<dt>NCSA extended/combined log format</dt>
      <dd><code>"%h %l %u %t \"%r\" %&gt;s %b \"%{Referer}i\"
      \"%{User-agent}i\""</code></dd>

      <dt>Referer log format</dt>
      <dd><code>"%{Referer}i -&gt; %U"</code></dd>

      <dt>Agent (Browser) log format</dt>
      <dd><code>"%{User-agent}i"</code></dd>
    </dl>

    <p>Note that the canonical <code class="directive"><a href="../mod/core.html#servername">ServerName</a></code> and <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code> of the server serving the
    request are used for <code>%v</code> and <code>%p</code>
    respectively. This happens regardless of the <code class="directive"><a href="../mod/core.html#usecanonicalname">UseCanonicalName</a></code> setting
    because otherwise log analysis programs would have to duplicate
    the entire vhost matching algorithm in order to decide what
    host really served the request.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="security" id="security">Security Considerations</a></h2>
    <p>See the <a href="../misc/security_tips.html#serverroot">security tips</a>
    document for details on why your security could be compromised
    if the directory where logfiles are stored is writable by
    anyone other than the user that starts the server.</p>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="BufferedLogs" id="BufferedLogs">BufferedLogs</a> <a name="bufferedlogs" id="bufferedlogs">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Buffer log entries in memory before writing to disk</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>BufferedLogs On|Off</code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>BufferedLogs Off</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_log_config</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in versions 2.0.41 and later.</td></tr>
</table>
    <p>The <code class="directive">BufferedLogs</code> directive causes
    <code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code> to store several log entries in
    memory and write them together to disk, rather than writing them
    after each request.  On some systems, this may result in more
    efficient disk access and hence higher performance.  It may be
    set only once for the entire server; it cannot be configured
    per virtual-host.</p>

    <div class="note">This directive is experimental and should be used with
    caution.</div>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="CookieLog" id="CookieLog">CookieLog</a> <a name="cookielog" id="cookielog">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets filename for the logging of cookies</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CookieLog <var>filename</var></code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_log_config</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>This directive is deprecated.</td></tr>
</table>
    <p>The <code class="directive">CookieLog</code> directive sets the 
    filename for logging of cookies. The filename is relative to the
    <code class="directive"><a href="../mod/core.html#serverroot">ServerRoot</a></code>. This directive is
    included only for compatibility with <code>mod_cookies</code>,
    and is deprecated.</p>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="CustomLog" id="CustomLog">CustomLog</a> <a name="customlog" id="customlog">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets filename and format of log file</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CustomLog  <var>file</var>|<var>pipe</var>
<var>format</var>|<var>nickname</var>
[env=[!]<var>environment-variable</var>]</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_log_config</td></tr>
</table>
    <p>The <code class="directive">CustomLog</code> directive is used to
    log requests to the server. A log format is specified, and the
    logging can optionally be made conditional on request
    characteristics using environment variables.</p>

    <p>The first argument, which specifies the location to which
    the logs will be written, can take one of the following two
    types of values:</p>

    <dl>
      <dt><var>file</var></dt>
      <dd>A filename, relative to the <code class="directive"><a href="../mod/core.html#serverroot">ServerRoot</a></code>.</dd>

      <dt><var>pipe</var></dt>
      <dd>The pipe character "<code>|</code>", followed by the path
      to a program to receive the log information on its standard
      input.

      <div class="warning"><h3>Security:</h3>
      <p>If a program is used, then it will be run as the user who
      started <code class="program"><a href="../programs/httpd.html">httpd</a></code>. This will be root if the server was
      started by root; be sure that the program is secure.</p>
      </div>
      <div class="warning"><h3>Note</h3>
        <p>When entering a file path on non-Unix platforms, care should be taken
        to make sure that only forward slashed are used even though the platform
        may allow the use of back slashes. In general it is a good idea to always 
        use forward slashes throughout the configuration files.</p>
      </div></dd>
    </dl>

    <p>The second argument specifies what will be written to the
    log file. It can specify either a <var>nickname</var> defined by
    a previous <code class="directive"><a href="#logformat">LogFormat</a></code>
    directive, or it can be an explicit <var>format</var> string as
    described in the <a href="#formats">log formats</a> section.</p>

    <p>For example, the following two sets of directives have
    exactly the same effect:</p>

    <div class="example"><p><code>
      # CustomLog with format nickname<br />
      LogFormat "%h %l %u %t \"%r\" %&gt;s %b" common<br />
      CustomLog logs/access_log common<br />
      <br />
      # CustomLog with explicit format string<br />
      CustomLog logs/access_log "%h %l %u %t \"%r\" %&gt;s %b"
    </code></p></div>

    <p>The third argument is optional and controls whether or
    not to log a particular request based on the
    presence or absence of a particular variable in the server
    environment. If the specified <a href="../env.html">environment
    variable</a> is set for the request (or is not set, in the case
    of a '<code>env=!<var>name</var></code>' clause), then the
    request will be logged.</p>

    <p>Environment variables can be set on a per-request
    basis using the <code class="module"><a href="../mod/mod_setenvif.html">mod_setenvif</a></code>
    and/or <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> modules. For
    example, if you want to record requests for all GIF
    images on your server in a separate logfile but not in your main
    log, you can use:</p>
    
    <div class="example"><p><code>
      SetEnvIf Request_URI \.gif$ gif-image<br />
      CustomLog gif-requests.log common env=gif-image<br />
      CustomLog nongif-requests.log common env=!gif-image
    </code></p></div>

    <p>Or, to reproduce the behavior of the old RefererIgnore
    directive, you might use the following:</p>

    <div class="example"><p><code>
    SetEnvIf Referer example\.com localreferer<br />
    CustomLog referer.log referer env=!localreferer
    </code></p></div>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="LogFormat" id="LogFormat">LogFormat</a> <a name="logformat" id="logformat">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Describes a format for use in a log file</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogFormat <var>format</var>|<var>nickname</var>
[<var>nickname</var>]</code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LogFormat "%h %l %u %t \"%r\" %&gt;s %b"</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_log_config</td></tr>
</table>
    <p>This directive specifies the format of the access log
    file.</p>

    <p>The <code class="directive">LogFormat</code> directive can take one of two
    forms. In the first form, where only one argument is specified,
    this directive sets the log format which will be used by logs
    specified in subsequent <code class="directive">TransferLog</code>
    directives. The single argument can specify an explicit
    <var>format</var> as discussed in the <a href="#formats">custom log
    formats</a> section above. Alternatively, it can use a
    <var>nickname</var> to refer to a log format defined in a
    previous <code class="directive">LogFormat</code> directive as described
    below.</p>

    <p>The second form of the <code class="directive">LogFormat</code> 
    directive associates an explicit <var>format</var> with a
    <var>nickname</var>. This <var>nickname</var> can then be used in
    subsequent <code class="directive">LogFormat</code> or
    <code class="directive"><a href="#customlog">CustomLog</a></code> directives
    rather than repeating the entire format string. A
    <code class="directive">LogFormat</code> directive that defines a nickname
    <strong>does nothing else</strong> -- that is, it <em>only</em>
    defines the nickname, it doesn't actually apply the format and make
    it the default. Therefore, it will not affect subsequent
    <code class="directive"><a href="#transferlog">TransferLog</a></code> directives.
    In addition, <code class="directive">LogFormat</code> cannot use one nickname
    to define another nickname. Note that the nickname should not contain
    percent signs (<code>%</code>).</p>

    <div class="example"><h3>Example</h3><p><code>
      LogFormat "%v %h %l %u %t \"%r\" %&gt;s %b" vhost_common
    </code></p></div>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="TransferLog" id="TransferLog">TransferLog</a> <a name="transferlog" id="transferlog">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Specify location of a log file</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TransferLog <var>file</var>|<var>pipe</var></code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_log_config</td></tr>
</table>
    <p>This directive has exactly the same arguments and effect as
    the <code class="directive"><a href="#customlog">CustomLog</a></code>
    directive, with the exception that it does not allow the log format
    to be specified explicitly or for conditional logging of requests.
    Instead, the log format is determined by the most recently specified
    <code class="directive"><a href="#logformat">LogFormat</a></code> directive
    which does not define a nickname. Common Log Format is used if no
    other format has been specified.</p>

    <div class="example"><h3>Example</h3><p><code>
      LogFormat "%h %l %u %t \"%r\" %&gt;s %b \"%{Referer}i\" \"%{User-agent}i\""<br />
      TransferLog logs/access_log
    </code></p></div>

</div>
</div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="../en/mod/mod_log_config.html" title="English">&nbsp;en&nbsp;</a> |
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<a href="../ko/mod/mod_log_config.html" hreflang="ko" rel="alternate" title="Korean">&nbsp;ko&nbsp;</a></p>
</div><div id="footer">
<p class="apache">Copyright 2006 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
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