<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
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="core">ErrorLog</directive>
<directive module="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
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>
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>
<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>
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
sections. For a complete list of the possible contents of the
format string, see the <module>mod_log_config</module> <a
href="mod/mod_log_config.html#formats">format strings</a>.</p>
-
+
<section id="common">
<title>Common Log Format</title>
-
+
<p>A typical configuration for the access log might look as
follows.</p>
LogFormat "%h %l %u %t \"%r\" %>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
<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
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>
<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>
<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
</example>
<p>The additional fields are:</p>
-
+
<dl>
<dt><code>"http://www.example.com/start.html"</code>
(<code>\"%{Referer}i\"</code>)</dt>
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="mod_log_config">CustomLog</directive>
directives in the configuration
the log format can be specified directly in the <directive
module="mod_log_config">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
that you do not want to consider.</p>
</section>
</section>
-
+
<section id="rotation">
<title>Log Rotation</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
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
CustomLog "|/usr/local/apache/bin/rotatelogs
/var/log/access_log 86400" 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
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
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>
<directive module="mod_cgi">ScriptLogLength</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
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.
More information is available in the <a
href="mod/mod_cgi.html">mod_cgi</a> documentation.</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
projects / apache / commitdiff