permissions.</para>
               </listitem>
             </varlistentry>
 
@@ -395,7 +432,7 @@
               <term><option>$id</option>, <option>%b</option></term>
               <listitem>
                 <para>The name of the device matched while searching the devpath upwards for
-                  <option>SUBSYSTEMS</option>, <option>KERNELS</option> <option>DRIVERS</option> and <option>ATTRS</option>.
+                  <option>SUBSYSTEMS</option>, <option>KERNELS</option>, <option>DRIVERS</option> and <option>ATTRS</option>.
                 </para>
               </listitem>
             </varlistentry>
@@ -403,7 +440,12 @@
             <varlistentry>
               <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term>
               <listitem>
-                <para>The value of a sysfs attribute found at the current or a parent device.</para>
+                <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, all devices along the chain of parents are searched
+                for a matching attribute.
+                If the attribute is a symlink, the last element of the symlink target is
+                returned as the value.</para>
               </listitem>
             </varlistentry>