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From sl...@apache.org
Subject cvs commit: httpd-2.0/docs/manual logs.xml logs.html.en
Date Sat, 27 Jul 2002 17:18:50 GMT
slive       2002/07/27 10:18:50

  Modified:    docs/manual logs.html.en
  Added:       docs/manual logs.xml
  Log:
  New XML.
  
  Submitted by:	David Shane Holden <dpejesh@yahoo.com>
  
  Revision  Changes    Path
  1.10      +394 -494  httpd-2.0/docs/manual/logs.html.en
  
  Index: logs.html.en
  ===================================================================
  RCS file: /home/cvs/httpd-2.0/docs/manual/logs.html.en,v
  retrieving revision 1.9
  retrieving revision 1.10
  diff -u -d -b -u -r1.9 -r1.10
  --- logs.html.en	23 May 2002 07:47:36 -0000	1.9
  +++ logs.html.en	27 Jul 2002 17:18:50 -0000	1.10
  @@ -1,20 +1,8 @@
  -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
  -    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  -
  -<html xmlns="http://www.w3.org/1999/xhtml">
  -  <head>
  -    <meta name="generator" content="HTML Tidy, see www.w3.org" />
  -
  -    <title>Log Files - Apache HTTP Server</title>
  -  </head>
  -  <!-- Background white, links blue (unvisited), navy (visited), red (active) -->
  -
  -  <body bgcolor="#FFFFFF" text="#000000" link="#0000FF"
  -  vlink="#000080" alink="#FF0000">
  -    <!--#include virtual="header.html" -->
  -
  -    <h1 align="center">Log Files</h1>
  -
  +<html xmlns="http://www.w3.org/TR/xhtml1/strict"><head><!-- 
  +          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
  +                This file is generated from xml source: DO NOT EDIT
  +          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
  +        --><title>Log Files- Apache HTTP Server</title><link href="./style/manual.css" type="text/css" rel="stylesheet"/></head><body><blockquote><div align="center"><img src="./images/sub.gif" alt="[APACHE DOCUMENTATION]"/><h3>Apache HTTP Server Version 2.0</h3></div><h1 align="center">Log Files</h1>
       <p>In order to effectively manage a web server, it is necessary
       to get feedback about the activity and performance of the
       server as well as any problems that may be occuring. The Apache
  @@ -22,47 +10,8 @@
       capabilities. This document describes how to configure its
       logging capabilities, and how to understand what the logs
       contain.</p>
  +  <ul><li><a href="#security">Security Warning</a></li><li><a href="#errorlog">Error Log</a></li><li><a href="#accesslog">Access Log</a><ul><li><a href="#common">Common Log Format</a></li><li><a href="#combined">Combined Log Format</a></li><li><a href="#multiple">Multiple Access Logs</a></li><li><a href="#conditional">Conditional Logs</a></li></ul></li><li><a href="#rotation">Rotation Logs</a></li><li><a href="#piped">Piped Logs</a></li><li><a href="#virtualhost">Virtual Hosts</a></li><li><a href="#other">Other Log Files</a><ul><li><a href="#pidfile">PID File</a></li><li><a href="#scriptlog">Script Log</a></li><li><a href="#rewritelog">Rewrite Log</a></li></ul></li></ul><hr/><h2><a name="security">Security Warning</a></h2>
   
  -    <ul>
  -      <li><a href="#security">Security Warning</a></li>
  -
  -      <li><a href="#errorlog">Error Log</a></li>
  -
  -      <li>
  -        <a href="#accesslog">Access Log</a> 
  -
  -        <ul>
  -          <li><a href="#common">Common Log Format</a></li>
  -
  -          <li><a href="#combined">Combined Log Format</a></li>
  -
  -          <li><a href="#multiple">Multiple Access Logs</a></li>
  -
  -          <li><a href="#conditional">Conditional Logging</a></li>
  -        </ul>
  -      </li>
  -
  -      <li><a href="#rotation">Log Rotation</a></li>
  -
  -      <li><a href="#piped">Piped Logs</a></li>
  -
  -      <li><a href="#virtualhosts">Virtual Hosts</a></li>
  -
  -      <li>
  -        <a href="#other">Other Log Files</a> 
  -
  -        <ul>
  -          <li><a href="#pidfile">PID File</a></li>
  -
  -          <li><a href="#scriptlog">Script Log</a></li>
  -
  -          <li><a href="#rewritelog">Rewrite Log</a></li>
  -        </ul>
  -      </li>
  -    </ul>
  -    <hr />
  -
  -    <h2><a id="security" name="security">Security Warning</a></h2>
   
       <p>Anyone who can write to the directory where Apache is
       writing a log file can almost certainly gain access to the uid
  @@ -77,21 +26,13 @@
       possible for malicious clients to insert control-characters in
       the log files, so care must be taken in dealing with raw
       logs.</p>
  -    <hr />
  +  <h2><a name="errorlog">Error Log</a></h2>
   
  -    <h2><a id="errorlog" name="errorlog">Error Log</a></h2>
   
  -    <table border="1">
  -      <tr>
  -        <td valign="top"><strong>Related Directives</strong><br />
  -         <br />
  -         <a href="mod/core.html#errorlog">ErrorLog</a><br />
  -         <a href="mod/core.html#loglevel">LogLevel</a> </td>
  -      </tr>
  -    </table>
  +    <table border="1"><tr><td valign="top"><strong>Related Modules</strong><br/><br/></td><td valign="top"><strong>Related Directives</strong><br/><br/><a href="./mod/mod_core.html#errorlog" class="directive"><code class="directive">ErrorLog</code></a><br/><a href="./mod/mod_core.html#loglevel" class="directive"><code class="directive">LogLevel</code></a><br/></td></tr></table>
   
       <p>The server error log, whose name and location is set by the
  -    <a href="mod/core.html#errorlog">ErrorLog</a> directive, is the
  +    <a href="./mod/core.html#errorlog" class="directive"><code class="directive">ErrorLog</code></a> directive, is the
       most important log file. This is the place where Apache httpd
       will send diagnostic information and record any errors that it
       encounters in processing requests. It is the first place to
  @@ -111,15 +52,15 @@
       in most error log entries. For example, here is a typical
       message.</p>
   
  -    <blockquote>
  -      <code>[Wed Oct 11 14:32:52 2000] [error] [client 127.0.0.1]
  +    <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +      [Wed Oct 11 14:32:52 2000] [error] [client 127.0.0.1]
         client denied by server configuration:
  -      /export/home/live/ap/htdocs/test</code>
  -    </blockquote>
  +      /export/home/live/ap/htdocs/test
  +    </code></td></tr></table></blockquote>
   
       <p>The first item in the log entry is the date and time of the
       message. The second entry lists the severity of the error being
  -    reported. The <a href="mod/core.html#loglevel">LogLevel</a>
  +    reported. The <a href="./mod/core.html#loglevel" class="directive"><code class="directive">LogLevel</code></a>
       directive is used to control the types of errors that are sent
       to the error log by restricting the severity level. The third
       entry gives the IP address of the client that generated the
  @@ -136,8 +77,7 @@
   
       <p>It is not possible to customize the error log by adding or
       removing information. However, error log entries dealing with
  -    particular requests have corresponding entries in the <a
  -    href="#accesslog">access log</a>. For example, the above example
  +    particular requests have corresponding entries in the <a href="#accesslog">access log</a>. For example, the above example
       entry corresponds to an access log entry with status code 403.
       Since it is possible to customize the access log, you can
       obtain more information about error conditions using that log
  @@ -147,39 +87,22 @@
       the error log for any problems. On unix systems, you can
       accomplish this using:</p>
   
  -    <blockquote>
  -      <code>tail -f error_log</code>
  -    </blockquote>
  -    <hr />
  -
  -    <h2><a id="accesslog" name="accesslog">Access Log</a></h2>
  +    <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +      tail -f error_log
  +    </code></td></tr></table></blockquote>
  +  <h2><a name="accesslog">Access Log</a></h2>
   
  -    <table border="1">
  -      <tr>
  -        <td valign="top"><strong>Related Modules</strong><br />
  -         <br />
  -         <a href="mod/mod_log_config.html">mod_log_config</a><br />
  -         </td>
   
  -        <td valign="top"><strong>Related Directives</strong><br />
  -         <br />
  -         <a
  -        href="mod/mod_log_config.html#customlog">CustomLog</a><br />
  -         <a
  -        href="mod/mod_log_config.html#logformat">LogFormat</a><br />
  -         <a href="mod/mod_setenvif.html#setenvif">SetEnvIf</a>
  -        </td>
  -      </tr>
  -    </table>
  +    <table border="1"><tr><td valign="top"><strong>Related Modules</strong><br/><br/><code><a href="./mod/mod_log_config.html">mod_log_config</a></code>, <br/><code><a href="./mod/mod_setenvif.html">mod_setenvif</a></code><br/></td><td valign="top"><strong>Related Directives</strong><br/><br/><a href="./mod/mod_log_config.html#customlog" class="directive"><code class="directive">CustomLog</code></a><br/><a href="./mod/mod_log_config.html#logformat" class="directive"><code class="directive">LogFormat</code></a><br/><a href="./mod/mod_setenvif.html#setenvif" class="directive"><code class="directive">SetEnvIf</code></a><br/></td></tr></table>
   
       <p>The server access log records all requests processed by the
       server. The location and content of the access log are
  -    controlled by the <a
  -    href="mod/mod_log_config.html#customlog">CustomLog</a>
  -    directive. The <a
  -    href="mod/mod_log_config.html#logformat">LogFormat</a>
  -    directive can be used to simplify the selection of the contents
  -    of the logs. This section describes how to configure the server
  +    controlled by the <a href="./mod/mod_log_config.html#
  +    customlog" class="directive"><code class="directive">
  +    CustomLog</code></a> directive. The <a href="./mod/mod_log_config.html#
  +    logformat" class="directive"><code class="directive">
  +    LogFormat</code></a> directive can be used to simplify the selection of 
  +    the contents of the logs. This section describes how to configure the server
       to record information in the access log.</p>
   
       <p>Of course, storing the information in the access log is only
  @@ -188,10 +111,8 @@
       general is beyond the scope of this document, and not really
       part of the job of the web server itself. For more information
       about this topic, and for applications which perform log
  -    analysis, check the <a
  -    href="http://dmoz.org/Computers/Software/Internet/Site_Management/Log_analysis/">
  -    Open Directory</a> or <a
  -    href="http://dir.yahoo.com/Computers_and_Internet/Software/Internet/World_Wide_Web/Servers/Log_Analysis_Tools/">
  +    analysis, check the <a href="http://dmoz.org/Computers/Software/Internet/Site_Management/Log_analysis/">
  +    Open Directory</a> or <a href="http://dir.yahoo.com/Computers_and_Internet/Software/Internet/World_Wide_Web/Servers/Log_Analysis_Tools/">
       Yahoo</a>.</p>
   
       <p>Various versions of Apache httpd have used other modules and
  @@ -202,23 +123,24 @@
       directives.</p>
   
       <p>The format of the access log is highly configurable. The
  -    format is specified using a <a
  -    href="mod/mod_log_config.html#format">format string</a> that
  +    format is specified using a <a href="./mod/mod_log_config.html#
  +    customlog" class="directive"><code class="directive">
  +    CustomLog</code></a> that
       looks much like a C-style printf(1) format string. Some
       examples are presented in the next sections. For a complete
  -    list of the possible contents of the format string, see the <a
  -    href="mod/mod_log_config.html">mod_log_config
  +    list of the possible contents of the format string, see the <a href="mod/mod_log_config.html">mod_log_config
       documentation</a>.</p>
   
  -    <h3><a id="common" name="common">Common Log Format</a></h3>
  +    <h3><a name="common">Common Log Format</a></h3>
  +      
   
       <p>A typical configuration for the access log might look as
       follows.</p>
   
  -    <blockquote>
  -      <code>LogFormat "%h %l %u %t \"%r\" %&gt;s %b" common<br />
  -       CustomLog logs/access_log common</code>
  -    </blockquote>
  +      <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +        LogFormat "%h %l %u %t \"%r\" %&gt;s %b" common<br>
  +         CustomLog logs/access_log common
  +      </code></td></tr></table></blockquote>
   
       <p>This defines the <em>nickname</em> <code>common</code> and
       associates it with a particular log format string. The format
  @@ -234,8 +156,9 @@
   
       <p>The <code>CustomLog</code> directive sets up a new log file
       using the defined <em>nickname</em>. The filename for the
  -    access log is relative to the <a
  -    href="mod/core.html#serverroot">ServerRoot</a> unless it begins
  +      access log is relative to the <a href="./mod/core.html#
  +      serverroot" class="directive"><code class="directive">
  +      ServerRoot</code></a> unless it begins
       with a slash.</p>
   
       <p>The above configuration will write log entries in a format
  @@ -244,10 +167,10 @@
       analysis programs. The log file entries produced in CLF will
       look something like this:</p>
   
  -    <blockquote>
  -      <code>127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET
  -      /apache_pb.gif HTTP/1.0" 200 2326</code>
  -    </blockquote>
  +      <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +        127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET
  +        /apache_pb.gif HTTP/1.0" 200 2326
  +      </code></td></tr></table></blockquote>
   
       <p>Each part of this log entry is described below.</p>
   
  @@ -255,14 +178,14 @@
         <dt><code>127.0.0.1</code> (<code>%h</code>)</dt>
   
         <dd>This is the IP address of the client (remote host) which
  -      made the request to the server. If <a
  -      href="mod/core.html#hostnamelookups">HostnameLookups</a> is
  +        made the request to the server. If <a href="./mod/core.html#
  +        hostnamelookups" class="directive"><code class="directive">
  +        HostnameLookups</code></a> is
         set to <code>On</code>, then the server will try to determine
         the hostname and log it in place of the IP address. However,
         this configuration is not recommended since it can
         significantly slow the server. Instead, it is best to use a
  -      log post-processor such as <a
  -      href="programs/logresolve.html">logresolve</a> to determine
  +        log post-processor such as <a href="programs/logresolve.html">logresolve</a> to determine
         the hostnames. The IP address reported here is not
         necessarily the address of the machine at which the user is
         sitting. If a proxy server exists between the user and the
  @@ -278,8 +201,9 @@
         machine. This information is highly unreliable and should
         almost never be used except on tightly controlled internal
         networks. Apache httpd will not even attempt to determine
  -      this information unless <a
  -      href="mod/core.html#identitycheck">IdentityCheck</a> is set
  +        this information unless <a href="./mod/core.html#
  +        identitycheck" class="directive"><code class="directive">
  +        IdentityCheck</code></a> is set
         to <code>On</code>.</dd>
   
         <dt><code>frank</code> (<code>%u</code>)</dt>
  @@ -302,13 +226,13 @@
           The format is: 
   
           <blockquote>
  -          <code>[day/month/year:hour:minute:second zone]<br />
  -           day = 2*digit<br />
  -           month = 3*letter<br />
  -           year = 4*digit<br />
  -           hour = 2*digit<br />
  -           minute = 2*digit<br />
  -           second = 2*digit<br />
  +            <code>[day/month/year:hour:minute:second zone]<br>
  +             day = 2*digit<br>
  +             month = 3*letter<br>
  +             year = 4*digit<br>
  +             hour = 2*digit<br>
  +             minute = 2*digit<br>
  +             second = 2*digit<br>
              zone = (`+' | `-') 4*digit</code>
           </blockquote>
           It is possible to have the time displayed in another format
  @@ -339,8 +263,7 @@
         beginning in 2), a redirection (codes beginning in 3), an
         error caused by the client (codes beginning in 4), or an
         error in the server (codes beginning in 5). The full list of
  -      possible status codes can be found in the <a
  -      href="http://www.w3.org/Protocols/rfc2616/rfc2616.txt">HTTP
  +        possible status codes can be found in the <a href="http://www.w3.org/Protocols/rfc2616/rfc2616.txt">HTTP
         specification</a> (RFC2616 section 10).</dd>
   
         <dt><code>2326</code> (<code>%b</code>)</dt>
  @@ -352,17 +275,18 @@
         <code>%B</code> instead.</dd>
       </dl>
   
  -    <h4><a id="combined" name="combined">Combined Log
  -    Format</a></h4>
  +    
  +    <h3><a name="combined">Combined Log Format</a></h3>
  +      
   
       <p>Another commonly used format string is called the Combined
       Log Format. It can be used as follows.</p>
   
  -    <blockquote>
  -      <code>LogFormat "%h %l %u %t \"%r\" %&gt;s %b \"%{Referer}i\"
  -      \"%{User-agent}i\"" combined<br />
  -       CustomLog log/acces_log combined</code>
  -    </blockquote>
  +      <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +        LogFormat "%h %l %u %t \"%r\" %&gt;s %b \"%{Referer}i\"
  +        \"%{User-agent}i\"" combined<br>
  +         CustomLog log/acces_log combined
  +      </code></td></tr></table></blockquote>
   
       <p>This format is exactly the same as the Common Log Format,
       with the addition of two more fields. Each of the additional
  @@ -371,12 +295,12 @@
       any HTTP request header. The access log under this format will
       look like:</p>
   
  -    <blockquote>
  -      <code>127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET
  +      <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +        127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET
         /apache_pb.gif HTTP/1.0" 200 2326
         "http://www.example.com/start.html" "Mozilla/4.08 [en]
  -      (Win98; I ;Nav)"</code>
  -    </blockquote>
  +        (Win98; I ;Nav)"
  +      </code></td></tr></table></blockquote>
   
       <p>The additional fields are:</p>
   
  @@ -397,62 +321,66 @@
         itself.</dd>
       </dl>
   
  -    <h3><a id="multiple" name="multiple">Multiple Access
  -    Logs</a></h3>
  +    
  +    <h3><a name="multiple">Multiple Access Logs</a></h3>
  +      
   
       <p>Multiple access logs can be created simply by specifying
  -    multiple <code>CustomLog</code> directives in the configuration
  +      multiple <a href="./mod/core.html#customlog" class="directive"><code class="directive">CustomLog</code></a> 
  +      directives in the configuration
       file. For example, the following directives will create three
       access logs. The first contains the basic CLF information,
       while the second and third contain referer and browser
  -    information. The last two <code>CustomLog</code> lines show how
  -    to mimic the effects of the <code>ReferLog</code> and
  -    <code>AgentLog</code> directives.</p>
  +      information. The last two <a href="./mod/core.html#
  +      customlog" class="directive"><code class="directive">
  +      CustomLog</code></a> lines show how
  +      to mimic the effects of the <a href="./mod/core.html#referlog" class="directive"><code class="directive">ReferLog</code></a> 
  +      and <a href="./mod/core.html#agentlog" class="directive"><code class="directive">AgentLog</code></a> directives.</p>
   
  -    <blockquote>
  -      <code>LogFormat "%h %l %u %t \"%r\" %&gt;s %b" common<br />
  -       CustomLog logs/access_log common<br />
  -       CustomLog logs/referer_log "%{Referer}i -&gt; %U"<br />
  -       CustomLog logs/agent_log "%{User-agent}i"</code>
  -    </blockquote>
  +      <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +        LogFormat "%h %l %u %t \"%r\" %&gt;s %b" common<br>
  +        CustomLog logs/access_log common<br>
  +        CustomLog logs/referer_log "%{Referer}i -&gt; %U"<br>
  +        CustomLog logs/agent_log "%{User-agent}i"
  +      </code></td></tr></table></blockquote>
   
       <p>This example also shows that it is not necessary to define a
       nickname with the <code>LogFormat</code> directive. Instead,
       the log format can be specified directly in the
  -    <code>CustomLog</code> directive.</p>
  +      <a href="./mod/core.html#customlog" class="directive"><code class="directive">CustomLog</code></a> directive.</p>
  +    
  +    
  +    <h3><a name="conditional">Conditional Logs</a></h3>
   
  -    <h3><a id="conditional" name="conditional">Conditional
  -    Logging</a></h3>
   
       <p>There are times when it is convenient to exclude certain
       entries from the access logs based on characteristics of the
  -    client request. This is easily accomplished with the help of <a
  -    href="env.html">environment variables</a>. First, an
  +      client request. This is easily accomplished with the help of <a href="env.html">environment variables</a>. First, an
       environment variable must be set to indicate that the request
  -    meets certain conditions. This is usually accomplished with <a
  -    href="mod/mod_setenvif.html#setenvif">SetEnvIf</a>. Then the
  +      meets certain conditions. This is usually accomplished with 
  +      <a href="./mod/mod_setenvif.html#setenvif" class="directive"><code class="directive">SetEnvIf</code></a>. Then the
       <code>env=</code> clause of the <code>CustomLog</code>
       directive is used to include or exclude requests where the
       environment variable is set. Some examples:</p>
   
  -    <blockquote>
  -      <code># Mark requests from the loop-back interface<br />
  -       SetEnvIf Remote_Addr "127\.0\.0\.1" dontlog<br />
  -       # Mark requests for the robots.txt file<br />
  -       SetEnvIf Request_URI "^/robots\.txt$" dontlog<br />
  -       # Log what remains<br />
  -       CustomLog logs/access_log common env=!dontlog</code>
  -    </blockquote>
  +      <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +        # Mark requests from the loop-back interface<br>
  +        SetEnvIf Remote_Addr "127\.0\.0\.1" dontlog<br>
  +        # Mark requests for the robots.txt file<br>
  +        SetEnvIf Request_URI "^/robots\.txt$" dontlog<br>
  +        # Log what remains<br>
  +        CustomLog logs/access_log common env=!dontlog
  +      </code></td></tr></table></blockquote>
   
       <p>As another example, consider logging requests from
       english-speakers to one log file, and non-english speakers to a
       different log file.</p>
   
  -    <blockquote>
  -      <code>SetEnvIf Accept-Language "en" english<br />
  -       CustomLog logs/english_log common env=english<br />
  -       CustomLog logs/non_english_log common env=!english</code>
  -    </blockquote>
  +      <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +        SetEnvIf Accept-Language "en" english<br>
  +        CustomLog logs/english_log common env=english<br>
  +        CustomLog logs/non_english_log common env=!english
  +      </code></td></tr></table></blockquote>
   
       <p>Although we have just shown that conditional logging is very
       powerful and flexibly, it is not the only way to control the
  @@ -460,9 +388,9 @@
       contain a complete record of server activity. It is often
       easier to simply post-process the log files to remove requests
       that you do not want to consider.</p>
  -    <hr />
   
  -    <h2><a id="rotation" name="rotation">Log Rotation</a></h2>
  +  <h2><a name="rotation">Rotation Logs</a></h2>
  +    
   
       <p>On even a moderately busy server, the quantity of
       information stored in the log files is very large. The access
  @@ -471,8 +399,7 @@
       files by moving or deleting the existing logs. This cannot be
       done while the server is running, because Apache will continue
       writing to the old log file as long as it holds the file open.
  -    Instead, the server must be <a
  -    href="stopping.html">restarted</a> after the log files are
  +    Instead, the server must be <a href="stopping.html">restarted</a> after the log files are
       moved or deleted so that it will open new log files.</p>
   
       <p>By using a <em>graceful</em> restart, the server can be
  @@ -485,20 +412,18 @@
       scenario that simply rotates the logs and compresses the old
       logs to save space is:</p>
   
  -    <blockquote>
  -      <code>mv access_log access_log.old<br />
  -       mv error_log error_log.old<br />
  -       apachectl graceful<br />
  -       sleep 600<br />
  -       gzip access_log.old error_log.old</code>
  -    </blockquote>
  +    <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +      mv access_log access_log.old<br>
  +      mv error_log error_log.old<br>
  +      apachectl graceful<br>
  +      sleep 600<br>
  +      gzip access_log.old error_log.old
  +    </code></td></tr></table></blockquote>
   
  -    <p>Another way to perform log rotation is using <a
  -    href="#piped">piped logs</a> as discussed in the next
  +    <p>Another way to perform log rotation is using <a href="#piped">piped logs</a> as discussed in the next
       section.</p>
  -    <hr />
  +  <h2><a name="piped">Piped Logs</a></h2>
   
  -    <h2><a id="piped" name="piped">Piped Logs</a></h2>
   
       <p>Apache httpd is capable of writing error and access log
       files through a pipe to another process, rather than directly
  @@ -519,14 +444,14 @@
   
       <p>Some simple examples using piped logs:</p>
   
  -    <blockquote>
  -      <code># compressed logs<br />
  +    <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +      # compressed logs<br>
          CustomLog "|/usr/bin/gzip -c &gt;&gt;
  -      /var/log/access_log.gz" common<br />
  -       # almost-real-time name resolution<br />
  +      /var/log/access_log.gz" common<br>
  +      # almost-real-time name resolution<br>
          CustomLog "|/usr/local/apache/bin/logresolve &gt;&gt;
  -      /var/log/access_log" common</code>
  -    </blockquote>
  +      /var/log/access_log" common
  +    </code></td></tr></table></blockquote>
   
       <p>Notice that quotes are used to enclose the entire command
       that will be called for the pipe. Although these examples are
  @@ -535,15 +460,14 @@
   
       <p>One important use of piped logs is to allow log rotation
       without having to restart the server. The Apache HTTP Server
  -    includes a simple program called <a
  -    href="programs/rotatelogs.html">rotatelogs</a> for this
  +    includes a simple program called <a href="programs/rotatelogs.html">rotatelogs</a> for this
       purpose. For example, to rotate the logs every 24 hours, you
       can use:</p>
   
  -    <blockquote>
  -      <code>CustomLog "|/usr/local/apache/bin/rotatelogs
  -      /var/log/access_log 86400" common</code>
  -    </blockquote>
  +    <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +      CustomLog "|/usr/local/apache/bin/rotatelogs
  +      /var/log/access_log 86400" common
  +    </code></td></tr></table></blockquote>
   
       <p>A similar, but much more flexible log rotation program
       called <a href="http://www.cronolog.org/">cronolog</a>
  @@ -552,10 +476,8 @@
       <p>As with conditional logging, piped logs are a very powerful
       tool, but they should not be used where a simpler solution like
       off-line post-processing is available.</p>
  -    <hr />
  +  <h2><a name="virtualhost">Virtual Hosts</a></h2>
   
  -    <h2><a id="virtualhosts" name="virtualhosts">Virtual
  -    Hosts</a></h2>
   
       <p>When running a server with many <a href="vhosts/">virtual
       hosts</a>, there are several options for dealing with log
  @@ -567,16 +489,18 @@
       for easy collection of statistics on individual virtual
       hosts.</p>
   
  -    <p>If <code>CustomLog</code> or <code>ErrorLog</code>
  -    directives are placed inside a <code>&lt;VirtualHost&gt;</code>
  +    <p>If <a href="./mod/mod_log_config.html#customlog" class="directive"><code class="directive">CustomLog</code></a> 
  +    or <a href="./mod/mod_log_config.html#errorlog" class="directive"><code class="directive">ErrorLog</code></a>
  +    directives are placed inside a <a href="./mod/core.html#
  +    <virtualhost>" class="directive"><code class="directive">
  +    &lt;VirtualHost&gt;</code></a>
       section, all requests or errors for that virtual host will be
       logged only to the specified file. Any virtual host which does
       not have logging directives will still have its requests sent
       to the main server logs. This technique is very useful for a
       small number of virtual hosts, but if the number of hosts is
       very large, it can be complicated to manage. In addition, it
  -    can often create problems with <a
  -    href="vhosts/fd-limits.html">insufficient file
  +    can often create problems with <a href="vhosts/fd-limits.html">insufficient file
       descriptors</a>.</p>
   
       <p>For the access log, there is a very good compromise. By
  @@ -585,82 +509,58 @@
       later split the log into individual files. For example,
       consider the following directives.</p>
   
  -    <blockquote>
  -      <code>LogFormat "%v %l %u %t \"%r\" %&gt;s %b"
  -      comonvhost<br />
  -       CustomLog logs/access_log comonvhost</code>
  -    </blockquote>
  +    <blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
  +      LogFormat "%v %l %u %t \"%r\" %&gt;s %b"
  +      comonvhost<br>
  +      CustomLog logs/access_log comonvhost
  +    </code></td></tr></table></blockquote>
   
       <p>The <code>%v</code> is used to log the name of the virtual
  -    host that is serving the request. Then a program like <a
  -    href="programs/other.html">split-logfile</a> can be used to
  +    host that is serving the request. Then a program like <a href="programs/other.html">split-logfile</a> can be used to
       post-process the access log in order to split it into one file
       per virtual host.</p>
  +  <h2><a name="other">Other Log Files</a></h2>
   
  -    <p>Unfortunately, no similar technique is available for the
  -    error log, so you must choose between mixing all virtual hosts
  -    in the same error log and using one error log per virtual
  -    host.</p>
  -    <hr />
  -
  -    <h2><a id="other" name="other">Other Log Files</a></h2>
   
  -    <table border="1">
  -      <tr>
  -        <td valign="top"><strong>Related Modules</strong><br />
  -         <br />
  -         <a href="mod/mod_cgi.html">mod_cgi</a><br />
  -         <a href="mod/mod_rewrite.html">mod_rewrite</a> </td>
  +    <table border="1"><tr><td valign="top"><strong>Related Modules</strong><br/><br/><code><a href="./mod/mod_cgi.html">mod_cgi</a></code>, <br/><code><a href="./mod/mod_rewrite.html">mod_rewrite</a></code><br/></td><td valign="top"><strong>Related Directives</strong><br/><br/><a href="./mod/core.html#pidfile" class="directive"><code class="directive">PidFile</code></a><br/><a href="./mod/mod_rewrite.html#rewritelog" class="directive"><code class="directive">RewriteLog</code></a><br/><a href="./mod/mod_rewrite.html#rewriteloglevel" class="directive"><code class="directive">RewriteLogLevel</code></a><br/><a href="./mod/mod_cgi.html#scriptlog" class="directive"><code class="directive">ScriptLog</code></a><br/><a href="./mod/mod_cgi.html#scriptloglength" class="directive"><code class="directive">ScriptLogLength</code></a><br/><a href="./mod/mod_cgi.html#scriptbuffer" class="directive"><code class="directive">ScriptBuffer</code></a><br/></td></tr></table>
   
  -        <td valign="top"><strong>Related Directives</strong><br />
  -         <br />
  -         <a href="mod/core.html#pidfile">PidFile</a><br />
  -         <a
  -        href="mod/mod_rewrite.html#RewriteLog">RewriteLog</a><br />
  -         <a
  -        href="mod/mod_rewrite.html#RewriteLogLevel">RewriteLogLevel</a><br />
  -         <a href="mod/mod_cgi.html#scriptlog">ScriptLog</a><br />
  -         <a
  -        href="mod/mod_cgi.html#scriptloglength">ScriptLogLength</a><br />
  -         <a
  -        href="mod/mod_cgi.html#scriptlogbuffer">ScriptLogBuffer</a>
  -        </td>
  -      </tr>
  -    </table>
  +    <h3><a name="pidfile">PID File</a></h3>
   
  -    <h3><a id="pidfile" name="pidfile">PID File</a></h3>
   
       <p>On startup, Apache httpd saves the process id of the parent
       httpd process to the file <code>logs/httpd.pid</code>. This
  -    filename can be changed with the <a
  -    href="mod/core.html#pidfile">PidFile</a> directive. The
  +      filename can be changed with the <a href="./mod/core.html#pidfile
  +      " class="directive"><code class="directive">PidFile
  +      </code></a> directive. The
       process-id is for use by the administrator in restarting and
       terminating the daemon by sending signals to the parent
       process; on Windows, use the -k command line option instead.
       For more information see the <a href="stopping.html">Stopping
       and Restarting</a> page.</p>
   
  -    <h3><a id="scriptlog" name="scriptlog">Script Log</a></h3>
   
  -    <p>In order to aid in debugging, the <a
  -    href="mod/mod_cgi.html#scriptlog">ScriptLog</a> directive
  +    <h3><a name="scriptlog">Script Log</a></h3>
  +      
  +      
  +      <p>In order to aid in debugging, the <a href="./mod/mod_cgi.html#
  +      scriptlog" class="directive"><code class="directive">
  +      ScriptLog</code></a> directive
       allows you to record the input to and output from CGI scripts.
       This should only be used in testing - not for live servers.
  -    More information is available in the <a
  -    href="mod/mod_cgi.html">mod_cgi documentation</a>.</p>
  +      More information is available in the <a href="mod/mod_cgi.html">mod_cgi documentation</a>.</p>
   
  -    <h3><a id="rewritelog" name="rewritelog">Rewrite Log</a></h3>
   
  -    <p>When using the powerful and complex features of <a
  -    href="mod/mod_rewrite.html">mod_rewrite</a>, it is almost
  -    always necessary to use the <a
  -    href="mod/mod_rewrite.html#RewriteLog">RewriteLog</a> to help
  +    <h3><a name="rewritelog">Rewrite Log</a></h3>
  +      
  +      
  +      <p>When using the powerful and complex features of <a href="mod/mod_rewrite.html">mod_rewrite</a>, it is almost
  +      always necessary to use the <a href="./mod/mod_rewrite.html#
  +      rewritelog" class="directive"><code class="directive">
  +      RewriteLog</code></a> to help
       in debugging. This log file produces a detailed analysis of how
       the rewriting engine transforms requests. The level of detail
  -    is controlled by the <a
  -    href="mod/mod_rewrite.html#RewriteLogLevel">RewriteLogLevel</a>
  -    directive.</p>
  -    <!--#include virtual="footer.html" -->
  -  </body>
  -</html>
  +      is controlled by the <a href="./mod/mod_rewrite.html#
  +      rewriteloglevel" class="directive"><code class="directive">
  +      RewriteLogLevel</code></a> directive.</p>
   
  +  </blockquote><hr/><h3 align="center">Apache HTTP Server Version 2.0</h3><a href="./"><img src="./images/index.gif" alt="Index"/></a><a href="./"><img src="./images/home.gif" alt="Home"/></a></body></html>
  \ No newline at end of file
  
  
  
  1.1                  httpd-2.0/docs/manual/logs.xml
  
  Index: logs.xml
  ===================================================================
  <?xml version="1.0" encoding="UTF-8" ?>
  <!DOCTYPE manualpage SYSTEM "./style/manualpage.dtd">
  <?xml-stylesheet type="text/xsl" href="./style/manual.en.xsl"?>
  
  <manualpage>
    <relativepath href="."/>
  
    <title>Log Files</title>
  
    <summary>
      <p>In order to effectively manage a web server, it is necessary
      to get feedback about the activity and performance of the
      server as well as any problems that may be occuring. The Apache
      HTTP Server provides very comprehensive and flexible logging
      capabilities. This document describes how to configure its
      logging capabilities, and how to understand what the logs
      contain.</p>
    </summary>
  
    <section id="security">
      <title>Security Warning</title>
      
      <p>Anyone who can write to the directory where Apache is
      writing a log file can almost certainly gain access to the uid
      that the server is started as, which is normally root. Do
      <em>NOT</em> give people write access to the directory the logs
      are stored in without being aware of the consequences; see the
      <a href="misc/security_tips.html">security tips</a> document
      for details.</p>
  
      <p>In addition, log files may contain information supplied
      directly by the client, without escaping. Therefore, it is
      possible for malicious clients to insert control-characters in
      the log files, so care must be taken in dealing with raw
      logs.</p>
    </section>
    
    <section id="errorlog">
      <title>Error Log</title>
      
      <related>
        <directivelist>
          <directive module="mod_core">ErrorLog</directive>
          <directive module="mod_core">LogLevel</directive>
        </directivelist>
      </related>
      
      <p>The server error log, whose name and location is set by the
      <directive module="core">ErrorLog</directive> directive, is the
      most important log file. This is the place where Apache httpd
      will send diagnostic information and record any errors that it
      encounters in processing requests. It is the first place to
      look when a problem occurs with starting the server or with the
      operation of the server, since it will often contain details of
      what went wrong and how to fix it.</p>
  
      <p>The error log is usually written to a file (typically
      <code>error_log</code> on unix systems and
      <code>error.log</code> on Windows and OS/2). On unix systems it
      is also possible to have the server send errors to
      <code>syslog</code> or <a href="#piped">pipe them to a
      program</a>.</p>
      
      <p>The format of the error log is relatively free-form and
      descriptive. But there is certain information that is contained
      in most error log entries. For example, here is a typical
      message.</p>
      
      <example>
        [Wed Oct 11 14:32:52 2000] [error] [client 127.0.0.1]
        client denied by server configuration:
        /export/home/live/ap/htdocs/test
      </example>
      
      <p>The first item in the log entry is the date and time of the
      message. The second entry lists the severity of the error being
      reported. The <directive module="core">LogLevel</directive>
      directive is used to control the types of errors that are sent
      to the error log by restricting the severity level. The third
      entry gives the IP address of the client that generated the
      error. Beyond that is the message itself, which in this case
      indicates that the server has been configured to deny the
      client access. The server reports the file-system path (as
      opposed to the web path) of the requested document.</p>
  
      <p>A very wide variety of different messages can appear in the
      error log. Most look similar to the example above. The error
      log will also contain debugging output from CGI scripts. Any
      information written to <code>stderr</code> by a CGI script will
      be copied directly to the error log.</p>
  
      <p>It is not possible to customize the error log by adding or
      removing information. However, error log entries dealing with
      particular requests have corresponding entries in the <a
      href="#accesslog">access log</a>. For example, the above example
      entry corresponds to an access log entry with status code 403.
      Since it is possible to customize the access log, you can
      obtain more information about error conditions using that log
      file.</p>
      
      <p>During testing, it is often useful to continuously monitor
      the error log for any problems. On unix systems, you can
      accomplish this using:</p>
      
      <example>
        tail -f error_log
      </example>
    </section>
    
    <section id="accesslog">
      <title>Access Log</title>
      
      <related>
        <modulelist>
          <module>mod_log_config</module>
          <module>mod_setenvif</module>
        </modulelist>
        <directivelist>
          <directive module="mod_log_config">CustomLog</directive>
          <directive module="mod_log_config">LogFormat</directive>
          <directive module="mod_setenvif">SetEnvIf</directive>
        </directivelist>
      </related>
      
      <p>The server access log records all requests processed by the
      server. The location and content of the access log are
      controlled by the <directive module="mod_log_config">
      CustomLog</directive> directive. The <directive module="mod_log_config">
      LogFormat</directive> directive can be used to simplify the selection of 
      the contents of the logs. This section describes how to configure the server
      to record information in the access log.</p>
  
      <p>Of course, storing the information in the access log is only
      the start of log management. The next step is to analyze this
      information to produce useful statistics. Log analysis in
      general is beyond the scope of this document, and not really
      part of the job of the web server itself. For more information
      about this topic, and for applications which perform log
      analysis, check the <a
      href="http://dmoz.org/Computers/Software/Internet/Site_Management/Log_analysis/">
      Open Directory</a> or <a
      href="http://dir.yahoo.com/Computers_and_Internet/Software/Internet/World_Wide_Web/Servers/Log_Analysis_Tools/">
      Yahoo</a>.</p>
      
      <p>Various versions of Apache httpd have used other modules and
      directives to control access logging, including
      mod_log_referer, mod_log_agent, and the
      <code>TransferLog</code> directive. The <code>CustomLog</code>
      directive now subsumes the functionality of all the older
      directives.</p>
  
      <p>The format of the access log is highly configurable. The
      format is specified using a <directive module="mod_log_config">
      CustomLog</directive> that
      looks much like a C-style printf(1) format string. Some
      examples are presented in the next sections. For a complete
      list of the possible contents of the format string, see the <a
      href="mod/mod_log_config.html">mod_log_config
      documentation</a>.</p>
      
      <section id="common">
        <title>Common Log Format</title>
      
        <p>A typical configuration for the access log might look as
        follows.</p>
  
        <example>
          LogFormat "%h %l %u %t \"%r\" %&gt;s %b" common<br />
           CustomLog logs/access_log common
        </example>
      
        <p>This defines the <em>nickname</em> <code>common</code> and
        associates it with a particular log format string. The format
        string consists of percent directives, each of which tell the
        server to log a particular piece of information. Literal
        characters may also be placed in the format string and will be
        copied directly into the log output. The quote character
        (<code>"</code>) must be escaped by placing a back-slash before
        it to prevent it from being interpreted as the end of the
        format string. The format string may also contain the special
        control characters "<code>\n</code>" for new-line and
        "<code>\t</code>" for tab.</p>
  
        <p>The <code>CustomLog</code> directive sets up a new log file
        using the defined <em>nickname</em>. The filename for the
        access log is relative to the <directive module="core">
        ServerRoot</directive> unless it begins
        with a slash.</p>
      
        <p>The above configuration will write log entries in a format
        known as the Common Log Format (CLF). This standard format can
        be produced by many different web servers and read by many log
        analysis programs. The log file entries produced in CLF will
        look something like this:</p>
  
        <example>
          127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET
          /apache_pb.gif HTTP/1.0" 200 2326
        </example>
      
        <p>Each part of this log entry is described below.</p>
      
        <dl>
          <dt><code>127.0.0.1</code> (<code>%h</code>)</dt>
  
          <dd>This is the IP address of the client (remote host) which
          made the request to the server. If <directive module="core">
          HostnameLookups</directive> is
          set to <code>On</code>, then the server will try to determine
          the hostname and log it in place of the IP address. However,
          this configuration is not recommended since it can
          significantly slow the server. Instead, it is best to use a
          log post-processor such as <a
          href="programs/logresolve.html">logresolve</a> to determine
          the hostnames. The IP address reported here is not
          necessarily the address of the machine at which the user is
          sitting. If a proxy server exists between the user and the
          server, this address will be the address of the proxy, rather
          than the originating machine.</dd>
  
          <dt><code>-</code> (<code>%l</code>)</dt>
  
          <dd>The "hyphen" in the output indicates that the requested
          piece of information is not available. In this case, the
          information that is not available is the RFC 1413 identity of
          the client determined by <code>identd</code> on the clients
          machine. This information is highly unreliable and should
          almost never be used except on tightly controlled internal
          networks. Apache httpd will not even attempt to determine
          this information unless <directive module="core">
          IdentityCheck</directive> is set
          to <code>On</code>.</dd>
  
          <dt><code>frank</code> (<code>%u</code>)</dt>
  
          <dd>This is the userid of the person requesting the document
          as determined by HTTP authentication. The same value is
          typically provided to CGI scripts in the
          <code>REMOTE_USER</code> environment variable. If the status
          code for the request (see below) is 401, then this value
          should not be trusted because the user is not yet
          authenticated. If the document is not password protected,
          this entry will be "<code>-</code>" just like the previous
          one.</dd>
  
          <dt><code>[10/Oct/2000:13:55:36 -0700]</code>
          (<code>%t</code>)</dt>
  
          <dd>
            The time that the server finished processing the request.
            The format is: 
  
            <blockquote>
              <code>[day/month/year:hour:minute:second zone]<br />
               day = 2*digit<br />
               month = 3*letter<br />
               year = 4*digit<br />
               hour = 2*digit<br />
               minute = 2*digit<br />
               second = 2*digit<br />
               zone = (`+' | `-') 4*digit</code>
            </blockquote>
            It is possible to have the time displayed in another format
            by specifying <code>%{format}t</code> in the log format
            string, where <code>format</code> is as in
            <code>strftime(3)</code> from the C standard library.
          </dd>
  
          <dt><code>"GET /apache_pb.gif HTTP/1.0"</code>
          (<code>\"%r\"</code>)</dt>
  
          <dd>The request line from the client is given in double
          quotes. The request line contains a great deal of useful
          information. First, the method used by the client is
          <code>GET</code>. Second, the client requested the resource
          <code>/apache_pb.gif</code>, and third, the client used the
          protocol <code>HTTP/1.0</code>. It is also possible to log
          one or more parts of the request line independently. For
          example, the format string "<code>%m %U%q %H</code>" will log
          the method, path, query-string, and protocol, resulting in
          exactly the same output as "<code>%r</code>".</dd>
  
          <dt><code>200</code> (<code>%&gt;s</code>)</dt>
  
          <dd>This is the status code that the server sends back to the
          client. This information is very valuable, because it reveals
          whether the request resulted in a successful response (codes
          beginning in 2), a redirection (codes beginning in 3), an
          error caused by the client (codes beginning in 4), or an
          error in the server (codes beginning in 5). The full list of
          possible status codes can be found in the <a
          href="http://www.w3.org/Protocols/rfc2616/rfc2616.txt">HTTP
          specification</a> (RFC2616 section 10).</dd>
  
          <dt><code>2326</code> (<code>%b</code>)</dt>
  
          <dd>The last entry indicates the size of the object returned
          to the client, not including the response headers. If no
          content was returned to the client, this value will be
          "<code>-</code>". To log "<code>0</code>" for no content, use
          <code>%B</code> instead.</dd>
        </dl>
      </section>
      
      <section id="combined">
        <title>Combined Log Format</title>
        
        <p>Another commonly used format string is called the Combined
        Log Format. It can be used as follows.</p>
  
        <example>
          LogFormat "%h %l %u %t \"%r\" %&gt;s %b \"%{Referer}i\"
          \"%{User-agent}i\"" combined<br />
           CustomLog log/acces_log combined
        </example>
  
        <p>This format is exactly the same as the Common Log Format,
        with the addition of two more fields. Each of the additional
        fields uses the percent-directive
        <code>%{<em>header</em>}i</code>, where <em>header</em> can be
        any HTTP request header. The access log under this format will
        look like:</p>
        
        <example>
          127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET
          /apache_pb.gif HTTP/1.0" 200 2326
          "http://www.example.com/start.html" "Mozilla/4.08 [en]
          (Win98; I ;Nav)"
        </example>
  
        <p>The additional fields are:</p>
        
        <dl>
          <dt><code>"http://www.example.com/start.html"</code>
          (<code>\"%{Referer}i\"</code>)</dt>
  
          <dd>The "Referer" (sic) HTTP request header. This gives the
          site that the client reports having been referred from. (This
          should be the page that links to or includes
          <code>/apache_pb.gif</code>).</dd>
  
          <dt><code>"Mozilla/4.08 [en] (Win98; I ;Nav)"</code>
          (<code>\"%{User-agent}i\"</code>)</dt>
  
          <dd>The User-Agent HTTP request header. This is the
          identifying information that the client browser reports about
          itself.</dd>
        </dl>
      </section>
      
      <section id="multiple">
        <title>Multiple Access Logs</title>
        
        <p>Multiple access logs can be created simply by specifying
        multiple <directive module="core">CustomLog</directive> 
        directives in the configuration
        file. For example, the following directives will create three
        access logs. The first contains the basic CLF information,
        while the second and third contain referer and browser
        information. The last two <directive module="core">
        CustomLog</directive> lines show how
        to mimic the effects of the <directive module="core">ReferLog</directive> 
        and <directive module="core">AgentLog</directive> directives.</p>
  
        <example>
          LogFormat "%h %l %u %t \"%r\" %&gt;s %b" common<br />
          CustomLog logs/access_log common<br />
          CustomLog logs/referer_log "%{Referer}i -&gt; %U"<br />
          CustomLog logs/agent_log "%{User-agent}i"
        </example>
  
        <p>This example also shows that it is not necessary to define a
        nickname with the <code>LogFormat</code> directive. Instead,
        the log format can be specified directly in the 
        <directive module="core">CustomLog</directive> directive.</p>
      </section>
      
      <section id="conditional">
        <title>Conditional Logs</title>
        
        <p>There are times when it is convenient to exclude certain
        entries from the access logs based on characteristics of the
        client request. This is easily accomplished with the help of <a
        href="env.html">environment variables</a>. First, an
        environment variable must be set to indicate that the request
        meets certain conditions. This is usually accomplished with 
        <directive module="mod_setenvif">SetEnvIf</directive>. Then the
        <code>env=</code> clause of the <code>CustomLog</code>
        directive is used to include or exclude requests where the
        environment variable is set. Some examples:</p>
  
        <example>
          # Mark requests from the loop-back interface<br />
          SetEnvIf Remote_Addr "127\.0\.0\.1" dontlog<br />
          # Mark requests for the robots.txt file<br />
          SetEnvIf Request_URI "^/robots\.txt$" dontlog<br />
          # Log what remains<br />
          CustomLog logs/access_log common env=!dontlog
        </example>
  
        <p>As another example, consider logging requests from
        english-speakers to one log file, and non-english speakers to a
        different log file.</p>
  
        <example>
          SetEnvIf Accept-Language "en" english<br />
          CustomLog logs/english_log common env=english<br />
          CustomLog logs/non_english_log common env=!english
        </example>
  
        <p>Although we have just shown that conditional logging is very
        powerful and flexibly, it is not the only way to control the
        contents of the logs. Log files are more useful when they
        contain a complete record of server activity. It is often
        easier to simply post-process the log files to remove requests
        that you do not want to consider.</p>
      </section>
    </section>
    
    <section id="rotation">
      <title>Rotation Logs</title>
      
      <p>On even a moderately busy server, the quantity of
      information stored in the log files is very large. The access
      log file typically grows 1 MB or more per 10,000 requests. It
      will consequently be necessary to periodically rotate the log
      files by moving or deleting the existing logs. This cannot be
      done while the server is running, because Apache will continue
      writing to the old log file as long as it holds the file open.
      Instead, the server must be <a
      href="stopping.html">restarted</a> after the log files are
      moved or deleted so that it will open new log files.</p>
  
      <p>By using a <em>graceful</em> restart, the server can be
      instructed to open new log files without losing any existing or
      pending connections from clients. However, in order to
      accomplish this, the server must continue to write to the old
      log files while it finishes serving old requests. It is
      therefore necessary to wait for some time after the restart
      before doing any processing on the log files. A typical
      scenario that simply rotates the logs and compresses the old
      logs to save space is:</p>
  
      <example>
        mv access_log access_log.old<br />
        mv error_log error_log.old<br />
        apachectl graceful<br />
        sleep 600<br />
        gzip access_log.old error_log.old
      </example>
  
      <p>Another way to perform log rotation is using <a
      href="#piped">piped logs</a> as discussed in the next
      section.</p>
    </section>
    
    <section id="piped">
      <title>Piped Logs</title>
      
      <p>Apache httpd is capable of writing error and access log
      files through a pipe to another process, rather than directly
      to a file. This capability dramatically increases the
      flexibility of logging, without adding code to the main server.
      In order to write logs to a pipe, simply replace the filename
      with the pipe character "<code>|</code>", followed by the name
      of the executable which should accept log entries on its
      standard input. Apache will start the piped-log process when
      the server starts, and will restart it if it crashes while the
      server is running. (This last feature is why we can refer to
      this technique as "reliable piped logging".)</p>
  
      <p>Piped log processes are spawned by the parent Apache httpd
      process, and inherit the userid of that process. This means
      that piped log programs usually run as root. It is therefore
      very important to keep the programs simple and secure.</p>
  
      <p>Some simple examples using piped logs:</p>
  
      <example>
        # compressed logs<br />
        CustomLog "|/usr/bin/gzip -c &gt;&gt;
        /var/log/access_log.gz" common<br />
        # almost-real-time name resolution<br />
        CustomLog "|/usr/local/apache/bin/logresolve &gt;&gt;
        /var/log/access_log" common
      </example>
  
      <p>Notice that quotes are used to enclose the entire command
      that will be called for the pipe. Although these examples are
      for the access log, the same technique can be used for the
      error log.</p>
  
      <p>One important use of piped logs is to allow log rotation
      without having to restart the server. The Apache HTTP Server
      includes a simple program called <a
      href="programs/rotatelogs.html">rotatelogs</a> for this
      purpose. For example, to rotate the logs every 24 hours, you
      can use:</p>
  
      <example>
        CustomLog "|/usr/local/apache/bin/rotatelogs
        /var/log/access_log 86400" common
      </example>
      
      <p>A similar, but much more flexible log rotation program
      called <a href="http://www.cronolog.org/">cronolog</a>
      is available at an external site.</p>
  
      <p>As with conditional logging, piped logs are a very powerful
      tool, but they should not be used where a simpler solution like
      off-line post-processing is available.</p>
    </section>
    
    <section id="virtualhost">
      <title>Virtual Hosts</title>
      
      <p>When running a server with many <a href="vhosts/">virtual
      hosts</a>, there are several options for dealing with log
      files. First, it is possible to use logs exactly as in a
      single-host server. Simply by placing the logging directives
      outside the <code>&lt;VirtualHost&gt;</code> sections in the
      main server context, it is possible to log all requests in the
      same access log and error log. This technique does not allow
      for easy collection of statistics on individual virtual
      hosts.</p>
  
      <p>If <directive module="mod_log_config">CustomLog</directive> 
      or <directive module="mod_log_config">ErrorLog</directive>
      directives are placed inside a <directive module="core">
      &lt;VirtualHost&gt;</directive>
      section, all requests or errors for that virtual host will be
      logged only to the specified file. Any virtual host which does
      not have logging directives will still have its requests sent
      to the main server logs. This technique is very useful for a
      small number of virtual hosts, but if the number of hosts is
      very large, it can be complicated to manage. In addition, it
      can often create problems with <a
      href="vhosts/fd-limits.html">insufficient file
      descriptors</a>.</p>
  
      <p>For the access log, there is a very good compromise. By
      adding information on the virtual host to the log format
      string, it is possible to log all hosts to the same log, and
      later split the log into individual files. For example,
      consider the following directives.</p>
  
      <example>
        LogFormat "%v %l %u %t \"%r\" %&gt;s %b"
        comonvhost<br />
        CustomLog logs/access_log comonvhost
      </example>
  
      <p>The <code>%v</code> is used to log the name of the virtual
      host that is serving the request. Then a program like <a
      href="programs/other.html">split-logfile</a> can be used to
      post-process the access log in order to split it into one file
      per virtual host.</p>
    </section>
    
    <section id="other">
      <title>Other Log Files</title>
      
      <related>
        <modulelist>
          <module>mod_cgi</module>
          <module>mod_rewrite</module>
        </modulelist>
        <directivelist>
          <directive module="core">PidFile</directive>
          <directive module="mod_rewrite">RewriteLog</directive>
          <directive module="mod_rewrite">RewriteLogLevel</directive>
          <directive module="mod_cgi">ScriptLog</directive>
          <directive module="mod_cgi">ScriptLogLength</directive>
          <directive module="mod_cgi">ScriptBuffer</directive>
        </directivelist>
      </related>
      
      <section id="pidfile">
        <title>PID File</title>
      
        <p>On startup, Apache httpd saves the process id of the parent
        httpd process to the file <code>logs/httpd.pid</code>. This
        filename can be changed with the <directive module="core">PidFile
        </directive> directive. The
        process-id is for use by the administrator in restarting and
        terminating the daemon by sending signals to the parent
        process; on Windows, use the -k command line option instead.
        For more information see the <a href="stopping.html">Stopping
        and Restarting</a> page.</p>    
      </section>
      
      <section id="scriptlog">
        <title>Script Log</title>
        
        <p>In order to aid in debugging, the <directive module="mod_cgi">
        ScriptLog</directive> directive
        allows you to record the input to and output from CGI scripts.
        This should only be used in testing - not for live servers.
        More information is available in the <a
        href="mod/mod_cgi.html">mod_cgi documentation</a>.</p>
      </section>
      
      <section id="rewritelog">
        <title>Rewrite Log</title>
        
        <p>When using the powerful and complex features of <a
        href="mod/mod_rewrite.html">mod_rewrite</a>, it is almost
        always necessary to use the <directive module="mod_rewrite">
        RewriteLog</directive> to help
        in debugging. This log file produces a detailed analysis of how
        the rewriting engine transforms requests. The level of detail
        is controlled by the <directive module="mod_rewrite">
        RewriteLogLevel</directive> directive.</p>
      </section>
    </section>
  </manualpage>
  
  
  
  
  
  
  

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