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<html xmlns="http://www.w3.org/TR/xhtml1/strict"><head><!--
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--><title>mod_log_config - Apache HTTP Server</title><link href="../style/manual.css" type="text/css" rel="stylesheet"/></head><body><blockquote><div align="center"><img alt="[APACHE DOCUMENTATION]" src="../images/sub.gif"/><h3>Apache HTTP Server Version 2.0</h3></div><h1 align="center">Apache Module mod_log_config</h1><table cellspacing="1" cellpadding="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td valign="top"><span class="help">Description:</span></td><td>Logging of the requests made to the server</td></tr><tr><td><a href="module-dict.html#Status" class="help">Status:</a></td><td>Base</td></tr><tr><td><a href="module-dict.html#ModuleIdentifier" class="help">Module Identifier:</a></td><td>log_config_module</td></tr></table></td></tr></table><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>
<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><p><strong>See also </strong></p><ul><li><a href="../logs.html">Apache Log Files</a></li></ul><h2><a 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
logged to the log file for each request. It can contain literal
characters copied into the log files and the c-type 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 "%" directives in the format string, which are replaced
in the log file by the values as follows:</p>
<table>
<tr><td>%...a:</td>
<td>Remote IP-address</td></tr>
<tr><td>%...A:</td>
<td>Local IP-address</td></tr>
<tr><td>%...B:</td>
<td>Bytes sent, excluding HTTP headers.</td></tr>
<tr><td>%...b:</td>
<td>Bytes sent, excluding HTTP headers. In CLF format
i.e. a '-' rather than a 0 when no bytes are sent.</td></tr>
<tr><td>%...{Foobar}C:</td>
<td>The contents of cookie "Foobar" in the request sent to the server.</td></tr>
<tr><td>%...D:</td>
<td>The time taken to serve the request, in microseconds.</td></tr>
<tr><td>%...{FOOBAR}e:</td>
<td>The contents of the environment variable FOOBAR</td></tr>
<tr><td>%...f:</td>
<td>Filename</td></tr>
<tr><td>%...h:</td>
<td>Remote host</td></tr>
<tr><td>%...H</td>
<td>The request protocol</td></tr>
<tr><td>%...{Foobar}i:</td>
<td>The contents of Foobar: header line(s) in the request
sent to the server.</td></tr>
<tr><td>%...l:</td>
<td>Remote logname (from identd, if supplied)</td></tr>
<tr><td>%...m:</td>
<td>The request method</td></tr>
<tr><td>%...{Foobar}n:</td>
<td>The contents of note "Foobar" from another module.</td></tr>
<tr><td>%...{Foobar}o:</td>
<td>The contents of Foobar: header line(s) in the reply.</td></tr>
<tr><td>%...p:</td>
<td>The canonical Port of the server serving the request</td></tr>
<tr><td>%...P:</td>
<td>The process ID of the child that serviced the request.</td></tr>
<tr><td>%...q:</td>
<td>The query string (prepended with a ? if a query string exists,
otherwise an empty string)</td></tr>
<tr><td>%...r:</td>
<td>First line of request</td></tr>
<tr><td>%...s:</td>
<td>Status. For requests that got internally redirected, this is
the status of the *original* request --- %...>s for the last.</td></tr>
<tr><td>%...t:</td>
<td>Time, in common log format time format (standard english format)</td></tr>
<tr><td>%...{format}t:</td>
<td>The time, in the form given by format, which should
be in strftime(3) format. (potentially localized)</td></tr>
<tr><td>%...T:</td>
<td>The time taken to serve the request, in seconds.</td></tr>
<tr><td>%...u:</td>
<td>Remote user (from auth; may be bogus if return status (%s) is 401)</td></tr>
<tr><td>%...U:</td>
<td>The URL path requested, not including any query string.</td></tr>
<tr><td>%...v:</td>
<td>The canonical ServerName of the server serving the request.</td></tr>
<tr><td>%...V:</td>
<td>The server name according to the UseCanonicalName setting.</td></tr>
<tr><td>%...X:</td>
<td>Connection status when response is completed.
<blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
'X' = connection aborted before the response completed.<br>
'+' = connection may be kept alive after the response is sent.<br>
'-' = connection will be closed after the response is sent.
</code></td></tr></table></blockquote>
<blockquote><table><tr><td bgcolor="#e0e5f5">(This directive was %...c in late versions of Apache 1.3, but
this conflicted with the historical ssl %...{var}c syntax.)</td></tr></table></blockquote>
</td></tr>
</table>
<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 there is no escaping performed on the strings from
%...r, %...i and %...o. This is mainly to comply with the
requirements of the Common Log Format. This implies that
clients can insert control characters into the log, so care
should be taken when dealing with raw log files.</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="mpm_common.html#listen">Listen</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>
<hr/><h2><a name="CookieLog">CookieLog</a> <a name="cookielog">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td><strong>Description: </strong></td><td>Sets filename for the logging of cookies</td></tr><tr><td><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>CookieLog <em>filename</em></td></tr><tr><td><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config, virtual
host</td></tr><tr><td><a href="directive-dict.html#Status" class="help">Status:</a></td><td>Base</td></tr><tr><td><a href="directive-dict.html#Module" class="help">Module:</a></td><td>mod_log_config</td></tr><tr><td align="left" valign="top"><a href="directive-dict.html#Compatibility" class="help">Compatibility:</a></td><td>Only available in Apache 1.2 and above</td></tr></table></td></tr></table>
<p>The <code class="directive">CookieLog</code> directive sets the
filename for logging of cookies. The filename is relative to the
<a href="core.html#serverroot" class="directive"><code class="directive">serverroot</code></a>. This directive is
included only for compatibility with <code><a href="mod_cookies.html">mod_cookies</a></code>,
and is deprecated.</p>
<hr/><h2><a name="CustomLog">CustomLog</a> <a name="customlog">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td><strong>Description: </strong></td><td>Sets filename and format of log file</td></tr><tr><td><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>CustomLog
<em>file</em>|<em>pipe</em> <em>format</em>|<em>nickname</em>
[env=[!]<em>environment-variable</em>]</td></tr><tr><td><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config, virtual
host</td></tr><tr><td><a href="directive-dict.html#Status" class="help">Status:</a></td><td>Base</td></tr><tr><td><a href="directive-dict.html#Module" class="help">Module:</a></td><td>mod_log_config</td></tr><tr><td align="left" valign="top"><a href="directive-dict.html#Compatibility" class="help">Compatibility:</a></td><td>Nickname only available in Apache 1.3 or later.
Conditional logging available in 1.3.5 or later.</td></tr></table></td></tr></table>
<p>The <code class="directive">CustomLog</code> directive is used to
log requests to the server. A log format is specified, and the
logging can optionally be made conditional on request
characteristics using environment variables.</p>
<p>The first argument, which specifies the location to which
the logs will be written, can take on 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 under 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>
<blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
# CustomLog with format nickname<br>
LogFormat "%h %l %u %t \"%r\" %>s %b" common<br>
CustomLog logs/access_log common<br>
<br>
# CustomLog with explicit format string<br>
CustomLog logs/access_log "%h %l %u %t \"%r\" %>s %b"<br>
</code></td></tr></table></blockquote>
<p>The third argument is optional and allows the decision on
whether or not to log a particular request to be 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 <em>per</em>-request
basis using the <code><a href="mod_setenvif.html">mod_setenvif</a></code>
and/or <code><a href="mod_rewrite.html">mod_rewrite</a></code> modules. For
example, if you don't want to record requests for all GIF
images on your server in a separate logfile but not your main
log, you can use:</p>
<blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
SetEnvIf Request_URI \.gif$ gif-image<br>
CustomLog gif-requests.log common env=gif-image<br>
CustomLog nongif-requests.log common env=!gif-image
</code></td></tr></table></blockquote>
<hr/><h2><a name="LogFormat">LogFormat</a> <a name="logformat">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td><strong>Description: </strong></td><td>Describes a format for use in a log file</td></tr><tr><td><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>LogFormat
<em>format</em>|<em>nickname</em> [<em>nickname</em>]</td></tr><tr><td><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config, virtual
host</td></tr><tr><td><a href="directive-dict.html#Status" class="help">Status:</a></td><td>Base</td></tr><tr><td><a href="directive-dict.html#Module" class="help">Module:</a></td><td>mod_log_config</td></tr><tr><td align="left" valign="top"><a href="directive-dict.html#Compatibility" class="help">Compatibility:</a></td><td>Nickname only available in Apache 1.3 or later.
</td></tr></table></td></tr></table>
<p>This directive specifies the format of the access log
file.</p>
<p>The <code class="directive">LogFormat</code> directive can take one of two
forms. In the first form, where only one argument is specified,
this directive sets the log format which will be used by logs
specified in subsequent <code class="directive">TransferLog</code>
directives. The single argument can specify an explicit
<em>format</em> as discussed in <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 class="directive">LogFormat</code> directive as described
below.</p>
<p>The second form of the <code class="directive">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 class="directive">LogFormat</code> or
<code class="directive">CustomLog</code> directives rather than
repeating the entire format string. A
<code class="directive">LogFormat</code>
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
<code class="directive">TransferLog</code> directives.</p>
<hr/><h2><a name="TransferLog">TransferLog</a> <a name="transferlog">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td><strong>Description: </strong></td><td>Specifly location of a log file</td></tr><tr><td><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>TransferLog <em>file</em>|<em>pipe</em></td></tr><tr><td><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config, virtual
host</td></tr><tr><td><a href="directive-dict.html#Status" class="help">Status:</a></td><td>Base</td></tr><tr><td><a href="directive-dict.html#Module" class="help">Module:</a></td><td>mod_log_config</td></tr><tr><td align="left" valign="top"><a href="directive-dict.html#Compatibility" class="help">Compatibility:</a></td><td/></tr></table></td></tr></table>
<p>This directive has exactly the same arguments and effect as
the <code class="directive">CustomLog</code> directive, with the
exception that it does not allow the log format to be specified
explicitly or for conditional logging of requests. Instead, the
log format is determined by the most recently specified
specified <code class="directive">LogFormat</code> directive (which
does not define a nickname). Common Log Format is used if no
other format has been specified.</p>
<p>Example:</p>
<blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\""<br>
TransferLog logs/access_log
</code></td></tr></table></blockquote>
<hr/><h3 align="center">Apache HTTP Server Version 2.0</h3><a href="./"><img alt="Index" src="../images/index.gif"/></a><a href="../"><img alt="Home" src="../images/home.gif"/></a></blockquote></body></html>
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