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<div id="preamble"><h1>Apache Module mod_log_config</h1>
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<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Logging of the requests made to the server</td></tr>
<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="module-dict.html#ModuleIdentifier">Module&nbsp;Identifier:</a></th><td>log_config_module</td></tr>
<tr><th><a href="module-dict.html#SourceFile">Source&nbsp;File:</a></th><td>mod_log_config.c</td></tr></table>
<h3>Summary</h3>

    <p>This module provides for flexible logging of client
    requests. Logs are written in a customizable format, and may be
    written directly to a file, or to an external program.
    Conditional logging is provided so that individual requests may
    be included or excluded from the logs based on characteristics
    of the request.</p>

    <p>Three directives are provided by this module:
    <code class="directive"><a href="#transferlog">TransferLog</a></code> to create
    a log file, <code class="directive"><a href="#logformat">LogFormat</a></code>
    to set a custom format, and <code class="directive"><a href="#customlog">CustomLog</a></code> to define a log file and format in one
    step. The <code class="directive">TransferLog</code> and <code class="directive">CustomLog</code> directives can be used multiple times in each
    server to cause each request to be logged to multiple files.</p>
</div>
<div id="quickview"><h3>Topics</h3>
<ul id="topics">
<li><img alt="" src="../images/down.gif"> <a href="#formats">Custom Log Formats</a></li>
<li><img alt="" src="../images/down.gif"> <a href="#security">Security Considerations</a></li>
</ul><h3 class="directives">Directives</h3>
<ul id="toc">
<li><img alt="" src="../images/down.gif"> <a href="#bufferedlogs">BufferedLogs</a></li>
<li><img alt="" src="../images/down.gif"> <a href="#customlog">CustomLog</a></li>
<li><img alt="" src="../images/down.gif"> <a href="#globallog">GlobalLog</a></li>
<li><img alt="" src="../images/down.gif"> <a href="#logformat">LogFormat</a></li>
<li><img alt="" src="../images/down.gif"> <a href="#transferlog">TransferLog</a></li>
</ul>
<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&amp;list_id=144532&amp;product=Apache%20httpd-2&amp;query_format=specific&amp;order=changeddate%20DESC%2Cpriority%2Cbug_severity&amp;component=mod_log_config">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&amp;component=mod_log_config">Report a bug</a></li></ul><h3>See also</h3>
<ul class="seealso">
<li><a href="../logs.html">Apache Log Files</a></li>
</ul></div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="section">
<h2 id="formats">Custom Log Formats <a title="Permanent link" href="#formats" class="permalink">&para;</a></h2>

    <p>The format argument to the <code class="directive"><a href="#logformat">LogFormat</a></code> and <code class="directive"><a href="#customlog">CustomLog</a></code> directives is a string. This string is
    used to log each request to the log file. It can contain literal
    characters copied into the log files and the C-style control
    characters "\n" and "\t" to represent new-lines and tabs.
    Literal quotes and backslashes should be escaped with
    backslashes.</p>

    <p>The characteristics of the request itself are logged by
    placing "<code>%</code>" directives in the format string, which are
    replaced in the log file by the values as follows:</p>

    <table class="bordered"><tr class="header"><th>Format&nbsp;String</th>
        <th>Description</th></tr>
<tr><td><code>%%</code></td>
        <td>The percent sign.</td></tr>
<tr class="odd"><td><code>%a</code></td>
        <td>Client IP address of the request (see the
        <code class="module"><a href="../mod/mod_remoteip.html">mod_remoteip</a></code> module).</td></tr>
<tr><td><code>%{c}a</code></td>
        <td>Underlying peer IP address of the connection (see the
        <code class="module"><a href="../mod/mod_remoteip.html">mod_remoteip</a></code> module).</td></tr>
<tr class="odd"><td><code>%A</code></td>
        <td>Local IP-address.</td></tr>
<tr><td><code>%B</code></td>
        <td>Size of response in bytes, excluding HTTP headers.</td></tr>
<tr class="odd"><td><code>%b</code></td>
        <td>Size of response in bytes, excluding HTTP headers. In CLF format, <em>i.e.</em>
        a '<code>-</code>' rather than a 0 when no bytes are sent.</td></tr>
<tr><td><code>%{<var>VARNAME</var>}C</code></td>
        <td>The contents of cookie <var>VARNAME</var> in the request sent
        to the server. Only version 0 cookies are fully supported.</td></tr>
<tr class="odd"><td><code>%D</code></td>
        <td>The time taken to serve the request, in microseconds.</td></tr>
<tr><td><code>%{<var>VARNAME</var>}e</code></td>
        <td>The contents of the environment variable
        <var>VARNAME</var>.</td></tr>
<tr class="odd"><td><code>%f</code></td>
        <td>Filename.</td></tr>
<tr><td><code>%h</code></td>
        <td>Remote hostname. Will log the IP address if <code class="directive"><a href="../mod/core.html#hostnamelookups">HostnameLookups</a></code> is set to
        <code>Off</code>, which is the default. If it logs the hostname
        for only a few hosts, you probably have access control
        directives mentioning them by name. See <a href="mod_authz_host.html#reqhost">the Require host
        documentation</a>.</td></tr>
<tr class="odd"><td><code>%{c}h</code></td>
        <td>Like <code>%h</code>, but always reports on the hostname of the
        underlying TCP connection and not any modifications to the 
        remote hostname by modules like <code class="module"><a href="../mod/mod_remoteip.html">mod_remoteip</a></code>.</td></tr>
<tr><td><code>%H</code></td>
        <td>The request protocol.</td></tr>
<tr class="odd"><td><code>%{<var>VARNAME</var>}i</code></td>
        <td>The contents of <code><var>VARNAME</var>:</code> header line(s)
        in the request sent to the server. Changes made by other
        modules (e.g. <code class="module"><a href="../mod/mod_headers.html">mod_headers</a></code>) affect this.  If you're
        interested in what the request header was prior to when most
        modules would have modified it, use <code class="module"><a href="../mod/mod_setenvif.html">mod_setenvif</a></code>
        to copy the header into an internal environment variable and log
        that value with the <code>%{<var>VARNAME</var>}e</code> described
        above.
        </td></tr>
<tr><td><code>%k</code></td>
        <td>Number of keepalive requests handled on this connection.  Interesting if
          <code class="directive"><a href="../mod/core.html#keepalive">KeepAlive</a></code> is being used, so that,
          for example, a '1' means the first keepalive request after the initial
          one, '2' the second, etc...;
          otherwise this is always 0 (indicating the initial request).</td></tr>
<tr class="odd"><td><code>%l</code></td>
        <td>Remote logname (from identd, if supplied). This will return a
        dash unless <code class="module"><a href="../mod/mod_ident.html">mod_ident</a></code> is present and <code class="directive"><a href="../mod/mod_ident.html#identitycheck">IdentityCheck</a></code> is set
        <code>On</code>.</td></tr>
<tr><td><code>%L</code></td>
        <td>The request log ID from the error log (or '-' if nothing has been
            logged to the error log for this request). Look for the
            matching error log line to see what request caused what error.</td></tr>
<tr class="odd"><td><code>%m</code></td>
        <td>The request method.</td></tr>
<tr><td><code>%{<var>VARNAME</var>}n</code></td>
        <td>The contents of note <var>VARNAME</var> from another
        module.</td></tr>
<tr class="odd"><td><code>%{<var>VARNAME</var>}o</code></td>
        <td>The contents of <code><var>VARNAME</var>:</code> header line(s)
        in the reply.</td></tr>
<tr><td><code>%p</code></td>
        <td>The canonical port of the server serving the request.</td></tr>
<tr class="odd"><td><code>%{<var>format</var>}p</code></td>
        <td>The canonical port of the server serving the request, or the
        server's actual port, or the client's actual port. Valid formats
        are <code>canonical</code>, <code>local</code>, or <code>remote</code>.
        </td></tr>
<tr><td><code>%P</code></td>
        <td>The process ID of the child that serviced the request.</td></tr>
<tr class="odd"><td><code>%{<var>format</var>}P</code></td>
        <td>The process ID or thread ID of the child that serviced the
        request.  Valid formats are <code>pid</code>, <code>tid</code>,
        and <code>hextid</code>.
        </td></tr>
<tr><td><code>%q</code></td>
        <td>The query string (prepended with a <code>?</code> if a query
        string exists, otherwise an empty string).</td></tr>
<tr class="odd"><td><code>%r</code></td>
        <td>First line of request. Does not adhere to 
        <code class="directive"><a href="../mod/core.html#mergeslashes">MergeSlashes</a></code>. (i.e. no merging
        even if ON)</td></tr>
<tr><td><code>%R</code></td>
        <td>The handler generating the response (if any).</td></tr>
<tr class="odd"><td><code>%s</code></td>
        <td>Status. For requests that have been internally redirected, this is
        the status of the <em>original</em> request. Use <code>%&gt;s</code>
        for the final status.</td></tr>
<tr><td><code>%t</code></td>
        <td>Time the request was received, in the format <code>[18/Sep/2011:19:18:28 -0400]</code>.
        The last number indicates the timezone offset from GMT</td></tr>
<tr class="odd"><td><code>%{<var>format</var>}t</code></td>
        <td>The time, in the form given by format, which should be in
        an extended <code>strftime(3)</code> format (potentially localized).
        If the format starts with <code>begin:</code> (default) the time is taken
        at the beginning of the request processing. If it starts with
        <code>end:</code> it is the time when the log entry gets written,
        close to the end of the request processing. In addition to the formats
        supported by <code>strftime(3)</code>, the following format tokens are
        supported:
        <table>
        <tr><td><code>sec</code></td><td>number of seconds since the Epoch</td></tr>
        <tr><td><code>msec</code></td><td>number of milliseconds since the Epoch</td></tr>
        <tr><td><code>usec</code></td><td>number of microseconds since the Epoch</td></tr>
        <tr><td><code>msec_frac</code></td><td>millisecond fraction</td></tr>
        <tr><td><code>usec_frac</code></td><td>microsecond fraction</td></tr>
        </table>
        These tokens can not be combined with each other or <code>strftime(3)</code>
        formatting in the same format string. You can use multiple
        <code>%{<var>format</var>}t</code> tokens instead.
        </td></tr>
<tr><td><code>%T</code></td>
        <td>The time taken to serve the request, in seconds.</td></tr>
<tr class="odd"><td><code>%{<var>UNIT</var>}T</code></td>
        <td>The time taken to serve the request, in a time unit given by
        <code>UNIT</code>. Valid units are <code>ms</code> for milliseconds,
        <code>us</code> for microseconds, and <code>s</code> for seconds.
        Using <code>s</code> gives the same result as <code>%T</code>
        without any format; using <code>us</code> gives the same result
        as <code>%D</code>. Combining <code>%T</code> with a unit is
        available in 2.4.13 and later.</td></tr>
<tr><td><code>%u</code></td>
        <td>Remote user if the request was authenticated. May be bogus if return status
        (<code>%s</code>) is 401 (unauthorized).</td></tr>
<tr class="odd"><td><code>%U</code></td>
        <td>The URL path requested, not including any query string. 
        Adheres to <code class="directive"><a href="../mod/core.html#mergeslashes">MergeSlashes</a></code>.
        (i.e. slashes are merged if <code>ON</code>)</td></tr>
<tr><td><code>%v</code></td>
        <td>The canonical <code class="directive"><a href="../mod/core.html#servername">ServerName</a></code>
        of the server serving the request.</td></tr>
<tr class="odd"><td><code>%V</code></td>
        <td>The server name according to the <code class="directive"><a href="../mod/core.html#usecanonicalname">UseCanonicalName</a></code> setting.</td></tr>
<tr><td><code>%X</code></td>
        <td>Connection status when response is completed:

        <table>
        
        <tr><td><code>X</code> =</td>
            <td>Connection aborted before the response completed.</td></tr>
        <tr><td><code>+</code> =</td>
            <td>Connection may be kept alive after the response is
            sent.</td></tr>
        <tr><td><code>-</code> = </td>
            <td>Connection will be closed after the response is
            sent.</td></tr>
        </table>

        </td></tr>
<tr class="odd"><td><code>%I</code></td>
        <td>Bytes received, including request and headers. Cannot be zero.
        You need to enable <code class="module"><a href="../mod/mod_logio.html">mod_logio</a></code> to use this.</td></tr>
<tr><td><code>%O</code></td>
        <td>Bytes sent, including headers. May be zero in rare cases
        such as when a request is aborted before a response is sent.
        You need to enable <code class="module"><a href="../mod/mod_logio.html">mod_logio</a></code> to use this.</td></tr>
<tr class="odd"><td><code>%S</code></td>
        <td>Bytes transferred (received and sent), including request and headers,
        cannot be zero. This is the combination of %I and %O. You need to
        enable <code class="module"><a href="../mod/mod_logio.html">mod_logio</a></code> to use this.</td></tr>
<tr><td><code>%{<var>VARNAME</var>}^ti</code></td>
        <td>The contents of <code><var>VARNAME</var>:</code> trailer line(s)
        in the request sent to the server.  </td></tr>
<tr class="odd"><td><code>%{<var>VARNAME</var>}^to</code></td>
        <td>The contents of <code><var>VARNAME</var>:</code> trailer line(s)
        in the response sent from the server.  </td></tr>
</table>

    <h3 id="modifiers">Modifiers</h3>

      <p>Particular items can be restricted to print only for
      responses with specific HTTP status codes by placing a
      comma-separated list of status codes immediately following the
      "%". The status code list may be preceded by a "<code>!</code>" to
      indicate negation.</p>

    <table class="bordered"><tr class="header"><th>Format String</th>
    <th>Meaning</th></tr>
<tr>
    <td><code>%400,501{User-agent}i</code></td>
    <td>Logs <code>User-agent</code> on 400 errors and 501 errors only. For
      other status codes, the literal string <code>"-"</code> will be
      logged.</td></tr>
<tr class="odd"><td><code>%!200,304,302{Referer}i</code></td>
    <td>Logs <code>Referer</code> on all requests that do
    <em>not</em> return one of the three specified codes,
    "<code>-</code>" otherwise.
    </td></tr>
</table>

      <p>The modifiers "&lt;" and "&gt;" can be used for requests that
      have been internally redirected to choose whether the original
      or final (respectively) request should be consulted.  By
      default, the <code>%</code> directives <code>%s, %U, %T,
      %D,</code> and <code>%r</code> look at the original request
      while all others look at the final request.  So for example,
      <code>%&gt;s</code> can be used to record the final status of
      the request and <code>%&lt;u</code> can be used to record the
      original authenticated user on a request that is internally
      redirected to an unauthenticated resource.</p>

    

    <h3 id="format-notes">Format Notes</h3>

      <p>For security reasons, starting with version 2.0.46,
      non-printable and other special characters in format strings
      that may contain arbitrary string data are escaped using
      <code>\x<var>hh</var></code> sequences, where <var>hh</var>
      stands for the hexadecimal representation of the raw
      byte. Exceptions from this rule are <code>"</code> and
      <code>\</code>, which are escaped by prepending a backslash, and
      all whitespace characters, which are written in their C-style
      notation (<code>\n</code>, <code>\t</code>, etc).  In versions
      prior to 2.0.46, no escaping was performed on these strings so
      you had to be quite careful when dealing with raw log files.</p>

      <table>
      
      <tr><th>Format</th><th>Description</th><th>Escaped</th></tr>
      <tr><td><code>%C</code></td><td>Cookie value</td><td>Yes</td></tr>
      <tr><td><code>%e</code></td><td>Environment variable</td><td>Yes</td></tr>
      <tr><td><code>%f</code></td><td>Request filename</td><td>Yes</td></tr>
      <tr><td><code>%h</code></td><td>Remote hostname</td><td>Yes</td></tr>
      <tr><td><code>%H</code></td><td>Request protocol</td><td>Yes</td></tr>
      <tr><td><code>%i</code></td><td>Request header</td><td>Yes</td></tr>
      <tr><td><code>%l</code></td><td>Remote logname</td><td>Yes</td></tr>
      <tr><td><code>%m</code></td><td>Request method</td><td>Yes</td></tr>
      <tr><td><code>%n</code></td><td>Note</td><td>Yes</td></tr>
      <tr><td><code>%o</code></td><td>Response header</td><td>Yes</td></tr>
      <tr><td><code>%q</code></td><td>Query string</td><td>Yes</td></tr>
      <tr><td><code>%r</code></td><td>Request line</td><td>Yes</td></tr>
      <tr><td><code>%R</code></td><td>Handler</td><td>Yes</td></tr>
      <tr><td><code>%u</code></td><td>Remote user</td><td>Yes</td></tr>
      <tr><td><code>%U</code></td><td>Request URI</td><td>Yes</td></tr>
      <tr><td><code>%v</code></td><td>Server hostname</td><td>Yes</td></tr>
      <tr><td><code>%V</code></td><td>Canonical server name</td><td>Yes</td></tr>
      <tr><td><code>%^ti</code></td><td>Request trailer</td><td>Yes</td></tr>
      <tr><td><code>%^to</code></td><td>Response trailer</td><td>Yes</td></tr>
      <tr><td><code>%a</code></td><td>Remote IP address</td><td>No (IP address)</td></tr>
      <tr><td><code>%A</code></td><td>Local IP address</td><td>No (IP address)</td></tr>
      <tr><td><code>%b</code>, <code>%B</code></td><td>Bytes sent</td><td>No (numeric)</td></tr>
      <tr><td><code>%D</code></td><td>Request duration (microseconds)</td><td>No (numeric)</td></tr>
      <tr><td><code>%k</code></td><td>Requests on connection</td><td>No (numeric)</td></tr>
      <tr><td><code>%L</code></td><td>Log ID</td><td>No (internally generated)</td></tr>
      <tr><td><code>%p</code></td><td>Server port</td><td>No (numeric)</td></tr>
      <tr><td><code>%P</code></td><td>PID/TID</td><td>No (numeric)</td></tr>
      <tr><td><code>%s</code></td><td>Status code</td><td>No (numeric)</td></tr>
      <tr><td><code>%t</code></td><td>Request time</td><td>No (formatted time)</td></tr>
      <tr><td><code>%T</code></td><td>Request duration (seconds)</td><td>No (numeric)</td></tr>
      <tr><td><code>%X</code></td><td>Connection status</td><td>No (single character)</td></tr>
      </table>

      <p>The <code>%b</code> and
      <code>%B</code> format strings do not represent the number of
      bytes sent to the client, but simply the size in bytes of the
      HTTP response (which will differ, for instance, if the
      connection is aborted, or if SSL is used).  The <code>%O</code>
      format provided by <code class="module"><a href="../mod/mod_logio.html">mod_logio</a></code> will log the
      actual number of bytes sent over the network.</p>

      <div class="note">
      <p>Note: <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> is implemented as a
      quick-handler and not as a standard handler. Therefore, the
      <code>%R</code> format string will not return any handler
      information when content caching is involved.</p>
      </div>

    

    <h3 id="examples">Examples</h3>

      <p>Some commonly used log format strings are:</p>

      <dl>
        <dt>Common Log Format (CLF)</dt>
        <dd><code>"%h %l %u %t \"%r\" %&gt;s %b"</code></dd>

        <dt>Common Log Format with Virtual Host</dt>
        <dd><code>"%v %h %l %u %t \"%r\" %&gt;s %b"</code></dd>

        <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>You can use the <code>%{format}t</code> directive multiple
      times to build up a time format using the extended format tokens
      like <code>msec_frac</code>:</p>
      <dl>
<dt>Timestamp including milliseconds</dt>
<dd><code>"%{%d/%b/%Y %T}t.%{msec_frac}t %{%z}t"</code></dd>

      </dl>

    
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="section">
<h2 id="security">Security Considerations <a title="Permanent link" href="#security" class="permalink">&para;</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 id="bufferedlogs"><span id="BufferedLogs">BufferedLogs</span> Directive <a title="Permanent link" href="#bufferedlogs" class="permalink">&para;</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>
</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 should be used with caution as a crash might
    cause loss of logging data.</div>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="directive-section"><h2 id="customlog"><span id="CustomLog">CustomLog</span> Directive <a title="Permanent link" href="#customlog" class="permalink">&para;</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>|
expr=<var>expression</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. See the notes on <a href="../logs.html#piped">piped logs</a>
      for more information.

      <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>

    <pre class="prettyprint lang-config"># CustomLog with format nickname
LogFormat "%h %l %u %t \"%r\" %&gt;s %b" common
CustomLog "logs/access_log" common

# CustomLog with explicit format string
CustomLog "logs/access_log" "%h %l %u %t \"%r\" %&gt;s %b"</pre>


    <p>The third argument is optional and controls whether or
    not to log a particular request. The condition can be the
    presence or absence (in the case of a '<code>env=!<var>name</var></code>'
    clause) of a particular variable in the server
    <a href="../env.html">environment</a>. Alternatively, the condition
    can be expressed as arbitrary boolean <a href="../expr.html">expression</a>. If the condition is not satisfied, the request
    will not be logged. References to HTTP headers  in the expression
    will not cause the header names to be added to the Vary header.</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>

    <pre class="prettyprint lang-config">SetEnvIf Request_URI \.gif$ gif-image
CustomLog "gif-requests.log" common env=gif-image
CustomLog "nongif-requests.log" common env=!gif-image</pre>


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

    <pre class="prettyprint lang-config">SetEnvIf Referer example\.com localreferer
CustomLog "referer.log" referer env=!localreferer</pre>


</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="directive-section"><h2 id="globallog"><span id="GlobalLog">GlobalLog</span> Directive <a title="Permanent link" href="#globallog" class="permalink">&para;</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>GlobalLog <var>file</var>|<var>pipe</var>
<var>format</var>|<var>nickname</var>
[env=[!]<var>environment-variable</var>|
expr=<var>expression</var>]</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 Apache HTTP Server 2.4.19 and later</td></tr>
</table>

    <p>The <code class="directive">GlobalLog</code> directive defines a log shared
       by the main server configuration and all defined virtual hosts.</p>

    <p>The <code class="directive">GlobalLog</code> directive is identical to
    the <code class="directive">CustomLog</code> directive, apart from the following
    differences:</p>
    <ul>
       <li><code class="directive">GlobalLog</code> is not valid in virtual host
            context.</li>
       <li><code class="directive">GlobalLog</code> is used by virtual hosts that
           define their own <code class="directive">CustomLog</code>, unlike a 
           globally specified <code class="directive">CustomLog</code>.</li>
    </ul>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="directive-section"><h2 id="logformat"><span id="LogFormat">LogFormat</span> Directive <a title="Permanent link" href="#logformat" class="permalink">&para;</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><pre class="prettyprint lang-config">LogFormat "%v %h %l %u %t \"%r\" %&gt;s %b" vhost_common</pre>
</div>


</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="directive-section"><h2 id="transferlog"><span id="TransferLog">TransferLog</span> Directive <a title="Permanent link" href="#transferlog" class="permalink">&para;</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><pre class="prettyprint lang-config">LogFormat "%h %l %u %t \"%r\" %&gt;s %b \"%{Referer}i\" \"%{User-agent}i\""
TransferLog "logs/access_log"</pre>
</div>

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