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<title>mod_log_debug - Apache HTTP Server Version 2.4</title>
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<div id="preamble"><h1>Apache Module mod_log_debug</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="../en/mod/mod_log_debug.html" title="English"> en </a> |
<a href="../fr/mod/mod_log_debug.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p>
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<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Additional configurable debug logging</td></tr>
<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>log_debug_module</td></tr>
<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_log_debug.c</td></tr>
<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.3.14 and later</td></tr></table>
</div>
<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><h3>Topics</h3>
<ul id="topics">
<li><img alt="" src="../images/down.gif" /> <a href="#examples">Examples</a></li>
</ul><h3 class="directives">Directives</h3>
<ul id="toc">
<li><img alt="" src="../images/down.gif" /> <a href="#logmessage">LogMessage</a></li>
</ul>
<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=mod_log_debug">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=mod_log_debug">Report a bug</a></li></ul><h3>See also</h3>
<ul class="seealso">
<li><a href="#comments_section">Comments</a></li></ul></div>
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<div class="section">
<h2><a name="examples" id="examples">Examples</a></h2>
<ol>
<li>
Log message after request to /foo/* is processed:
<pre class="prettyprint lang-config"><Location "/foo/">
LogMessage "/foo/ has been requested"
</Location></pre>
</li>
<li>
Log message if request to /foo/* is processed in a sub-request:
<pre class="prettyprint lang-config"><Location "/foo/">
LogMessage "subrequest to /foo/" hook=type_checker "expr=-T %{IS_SUBREQ}"
</Location></pre>
The default log_transaction hook is not executed for sub-requests,
therefore we have to use a different hook.
</li>
<li>
Log message if an IPv6 client causes a request timeout:
<pre class="prettyprint lang-config">LogMessage "IPv6 timeout from %{REMOTE_ADDR}" "expr=-T %{IPV6} && %{REQUEST_STATUS} = 408"</pre>
Note the placing of the double quotes for the <code>expr=</code> argument.
</li>
<li>
Log the value of the "X-Foo" request environment variable in each
stage of the request:
<pre class="prettyprint lang-config"><Location "/">
LogMessage "%{reqenv:X-Foo}" hook=all
</Location></pre>
Together with microsecond time stamps in the error log,
<code>hook=all</code> also lets you determine the times spent
in the different parts of the request processing.
</li>
</ol>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="LogMessage" id="LogMessage">LogMessage</a> <a name="logmessage" id="logmessage">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Log user-defined message to error log
</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogMessage <var>message</var>
[hook=<var>hook</var>] [expr=<var>expression</var>]
</code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_log_debug</td></tr>
</table>
<p>This directive causes a user defined message to be logged to the
error log. The message can use variables and functions from the
<a href="../expr.html">ap_expr syntax</a>. References to HTTP headers
will not cause header names to be added to the Vary header. The
messages are logged at loglevel info.</p>
<p>The hook specifies before which phase of request processing the message
will be logged. The following hooks are supported:</p>
<table class="bordered"><tr class="header"><th>Name</th></tr>
<tr><td><code>pre_translate_name</code></td></tr>
<tr class="odd"><td><code>translate_name</code></td></tr>
<tr><td><code>type_checker</code></td></tr>
<tr class="odd"><td><code>quick_handler</code></td></tr>
<tr><td><code>map_to_storage</code></td></tr>
<tr class="odd"><td><code>check_access</code></td></tr>
<tr><td><code>check_access_ex</code></td></tr>
<tr class="odd"><td><code>insert_filter</code></td></tr>
<tr><td><code>check_authn</code></td></tr>
<tr class="odd"><td><code>check_authz</code></td></tr>
<tr><td><code>fixups</code></td></tr>
<tr class="odd"><td><code>handler</code></td></tr>
<tr><td><code>log_transaction</code></td></tr>
</table>
<p>The default is <code>log_transaction</code>. The special value
<code>all</code> is also supported, causing a message to be logged at each
phase. Not all hooks are executed for every request.</p>
<p>The optional expression allows to restrict the message if a
condition is met. The details of the expression syntax are described in
the <a href="../expr.html">ap_expr documentation</a>. References to HTTP
headers will not cause the header names to be added to the Vary header.</p>
</div>
</div>
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<p><span>Available Languages: </span><a href="../en/mod/mod_log_debug.html" title="English"> en </a> |
<a href="../fr/mod/mod_log_debug.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p>
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