alsactl_init.xml

ALSA驱动的一些调试测试工具

                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <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.
                Depending on the type of operator, this key is also used
                to export a variable to the environment.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>PROGRAM</option></term>
              <listitem>
                <para>Execute external program. The key is true, if
                the program returns without exit code zero. The whole event
                environment is available to the executed program. The
                program's output printed to stdout is available for
                the RESULT key.</para>
                <para>Several buildin commands are available:</para>
                <variablelist>
                  <varlistentry>
                    <term><option>__ctl_search</option></term>
                    <listitem>
                      <para>Search for a control. The CTL{name} key might
		      contain match characters * and ?. An control index
		      might be specified as first argument starting from
		      zero (e.g. PROGRAM="__ctl_search 2").</para>
                     </listitem>
                  </varlistentry>
                  <varlistentry>
                    <term><option>__ctl_count</option></term>
                    <listitem>
                      <para>Search for a controls and return total count
                      of matched ones. The CTL{name} key might contain match
                      characters * and ?.</para>
                     </listitem>
                  </varlistentry>
		</variablelist>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>RESULT</option></term>
              <listitem>
                <para>Match the returned string of the last PROGRAM call.
                This key can be used in the same or in any later rule
                after a PROGRAM call.</para>
              </listitem>
            </varlistentry>

          </variablelist>

          <para>Most of the fields support a 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>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><option>?</option></term>
              <listitem>
                <para>Matches any single character.</para>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><option>[]</option></term>
              <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 be used. If the first character
      		following the '[' is a '!', any characters
                not enclosed are matched.</para>
              </listitem>
            </varlistentry>
          </variablelist>

          <para>The following keys can get values assigned:</para>
          <variablelist>
            <varlistentry>
              <term><option>CTL{numid}</option>, <option>CTL{iface}</option>,
		    <option>CTL{device}</option>, <option>CTL{subdev}</option>, 
		    <option>CTL{name}</option>,  <option>CTL{index}</option>, 
	      </term>
              <listitem>
              	 <para>Select universal control element.</para>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><option>CTL{value}</option></term>
              <listitem>
              	 <para>Value is set (written) also to soundcard's control
              	 device and RESULT key is set to errno code. The result of
                 set operation is always true (it means continue with
                 next key on line).</para>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><option>CTL{values}</option></term>
              <listitem>
              	 <para>Value is set (written) also to soundcard's control
              	 device (all control values are set to specified value) and
              	 RESULT key is set to errno code. The result of
                 set operation is always true (it means continue with
                 next key on line).</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>ENV{<replaceable>key</replaceable>}</option></term>
              <listitem>
                <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>

            <varlistentry>
              <term><option>RESULT</option></term>
              <listitem>
                <para>Set RESULT variable. Note that PROGRAM also sets
                this variable, but setting this variable manually
                might be useful to change code execution order (included
                files).</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>LABEL</option></term>
              <listitem>
                <para>Named label where a GOTO can jump to.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>GOTO</option></term>
              <listitem>
                <para>Jumps to the next LABEL with a matching name</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>INCLUDE</option></term>
              <listitem>
                <para>Include specified filename or all files in specified directory</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>ACCESS</option></term>
              <listitem>
                <para>Check if specified file or directory exists</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>CONFIG{sysfs_device}</option></term>
              <listitem>
                <para>The relative path to sysfs subsystem specifying
                the root directory of a soundcard device. Usually,
                it should be set to "/class/sound/controlC$cardinfo{card}/device".
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>PRINT</option></term>
              <listitem>
                <para>PRINT value to stdout.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>ERROR</option></term>
              <listitem>
                <para>PRINT value to stderr.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>EXIT</option></term>
              <listitem>
                <para>Exit immediately and set program exit code to value
                (should be integer). If value is "return" string,
                parser leaves current included file and returns to parent
                configuration file.</para>
              </listitem>
            </varlistentry>

          </variablelist>

          <para>The <option>PROGRAM</option>, <option>RESULT</option>,
          <option>CTL{value}</option>,
	  <option>PRINT</option>, <option>ERROR</option>,
	  <option>EXIT</option>, <option>CONFIG{}</option>
	  fields support simple printf-like string substitutions.
          It allows the use of the complete environment set by earlier matching
          rules. For all other fields, substitutions are applied while the individual rule is
          being processed. The available substitutions are:</para>
          <variablelist>
            <varlistentry>
	      <term><option>$cardinfo{<replaceable>attribute</replaceable>}</option>, <option>%i{<replaceable>attribute</replaceable>}</option></term>
              <listitem>
                <para>See CARDINFO{} for more details.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>$ctl{<replaceable>attribute</replaceable>}</option>, <option>%C{<replaceable>attribute</replaceable>}</option></term>
              <listitem>
                <para>See CTL{} for more details.</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 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>The value of an environment variable.</para>
              </listitem>
            </varlistentry>

            <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
                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
                of the result string are substituted: <option>%c{N+}</option></para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>$sysfsroot</option>, <option>%r</option></term>
              <listitem>
                <para>Root directory where sysfs file-system is mounted.
                Ususally, this value is just "/sys".</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>%%</option></term>
              <listitem>
              <para>The '%' character itself.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><option>$$</option></term>
              <listitem>
              <para>The '$' character itself.</para>
              </listitem>
            </varlistentry>
          </variablelist>
          <para>The count of characters to be substituted may be limited
          by specifying the format length value. For example, '%3s{file}'
          will only insert the first three characters of the sysfs
          attribute</para>
        </refsect2>
      </refsect1>

      <refsect1><title>AUTHOR</title>
        <para>Written by Jaroslav Kysela <email>[e-mail]</email></para>
        <para>Some portions are written by Greg Kroah-Hartman <email>[e-mail]</email> and
        Kay Sievers <email>[e-mail]</email>.</para>
      </refsect1>

      <refsect1>
        <title>SEE ALSO</title>
        <para><citerefentry>
            <refentrytitle>alsactl</refentrytitle><manvolnum>1</manvolnum>
          </citerefentry></para>
      </refsect1>
    </refentry>
  </section>
</article>