APACHE_1_3_42/htdocs/manual/mod/mod_log_config.html.en - httpd - Git at Google

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     <h1 align="CENTER">Module mod_log_config</h1>

     <p>This module provides for logging of the requests made to the
     server, using the Common Log Format or a user-specified
     format.</p>

     <p><a href="module-dict.html#Status"
     rel="Help"><strong>Status:</strong></a> Base<br />
      <a href="module-dict.html#SourceFile"
     rel="Help"><strong>Source File:</strong></a>
     mod_log_config.c<br />
      <a href="module-dict.html#ModuleIdentifier"
     rel="Help"><strong>Module Identifier:</strong></a>
     config_log_module<br />
      <a href="module-dict.html#Compatibility"
     rel="Help"><strong>Compatibility:</strong></a> Was an extension
     module prior to Apache 1.2.</p>

     <h2>Summary</h2>

     <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>TransferLog</code> to create a log file,
     <code>LogFormat</code> to set a custom format, and
     <code>CustomLog</code> to define a log file and format in one
     step. The <code>TransferLog</code> and <code>CustomLog</code>
     directives can be used multiple times in each server to cause
     each request to be logged to multiple files.</p>

     <p>See also: <a href="../logs.html">Apache Log Files</a>.</p>

     <h2>Directives</h2>

     <ul>
       <li><a href="#cookielog">CookieLog</a></li>

       <li><a href="#customlog">CustomLog</a></li>

       <li><a href="#logformat">LogFormat</a></li>

       <li><a href="#transferlog">TransferLog</a></li>
     </ul>

     <h2><a id="formats" name="formats">Custom Log Formats</a></h2>

     <p>The format argument to the <code>LogFormat</code> and
     <code>CustomLog</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 back-slashes should be escaped with
     back-slashes.</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 entry by the values as follows:</p>
 <pre>
 %...a:          Remote IP-address
 %...A:          Local IP-address
 %...B:          Bytes sent, excluding HTTP headers.
 %...b:          Bytes sent, excluding HTTP headers. In CLF format
         i.e. a '-' rather than a 0 when no bytes are sent.
 %...c:          Connection status when response was completed.
                 'X' = connection aborted before the response completed.
                 '+' = connection may be kept alive after the response is sent.
                 '-' = connection will be closed after the response is sent.
 %...{FOOBAR}e:  The contents of the environment variable FOOBAR
 %...f:          Filename
 %...h:          Remote host
 %...H       The request protocol
 %...{Foobar}i:  The contents of Foobar: header line(s) in the request
                 sent to the server.
 %...l:          Remote logname (from identd, if supplied)
 %...m       The request method
 %...{Foobar}n:  The contents of note "Foobar" from another module.
 %...{Foobar}o:  The contents of Foobar: header line(s) in the reply.
 %...p:          The canonical Port of the server serving the request
 %...P:          The process ID of the child that serviced the request.
 %...q       The query string (prepended with a ? if a query string exists,
         otherwise an empty string)
 %...r:          First line of request
 %...s:          Status.  For requests that got internally redirected, this is
                 the status of the *original* request --- %...&gt;s for the last.
 %...t:          Time, in common log format time format (standard english format)
 %...{format}t:  The time, in the form given by format, which should
                 be in strftime(3) format. (potentially localized)
 %...T:          The time taken to serve the request, in seconds.
 %...u:          Remote user (from auth; may be bogus if return status (%s) is 401)
 %...U:          The URL path requested, not including any query string.
 %...v:          The canonical ServerName of the server serving the request.
 %...V:          The server name according to the UseCanonicalName setting.
 </pre>

     <p>The "..." can be nothing at all (<em>e.g.</em>, <code>"%h %u
     %r %s %b"</code>), or it can indicate conditions for inclusion
     of the item (which will cause it to be replaced with "-" if the
     condition is not met). The forms of condition are a list of
     HTTP status codes, which may or may not be preceded by "!".
     Thus, "%400,501{User-agent}i" logs User-agent: on 400 errors
     and 501 errors (Bad Request, Not Implemented) only;
     "%!200,304,302{Referer}i" logs Referer: on all requests which
     did <strong>not</strong> return some sort of normal status.</p>

     <p>Note that in versions previous to 1.3.25 no escaping was performed
     on the strings from <code>%...r</code>, <code>%...i</code> and
     <code>%...o</code>. This was mainly to comply with the requirements of
     the Common Log Format. This implied that clients could insert control
     characters into the log, so you had to be quite careful when dealing
     with raw log files.</p>

     <p>For security reasons starting with 1.3.25 non-printable and
     other special characters are escaped mostly by 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 that are written in their
     C-style notation (<code>\n</code>, <code>\t</code>, etc).</p>

     <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>Note that the canonical <a
     href="core.html#servername">ServerName</a> and <a
     href="core.html#port">Port</a> of the server serving the
     request are used for <code>%v</code> and <code>%p</code>
     respectively. This happens regardless of the <a
     href="core.html#usecanonicalname">UseCanonicalName</a> setting
     because otherwise log analysis programs would have to duplicate
     the entire vhost matching algorithm in order to decide what
     host really served the request.</p>

     <h2>Security Considerations</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>

     <h2>Compatibility notes</h2>

     <ul>
       <li>This module is based on mod_log_config distributed with
       previous Apache releases, now updated to handle multiple
       logs. There is now no need to rebuild Apache to change
       configuration log formats.</li>

       <li>The module also implements the <code>CookieLog</code>
       directive, used to log user-tracking information created by
       <a href="mod_usertrack.html">mod_usertrack</a>. The use of
       <code>CookieLog</code> is deprecated, and a
       <code>CustomLog</code> should be defined to log user-tracking
       information instead.</li>

       <li>As of Apache 1.3.5, this module allows conditional
       logging based upon the setting of <a
       href="../env.html">environment variables</a>. That is, you
       can control whether a request should be logged or not based
       upon whether an arbitrary environment variable is defined or
       not. This is configurable on a per-logfile
       basis.</li>

       <li>Beginning with Apache 1.3.5, the mod_log_config module
       has also subsumed the <code>RefererIgnore</code>
       functionality from <a
       href="mod_log_referer.html">mod_log_referer</a>. The effect
       of <code>RefererIgnore</code> can be achieved by combinations
       of <a href="mod_setenvif.html"><code>SetEnvIf</code></a>
       directives and conditional <code>CustomLog</code>
       definitions.</li>
     </ul>
     <hr />

     <h2><a id="cookielog" name="cookielog">CookieLog</a>
     directive</h2>

     <p><a href="directive-dict.html#Syntax"
     rel="Help"><strong>Syntax:</strong></a> CookieLog
     <em>filename</em><br />
      <a href="directive-dict.html#Context"
     rel="Help"><strong>Context:</strong></a> server config, virtual
     host<br />
      <a href="directive-dict.html#Module"
     rel="Help"><strong>Module:</strong></a> mod_cookies<br />
      <a href="directive-dict.html#Compatibility"
     rel="Help"><strong>Compatibility:</strong></a> Only available
     in Apache 1.2 and above</p>

     <p>The CookieLog directive sets the filename for logging of
     cookies. The filename is relative to the <a
     href="core.html#serverroot">ServerRoot</a>. This directive is
     included only for compatibility with <a
     href="mod_cookies.html">mod_cookies</a>, and is deprecated.</p>
     <hr />

     <h2><a id="customlog" name="customlog">CustomLog</a> <a
     id="customlog-conditional"
     name="customlog-conditional">directive</a></h2>

     <p><a href="directive-dict.html#Syntax"
     rel="Help"><strong>Syntax:</strong></a> CustomLog
     <em>file</em>|<em>pipe</em> <em>format</em>|<em>nickname</em>
     [env=[!]<em>environment-variable</em>]<br />
      <a href="directive-dict.html#Context"
     rel="Help"><strong>Context:</strong></a> server config, virtual
     host<br />
      <a href="directive-dict.html#Status"
     rel="Help"><strong>Status:</strong></a> Base<br />
      <a href="directive-dict.html#Compatibility"
     rel="Help"><strong>Compatibility:</strong></a> Nickname only
     available in Apache 1.3 or later. Conditional logging available
     in 1.3.5 or later.<br />
      <a href="directive-dict.html#Module"
     rel="Help"><strong>Module:</strong></a> mod_log_config</p>

     <p>The <code>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><em>file</em></dt>

       <dd>A filename, relative to the <a
       href="core.html#serverroot">ServerRoot</a>.</dd>

       <dt><em>pipe</em></dt>

       <dd>The pipe character "<code>|</code>", followed by the path
       to a program to receive the log information on its standard
       input. <strong>Security:</strong> if a program is used, then
       it will be run as the user who started httpd. This will be
       root if the server was started by root; be sure that the
       program is secure.</dd>
     </dl>

     <p>The second argument specifies what will be written to the
     log file. It can specify either a <em>nickname</em> defined by
     a previous <a href="#logformat">LogFormat</a> directive, or it
     can be an explicit <em>format</em> 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>
      # 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 based on the
     presence or absence of a particular variable in the server
     environment. If the specified <a href="../env.html">environment
     variable</a> is set for the request (or is not set, in the case
     of a '<code>env=!<em>name</em></code>' clause), then the
     request will be logged.</p>

     <p>Environment variables can be set on a per-request
     basis using the <a href="mod_setenvif.html">mod_setenvif</a>
     and/or <a href="mod_rewrite.html">mod_rewrite</a> 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>
     SetEnvIf Request_URI \.gif$ gif-image
     CustomLog gif-requests.log common env=gif-image
     CustomLog nongif-requests.log common env=!gif-image
 </pre>
     <hr />

     <h2><a id="logformat" name="logformat">LogFormat</a>
     directive</h2>

     <p><a href="directive-dict.html#Syntax"
     rel="Help"><strong>Syntax:</strong></a> LogFormat
     <em>format</em>|<em>nickname</em> [<em>nickname</em>]<br />
      <a href="directive-dict.html#Default"
     rel="Help"><strong>Default:</strong></a> <code>LogFormat "%h %l
     %u %t \"%r\" %&gt;s %b"</code><br />
      <a href="directive-dict.html#Context"
     rel="Help"><strong>Context:</strong></a> server config, virtual
     host<br />
      <a href="directive-dict.html#Status"
     rel="Help"><strong>Status:</strong></a> Base<br />
      <a href="directive-dict.html#Compatibility"
     rel="Help"><strong>Compatibility:</strong></a> Nickname only
     available in Apache 1.3 or later<br />
      <a href="directive-dict.html#Module"
     rel="Help"><strong>Module:</strong></a> mod_log_config</p>

     <p>This directive specifies the format of the access log
     file.</p>

     <p>The <code>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 <a href="#transferlog">TransferLog</a>
     directives. The single argument can specify an explicit
     <em>format</em> as discussed in the <a href="#formats">custom log
     formats</a> section above. Alternatively, it can use a
     <em>nickname</em> to refer to a log format defined in a
     previous <code>LogFormat</code> directive as described
     below.</p>

     <p>The second form of the <code>LogFormat</code> directive
     associates an explicit <em>format</em> with a
     <em>nickname</em>. This <em>nickname</em> can then be used in
     subsequent <code>LogFormat</code> or <a
     href="#customlog">CustomLog</a> directives rather than
     repeating the entire format string. A <samp>LogFormat</samp>
     directive which 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 <a
     href="#transferlog">TransferLog</a> directives.</p>

     <p>For example:</p>

     <code>LogFormat "%v %h %l %u %t \"%r\" %&gt;s %b" vhost_common</code>

     <hr />

     <h2><a id="transferlog" name="transferlog">TransferLog</a>
     directive</h2>

     <p><a href="directive-dict.html#Syntax"
     rel="Help"><strong>Syntax:</strong></a> TransferLog
     <em>file</em>|<em>pipe</em><br />
      <a href="directive-dict.html#Default"
     rel="Help"><strong>Default:</strong></a> none<br />
      <a href="directive-dict.html#Context"
     rel="Help"><strong>Context:</strong></a> server config, virtual
     host<br />
      <a href="directive-dict.html#Status"
     rel="Help"><strong>Status:</strong></a> Base<br />
      <a href="directive-dict.html#Module"
     rel="Help"><strong>Module:</strong></a> mod_log_config</p>

     <p>This directive has exactly the same arguments and effect as
     the <a href="#customlog">CustomLog</a> 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 <a
     href="#logformat">LogFormat</a> directive that does not define
     a nickname. Common Log Format is used if no other format has
     been specified.</p>

     <p>Example:</p>
 <pre>
    LogFormat "%h %l %u %t \"%r\" %&gt;s %b \"%{Referer}i\" \"%{User-agent}i\""
    TransferLog logs/access_log
 </pre>
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	<h1 align="CENTER">Module mod_log_config</h1>

	<p>This module provides for logging of the requests made to the
	server, using the Common Log Format or a user-specified
	format.</p>

	<p><a href="module-dict.html#Status"
	rel="Help"><strong>Status:</strong></a> Base<br />
	<a href="module-dict.html#SourceFile"
	rel="Help"><strong>Source File:</strong></a>
	mod_log_config.c<br />
	<a href="module-dict.html#ModuleIdentifier"
	rel="Help"><strong>Module Identifier:</strong></a>
	config_log_module<br />
	<a href="module-dict.html#Compatibility"
	rel="Help"><strong>Compatibility:</strong></a> Was an extension
	module prior to Apache 1.2.</p>

	<h2>Summary</h2>

	<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>TransferLog</code> to create a log file,
	<code>LogFormat</code> to set a custom format, and
	<code>CustomLog</code> to define a log file and format in one
	step. The <code>TransferLog</code> and <code>CustomLog</code>
	directives can be used multiple times in each server to cause
	each request to be logged to multiple files.</p>

	<p>See also: <a href="../logs.html">Apache Log Files</a>.</p>

	<h2>Directives</h2>

	<ul>
	<li><a href="#cookielog">CookieLog</a></li>

	<li><a href="#customlog">CustomLog</a></li>

	<li><a href="#logformat">LogFormat</a></li>

	<li><a href="#transferlog">TransferLog</a></li>
	</ul>

	<h2><a id="formats" name="formats">Custom Log Formats</a></h2>

	<p>The format argument to the <code>LogFormat</code> and
	<code>CustomLog</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 back-slashes should be escaped with
	back-slashes.</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 entry by the values as follows:</p>
	<pre>
	%...a: Remote IP-address
	%...A: Local IP-address
	%...B: Bytes sent, excluding HTTP headers.
	%...b: Bytes sent, excluding HTTP headers. In CLF format
	i.e. a '-' rather than a 0 when no bytes are sent.
	%...c: Connection status when response was completed.
	'X' = connection aborted before the response completed.
	'+' = connection may be kept alive after the response is sent.
	'-' = connection will be closed after the response is sent.
	%...{FOOBAR}e: The contents of the environment variable FOOBAR
	%...f: Filename
	%...h: Remote host
	%...H The request protocol
	%...{Foobar}i: The contents of Foobar: header line(s) in the request
	sent to the server.
	%...l: Remote logname (from identd, if supplied)
	%...m The request method
	%...{Foobar}n: The contents of note "Foobar" from another module.
	%...{Foobar}o: The contents of Foobar: header line(s) in the reply.
	%...p: The canonical Port of the server serving the request
	%...P: The process ID of the child that serviced the request.
	%...q The query string (prepended with a ? if a query string exists,
	otherwise an empty string)
	%...r: First line of request
	%...s: Status. For requests that got internally redirected, this is
	the status of the original request --- %...>s for the last.
	%...t: Time, in common log format time format (standard english format)
	%...{format}t: The time, in the form given by format, which should
	be in strftime(3) format. (potentially localized)
	%...T: The time taken to serve the request, in seconds.
	%...u: Remote user (from auth; may be bogus if return status (%s) is 401)
	%...U: The URL path requested, not including any query string.
	%...v: The canonical ServerName of the server serving the request.
	%...V: The server name according to the UseCanonicalName setting.
	</pre>

	<p>The "..." can be nothing at all (<em>e.g.</em>, <code>"%h %u
	%r %s %b"</code>), or it can indicate conditions for inclusion
	of the item (which will cause it to be replaced with "-" if the
	condition is not met). The forms of condition are a list of
	HTTP status codes, which may or may not be preceded by "!".
	Thus, "%400,501{User-agent}i" logs User-agent: on 400 errors
	and 501 errors (Bad Request, Not Implemented) only;
	"%!200,304,302{Referer}i" logs Referer: on all requests which
	did <strong>not</strong> return some sort of normal status.</p>

	<p>Note that in versions previous to 1.3.25 no escaping was performed
	on the strings from <code>%...r</code>, <code>%...i</code> and
	<code>%...o</code>. This was mainly to comply with the requirements of
	the Common Log Format. This implied that clients could insert control
	characters into the log, so you had to be quite careful when dealing
	with raw log files.</p>

	<p>For security reasons starting with 1.3.25 non-printable and
	other special characters are escaped mostly by 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 that are written in their
	C-style notation (<code>\n</code>, <code>\t</code>, etc).</p>

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

	<dl>
	<dt>Common Log Format (CLF)</dt>

	<dd><code>"%h %l %u %t \"%r\" %>s %b"</code></dd>

	<dt>Common Log Format with Virtual Host</dt>

	<dd><code>"%v %h %l %u %t \"%r\" %>s %b"</code></dd>

	<dt>NCSA extended/combined log format</dt>

	<dd><code>"%h %l %u %t \"%r\" %>s %b \"%{Referer}i\"
	\"%{User-agent}i\""</code></dd>

	<dt>Referer log format</dt>

	<dd><code>"%{Referer}i -> %U"</code></dd>

	<dt>Agent (Browser) log format</dt>

	<dd><code>"%{User-agent}i"</code></dd>
	</dl>

	<p>Note that the canonical <a
	href="core.html#servername">ServerName</a> and <a
	href="core.html#port">Port</a> of the server serving the
	request are used for <code>%v</code> and <code>%p</code>
	respectively. This happens regardless of the <a
	href="core.html#usecanonicalname">UseCanonicalName</a> setting
	because otherwise log analysis programs would have to duplicate
	the entire vhost matching algorithm in order to decide what
	host really served the request.</p>

	<h2>Security Considerations</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>

	<h2>Compatibility notes</h2>

	<ul>
	<li>This module is based on mod_log_config distributed with
	previous Apache releases, now updated to handle multiple
	logs. There is now no need to rebuild Apache to change
	configuration log formats.</li>

	<li>The module also implements the <code>CookieLog</code>
	directive, used to log user-tracking information created by
	<a href="mod_usertrack.html">mod_usertrack</a>. The use of
	<code>CookieLog</code> is deprecated, and a
	<code>CustomLog</code> should be defined to log user-tracking
	information instead.</li>

	<li>As of Apache 1.3.5, this module allows conditional
	logging based upon the setting of <a
	href="../env.html">environment variables</a>. That is, you
	can control whether a request should be logged or not based
	upon whether an arbitrary environment variable is defined or
	not. This is configurable on a per-logfile
	basis.</li>

	<li>Beginning with Apache 1.3.5, the mod_log_config module
	has also subsumed the <code>RefererIgnore</code>
	functionality from <a
	href="mod_log_referer.html">mod_log_referer</a>. The effect
	of <code>RefererIgnore</code> can be achieved by combinations
	of <a href="mod_setenvif.html"><code>SetEnvIf</code></a>
	directives and conditional <code>CustomLog</code>
	definitions.</li>
	</ul>
	<hr />

	<h2><a id="cookielog" name="cookielog">CookieLog</a>
	directive</h2>

	<p><a href="directive-dict.html#Syntax"
	rel="Help"><strong>Syntax:</strong></a> CookieLog
	<em>filename</em><br />
	<a href="directive-dict.html#Context"
	rel="Help"><strong>Context:</strong></a> server config, virtual
	host<br />
	<a href="directive-dict.html#Module"
	rel="Help"><strong>Module:</strong></a> mod_cookies<br />
	<a href="directive-dict.html#Compatibility"
	rel="Help"><strong>Compatibility:</strong></a> Only available
	in Apache 1.2 and above</p>

	<p>The CookieLog directive sets the filename for logging of
	cookies. The filename is relative to the <a
	href="core.html#serverroot">ServerRoot</a>. This directive is
	included only for compatibility with <a
	href="mod_cookies.html">mod_cookies</a>, and is deprecated.</p>
	<hr />

	<h2><a id="customlog" name="customlog">CustomLog</a> <a
	id="customlog-conditional"
	name="customlog-conditional">directive</a></h2>

	<p><a href="directive-dict.html#Syntax"
	rel="Help"><strong>Syntax:</strong></a> CustomLog
	<em>file</em>\|<em>pipe</em> <em>format</em>\|<em>nickname</em>
	[env=[!]<em>environment-variable</em>]<br />
	<a href="directive-dict.html#Context"
	rel="Help"><strong>Context:</strong></a> server config, virtual
	host<br />
	<a href="directive-dict.html#Status"
	rel="Help"><strong>Status:</strong></a> Base<br />
	<a href="directive-dict.html#Compatibility"
	rel="Help"><strong>Compatibility:</strong></a> Nickname only
	available in Apache 1.3 or later. Conditional logging available
	in 1.3.5 or later.<br />
	<a href="directive-dict.html#Module"
	rel="Help"><strong>Module:</strong></a> mod_log_config</p>

	<p>The <code>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><em>file</em></dt>

	<dd>A filename, relative to the <a
	href="core.html#serverroot">ServerRoot</a>.</dd>

	<dt><em>pipe</em></dt>

	<dd>The pipe character "<code>\|</code>", followed by the path
	to a program to receive the log information on its standard
	input. <strong>Security:</strong> if a program is used, then
	it will be run as the user who started httpd. This will be
	root if the server was started by root; be sure that the
	program is secure.</dd>
	</dl>

	<p>The second argument specifies what will be written to the
	log file. It can specify either a <em>nickname</em> defined by
	a previous <a href="#logformat">LogFormat</a> directive, or it
	can be an explicit <em>format</em> 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>
	# CustomLog with format nickname
	LogFormat "%h %l %u %t \"%r\" %>s %b" common
	CustomLog logs/access_log common

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

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

	<p>Environment variables can be set on a per-request
	basis using the <a href="mod_setenvif.html">mod_setenvif</a>
	and/or <a href="mod_rewrite.html">mod_rewrite</a> 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>
	SetEnvIf Request_URI \.gif$ gif-image
	CustomLog gif-requests.log common env=gif-image
	CustomLog nongif-requests.log common env=!gif-image
	</pre>
	<hr />

	<h2><a id="logformat" name="logformat">LogFormat</a>
	directive</h2>

	<p><a href="directive-dict.html#Syntax"
	rel="Help"><strong>Syntax:</strong></a> LogFormat
	<em>format</em>\|<em>nickname</em> [<em>nickname</em>]<br />
	<a href="directive-dict.html#Default"
	rel="Help"><strong>Default:</strong></a> <code>LogFormat "%h %l
	%u %t \"%r\" %>s %b"</code><br />
	<a href="directive-dict.html#Context"
	rel="Help"><strong>Context:</strong></a> server config, virtual
	host<br />
	<a href="directive-dict.html#Status"
	rel="Help"><strong>Status:</strong></a> Base<br />
	<a href="directive-dict.html#Compatibility"
	rel="Help"><strong>Compatibility:</strong></a> Nickname only
	available in Apache 1.3 or later<br />
	<a href="directive-dict.html#Module"
	rel="Help"><strong>Module:</strong></a> mod_log_config</p>

	<p>This directive specifies the format of the access log
	file.</p>

	<p>The <code>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 <a href="#transferlog">TransferLog</a>
	directives. The single argument can specify an explicit
	<em>format</em> as discussed in the <a href="#formats">custom log
	formats</a> section above. Alternatively, it can use a
	<em>nickname</em> to refer to a log format defined in a
	previous <code>LogFormat</code> directive as described
	below.</p>

	<p>The second form of the <code>LogFormat</code> directive
	associates an explicit <em>format</em> with a
	<em>nickname</em>. This <em>nickname</em> can then be used in
	subsequent <code>LogFormat</code> or <a
	href="#customlog">CustomLog</a> directives rather than
	repeating the entire format string. A <samp>LogFormat</samp>
	directive which 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 <a
	href="#transferlog">TransferLog</a> directives.</p>

	<p>For example:</p>

	<code>LogFormat "%v %h %l %u %t \"%r\" %>s %b" vhost_common</code>

	<hr />

	<h2><a id="transferlog" name="transferlog">TransferLog</a>
	directive</h2>

	<p><a href="directive-dict.html#Syntax"
	rel="Help"><strong>Syntax:</strong></a> TransferLog
	<em>file</em>\|<em>pipe</em><br />
	<a href="directive-dict.html#Default"
	rel="Help"><strong>Default:</strong></a> none<br />
	<a href="directive-dict.html#Context"
	rel="Help"><strong>Context:</strong></a> server config, virtual
	host<br />
	<a href="directive-dict.html#Status"
	rel="Help"><strong>Status:</strong></a> Base<br />
	<a href="directive-dict.html#Module"
	rel="Help"><strong>Module:</strong></a> mod_log_config</p>

	<p>This directive has exactly the same arguments and effect as
	the <a href="#customlog">CustomLog</a> 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 <a
	href="#logformat">LogFormat</a> directive that does not define
	a nickname. Common Log Format is used if no other format has
	been specified.</p>

	<p>Example:</p>
	<pre>
	LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\""
	TransferLog logs/access_log
	</pre>
	<!--#include virtual="footer.html" -->
	</body>
	</html>