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14 <p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/directives.html">Directives</a> | <a href="./faq/">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p>
15 <p class="apache">Apache HTTP Server Version 2.1</p>
16 <img alt="" src="./images/feather.gif" /></div>
17 <div class="up"><a href="./"><img title="<-" alt="<-" src="./images/left.gif" /></a></div>
19 <a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs-project/">Documentation</a> > <a href="./">Version 2.1</a></div><div id="page-content"><div id="preamble"><h1>Log Files</h1>
20 <p>In order to effectively manage a web server, it is necessary
21 to get feedback about the activity and performance of the
22 server as well as any problems that may be occuring. The Apache
23 HTTP Server provides very comprehensive and flexible logging
24 capabilities. This document describes how to configure its
25 logging capabilities, and how to understand what the logs
28 <div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#security">Security Warning</a></li>
29 <li><img alt="" src="./images/down.gif" /> <a href="#errorlog">Error Log</a></li>
30 <li><img alt="" src="./images/down.gif" /> <a href="#accesslog">Access Log</a></li>
31 <li><img alt="" src="./images/down.gif" /> <a href="#rotation">Log Rotation</a></li>
32 <li><img alt="" src="./images/down.gif" /> <a href="#piped">Piped Logs</a></li>
33 <li><img alt="" src="./images/down.gif" /> <a href="#virtualhost">Virtual Hosts</a></li>
34 <li><img alt="" src="./images/down.gif" /> <a href="#other">Other Log Files</a></li>
36 <div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
38 <h2><a name="security" id="security">Security Warning</a></h2>
41 <p>Anyone who can write to the directory where Apache is
42 writing a log file can almost certainly gain access to the uid
43 that the server is started as, which is normally root. Do
44 <em>NOT</em> give people write access to the directory the logs
45 are stored in without being aware of the consequences; see the
46 <a href="misc/security_tips.html">security tips</a> document
49 <p>In addition, log files may contain information supplied
50 directly by the client, without escaping. Therefore, it is
51 possible for malicious clients to insert control-characters in
52 the log files, so care must be taken in dealing with raw
54 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
56 <h2><a name="errorlog" id="errorlog">Error Log</a></h2>
59 <table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td /><td><ul><li><code class="directive"><a href="./mod/core.html#errorlog">ErrorLog</a></code></li><li><code class="directive"><a href="./mod/core.html#loglevel">LogLevel</a></code></li></ul></td></tr></table>
61 <p>The server error log, whose name and location is set by the
62 <code class="directive"><a href="./mod/core.html#errorlog">ErrorLog</a></code> directive, is the
63 most important log file. This is the place where Apache httpd
64 will send diagnostic information and record any errors that it
65 encounters in processing requests. It is the first place to
66 look when a problem occurs with starting the server or with the
67 operation of the server, since it will often contain details of
68 what went wrong and how to fix it.</p>
70 <p>The error log is usually written to a file (typically
71 <code>error_log</code> on unix systems and
72 <code>error.log</code> on Windows and OS/2). On unix systems it
73 is also possible to have the server send errors to
74 <code>syslog</code> or <a href="#piped">pipe them to a
77 <p>The format of the error log is relatively free-form and
78 descriptive. But there is certain information that is contained
79 in most error log entries. For example, here is a typical
82 <div class="example"><p><code>
83 [Wed Oct 11 14:32:52 2000] [error] [client 127.0.0.1]
84 client denied by server configuration:
85 /export/home/live/ap/htdocs/test
88 <p>The first item in the log entry is the date and time of the
89 message. The second entry lists the severity of the error being
90 reported. The <code class="directive"><a href="./mod/core.html#loglevel">LogLevel</a></code>
91 directive is used to control the types of errors that are sent
92 to the error log by restricting the severity level. The third
93 entry gives the IP address of the client that generated the
94 error. Beyond that is the message itself, which in this case
95 indicates that the server has been configured to deny the
96 client access. The server reports the file-system path (as
97 opposed to the web path) of the requested document.</p>
99 <p>A very wide variety of different messages can appear in the
100 error log. Most look similar to the example above. The error
101 log will also contain debugging output from CGI scripts. Any
102 information written to <code>stderr</code> by a CGI script will
103 be copied directly to the error log.</p>
105 <p>It is not possible to customize the error log by adding or
106 removing information. However, error log entries dealing with
107 particular requests have corresponding entries in the <a href="#accesslog">access log</a>. For example, the above example
108 entry corresponds to an access log entry with status code 403.
109 Since it is possible to customize the access log, you can
110 obtain more information about error conditions using that log
113 <p>During testing, it is often useful to continuously monitor
114 the error log for any problems. On unix systems, you can
115 accomplish this using:</p>
117 <div class="example"><p><code>
120 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
121 <div class="section">
122 <h2><a name="accesslog" id="accesslog">Access Log</a></h2>
125 <table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="./mod/mod_log_config.html">mod_log_config</a></code></li><li><code class="module"><a href="./mod/mod_setenvif.html">mod_setenvif</a></code></li></ul></td><td><ul><li><code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code></li><li><code class="directive"><a href="./mod/mod_log_config.html#logformat">LogFormat</a></code></li><li><code class="directive"><a href="./mod/mod_setenvif.html#setenvif">SetEnvIf</a></code></li></ul></td></tr></table>
127 <p>The server access log records all requests processed by the
128 server. The location and content of the access log are
129 controlled by the <code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code>
130 directive. The <code class="directive"><a href="./mod/mod_log_config.html#logformat">LogFormat</a></code>
131 directive can be used to simplify the selection of
132 the contents of the logs. This section describes how to configure the server
133 to record information in the access log.</p>
135 <p>Of course, storing the information in the access log is only
136 the start of log management. The next step is to analyze this
137 information to produce useful statistics. Log analysis in
138 general is beyond the scope of this document, and not really
139 part of the job of the web server itself. For more information
140 about this topic, and for applications which perform log
141 analysis, check the <a href="http://dmoz.org/Computers/Software/Internet/Site_Management/Log_analysis/">
142 Open Directory</a> or <a href="http://dir.yahoo.com/Computers_and_Internet/Software/Internet/World_Wide_Web/Servers/Log_Analysis_Tools/">
145 <p>Various versions of Apache httpd have used other modules and
146 directives to control access logging, including
147 mod_log_referer, mod_log_agent, and the
148 <code>TransferLog</code> directive. The <code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code> directive now subsumes
149 the functionality of all the older directives.</p>
151 <p>The format of the access log is highly configurable. The format
152 is specified using a format string that looks much like a C-style
153 printf(1) format string. Some examples are presented in the next
154 sections. For a complete list of the possible contents of the
155 format string, see the <code class="module"><a href="./mod/mod_log_config.html">mod_log_config</a></code> <a href="mod/mod_log_config.html#formats">format strings</a>.</p>
157 <h3><a name="common" id="common">Common Log Format</a></h3>
160 <p>A typical configuration for the access log might look as
163 <div class="example"><p><code>
164 LogFormat "%h %l %u %t \"%r\" %>s %b" common<br />
165 CustomLog logs/access_log common
168 <p>This defines the <em>nickname</em> <code>common</code> and
169 associates it with a particular log format string. The format
170 string consists of percent directives, each of which tell the
171 server to log a particular piece of information. Literal
172 characters may also be placed in the format string and will be
173 copied directly into the log output. The quote character
174 (<code>"</code>) must be escaped by placing a back-slash before
175 it to prevent it from being interpreted as the end of the
176 format string. The format string may also contain the special
177 control characters "<code>\n</code>" for new-line and
178 "<code>\t</code>" for tab.</p>
180 <p>The <code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code>
181 directive sets up a new log file using the defined
182 <em>nickname</em>. The filename for the access log is relative to
183 the <code class="directive"><a href="./mod/core.html#serverroot">ServerRoot</a></code> unless it
184 begins with a slash.</p>
186 <p>The above configuration will write log entries in a format
187 known as the Common Log Format (CLF). This standard format can
188 be produced by many different web servers and read by many log
189 analysis programs. The log file entries produced in CLF will
190 look something like this:</p>
192 <div class="example"><p><code>
193 127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET
194 /apache_pb.gif HTTP/1.0" 200 2326
197 <p>Each part of this log entry is described below.</p>
200 <dt><code>127.0.0.1</code> (<code>%h</code>)</dt>
202 <dd>This is the IP address of the client (remote host) which
203 made the request to the server. If <code class="directive"><a href="./mod/core.html#hostnamelookups">HostnameLookups</a></code> is
204 set to <code>On</code>, then the server will try to determine
205 the hostname and log it in place of the IP address. However,
206 this configuration is not recommended since it can
207 significantly slow the server. Instead, it is best to use a
208 log post-processor such as <a href="programs/logresolve.html">logresolve</a> to determine
209 the hostnames. The IP address reported here is not
210 necessarily the address of the machine at which the user is
211 sitting. If a proxy server exists between the user and the
212 server, this address will be the address of the proxy, rather
213 than the originating machine.</dd>
215 <dt><code>-</code> (<code>%l</code>)</dt>
217 <dd>The "hyphen" in the output indicates that the requested
218 piece of information is not available. In this case, the
219 information that is not available is the RFC 1413 identity of
220 the client determined by <code>identd</code> on the clients
221 machine. This information is highly unreliable and should
222 almost never be used except on tightly controlled internal
223 networks. Apache httpd will not even attempt to determine
224 this information unless <code class="directive"><a href="./mod/core.html#identitycheck">IdentityCheck</a></code> is set
225 to <code>On</code>.</dd>
227 <dt><code>frank</code> (<code>%u</code>)</dt>
229 <dd>This is the userid of the person requesting the document
230 as determined by HTTP authentication. The same value is
231 typically provided to CGI scripts in the
232 <code>REMOTE_USER</code> environment variable. If the status
233 code for the request (see below) is 401, then this value
234 should not be trusted because the user is not yet
235 authenticated. If the document is not password protected,
236 this entry will be "<code>-</code>" just like the previous
239 <dt><code>[10/Oct/2000:13:55:36 -0700]</code>
240 (<code>%t</code>)</dt>
243 The time that the server finished processing the request.
247 <code>[day/month/year:hour:minute:second zone]<br />
249 month = 3*letter<br />
252 minute = 2*digit<br />
253 second = 2*digit<br />
254 zone = (`+' | `-') 4*digit</code>
256 It is possible to have the time displayed in another format
257 by specifying <code>%{format}t</code> in the log format
258 string, where <code>format</code> is as in
259 <code>strftime(3)</code> from the C standard library.
262 <dt><code>"GET /apache_pb.gif HTTP/1.0"</code>
263 (<code>\"%r\"</code>)</dt>
265 <dd>The request line from the client is given in double
266 quotes. The request line contains a great deal of useful
267 information. First, the method used by the client is
268 <code>GET</code>. Second, the client requested the resource
269 <code>/apache_pb.gif</code>, and third, the client used the
270 protocol <code>HTTP/1.0</code>. It is also possible to log
271 one or more parts of the request line independently. For
272 example, the format string "<code>%m %U%q %H</code>" will log
273 the method, path, query-string, and protocol, resulting in
274 exactly the same output as "<code>%r</code>".</dd>
276 <dt><code>200</code> (<code>%>s</code>)</dt>
278 <dd>This is the status code that the server sends back to the
279 client. This information is very valuable, because it reveals
280 whether the request resulted in a successful response (codes
281 beginning in 2), a redirection (codes beginning in 3), an
282 error caused by the client (codes beginning in 4), or an
283 error in the server (codes beginning in 5). The full list of
284 possible status codes can be found in the <a href="http://www.w3.org/Protocols/rfc2616/rfc2616.txt">HTTP
285 specification</a> (RFC2616 section 10).</dd>
287 <dt><code>2326</code> (<code>%b</code>)</dt>
289 <dd>The last entry indicates the size of the object returned
290 to the client, not including the response headers. If no
291 content was returned to the client, this value will be
292 "<code>-</code>". To log "<code>0</code>" for no content, use
293 <code>%B</code> instead.</dd>
297 <h3><a name="combined" id="combined">Combined Log Format</a></h3>
300 <p>Another commonly used format string is called the Combined
301 Log Format. It can be used as follows.</p>
303 <div class="example"><p><code>
304 LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\"
305 \"%{User-agent}i\"" combined<br />
306 CustomLog log/acces_log combined
309 <p>This format is exactly the same as the Common Log Format,
310 with the addition of two more fields. Each of the additional
311 fields uses the percent-directive
312 <code>%{<em>header</em>}i</code>, where <em>header</em> can be
313 any HTTP request header. The access log under this format will
316 <div class="example"><p><code>
317 127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET
318 /apache_pb.gif HTTP/1.0" 200 2326
319 "http://www.example.com/start.html" "Mozilla/4.08 [en]
323 <p>The additional fields are:</p>
326 <dt><code>"http://www.example.com/start.html"</code>
327 (<code>\"%{Referer}i\"</code>)</dt>
329 <dd>The "Referer" (sic) HTTP request header. This gives the
330 site that the client reports having been referred from. (This
331 should be the page that links to or includes
332 <code>/apache_pb.gif</code>).</dd>
334 <dt><code>"Mozilla/4.08 [en] (Win98; I ;Nav)"</code>
335 (<code>\"%{User-agent}i\"</code>)</dt>
337 <dd>The User-Agent HTTP request header. This is the
338 identifying information that the client browser reports about
343 <h3><a name="multiple" id="multiple">Multiple Access Logs</a></h3>
346 <p>Multiple access logs can be created simply by specifying
347 multiple <code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code>
348 directives in the configuration
349 file. For example, the following directives will create three
350 access logs. The first contains the basic CLF information,
351 while the second and third contain referer and browser
352 information. The last two <code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code> lines show how
353 to mimic the effects of the <code>ReferLog</code> and <code>AgentLog</code> directives.</p>
355 <div class="example"><p><code>
356 LogFormat "%h %l %u %t \"%r\" %>s %b" common<br />
357 CustomLog logs/access_log common<br />
358 CustomLog logs/referer_log "%{Referer}i -> %U"<br />
359 CustomLog logs/agent_log "%{User-agent}i"
362 <p>This example also shows that it is not necessary to define a
363 nickname with the <code class="directive"><a href="./mod/mod_log_config.html#logformat">LogFormat</a></code> directive. Instead,
364 the log format can be specified directly in the <code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code> directive.</p>
367 <h3><a name="conditional" id="conditional">Conditional Logs</a></h3>
370 <p>There are times when it is convenient to exclude certain
371 entries from the access logs based on characteristics of the
372 client request. This is easily accomplished with the help of <a href="env.html">environment variables</a>. First, an
373 environment variable must be set to indicate that the request
374 meets certain conditions. This is usually accomplished with
375 <code class="directive"><a href="./mod/mod_setenvif.html#setenvif">SetEnvIf</a></code>. Then the
376 <code>env=</code> clause of the <code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code> directive is used to
377 include or exclude requests where the environment variable is
378 set. Some examples:</p>
380 <div class="example"><p><code>
381 # Mark requests from the loop-back interface<br />
382 SetEnvIf Remote_Addr "127\.0\.0\.1" dontlog<br />
383 # Mark requests for the robots.txt file<br />
384 SetEnvIf Request_URI "^/robots\.txt$" dontlog<br />
385 # Log what remains<br />
386 CustomLog logs/access_log common env=!dontlog
389 <p>As another example, consider logging requests from
390 english-speakers to one log file, and non-english speakers to a
391 different log file.</p>
393 <div class="example"><p><code>
394 SetEnvIf Accept-Language "en" english<br />
395 CustomLog logs/english_log common env=english<br />
396 CustomLog logs/non_english_log common env=!english
399 <p>Although we have just shown that conditional logging is very
400 powerful and flexibly, it is not the only way to control the
401 contents of the logs. Log files are more useful when they
402 contain a complete record of server activity. It is often
403 easier to simply post-process the log files to remove requests
404 that you do not want to consider.</p>
406 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
407 <div class="section">
408 <h2><a name="rotation" id="rotation">Log Rotation</a></h2>
411 <p>On even a moderately busy server, the quantity of
412 information stored in the log files is very large. The access
413 log file typically grows 1 MB or more per 10,000 requests. It
414 will consequently be necessary to periodically rotate the log
415 files by moving or deleting the existing logs. This cannot be
416 done while the server is running, because Apache will continue
417 writing to the old log file as long as it holds the file open.
418 Instead, the server must be <a href="stopping.html">restarted</a> after the log files are
419 moved or deleted so that it will open new log files.</p>
421 <p>By using a <em>graceful</em> restart, the server can be
422 instructed to open new log files without losing any existing or
423 pending connections from clients. However, in order to
424 accomplish this, the server must continue to write to the old
425 log files while it finishes serving old requests. It is
426 therefore necessary to wait for some time after the restart
427 before doing any processing on the log files. A typical
428 scenario that simply rotates the logs and compresses the old
429 logs to save space is:</p>
431 <div class="example"><p><code>
432 mv access_log access_log.old<br />
433 mv error_log error_log.old<br />
434 apachectl graceful<br />
436 gzip access_log.old error_log.old
439 <p>Another way to perform log rotation is using <a href="#piped">piped logs</a> as discussed in the next
441 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
442 <div class="section">
443 <h2><a name="piped" id="piped">Piped Logs</a></h2>
446 <p>Apache httpd is capable of writing error and access log
447 files through a pipe to another process, rather than directly
448 to a file. This capability dramatically increases the
449 flexibility of logging, without adding code to the main server.
450 In order to write logs to a pipe, simply replace the filename
451 with the pipe character "<code>|</code>", followed by the name
452 of the executable which should accept log entries on its
453 standard input. Apache will start the piped-log process when
454 the server starts, and will restart it if it crashes while the
455 server is running. (This last feature is why we can refer to
456 this technique as "reliable piped logging".)</p>
458 <p>Piped log processes are spawned by the parent Apache httpd
459 process, and inherit the userid of that process. This means
460 that piped log programs usually run as root. It is therefore
461 very important to keep the programs simple and secure.</p>
463 <p>One important use of piped logs is to allow log rotation
464 without having to restart the server. The Apache HTTP Server
465 includes a simple program called <a href="programs/rotatelogs.html">rotatelogs</a> for this
466 purpose. For example, to rotate the logs every 24 hours, you
469 <div class="example"><p><code>
470 CustomLog "|/usr/local/apache/bin/rotatelogs
471 /var/log/access_log 86400" common
474 <p>Notice that quotes are used to enclose the entire command
475 that will be called for the pipe. Although these examples are
476 for the access log, the same technique can be used for the
479 <p>A similar but much more flexible log rotation program
480 called <a href="http://www.cronolog.org/">cronolog</a>
481 is available at an external site.</p>
483 <p>As with conditional logging, piped logs are a very powerful
484 tool, but they should not be used where a simpler solution like
485 off-line post-processing is available.</p>
486 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
487 <div class="section">
488 <h2><a name="virtualhost" id="virtualhost">Virtual Hosts</a></h2>
491 <p>When running a server with many <a href="vhosts/">virtual
492 hosts</a>, there are several options for dealing with log
493 files. First, it is possible to use logs exactly as in a
494 single-host server. Simply by placing the logging directives
495 outside the <code class="directive"><a href="./mod/core.html#virtualhost"><VirtualHost></a></code> sections in the
496 main server context, it is possible to log all requests in the
497 same access log and error log. This technique does not allow
498 for easy collection of statistics on individual virtual
501 <p>If <code class="directive"><a href="./mod/mod_log_config.html#customlog">CustomLog</a></code>
502 or <code class="directive"><a href="./mod/core.html#errorlog">ErrorLog</a></code>
503 directives are placed inside a
504 <code class="directive"><a href="./mod/core.html#virtualhost"><VirtualHost></a></code>
505 section, all requests or errors for that virtual host will be
506 logged only to the specified file. Any virtual host which does
507 not have logging directives will still have its requests sent
508 to the main server logs. This technique is very useful for a
509 small number of virtual hosts, but if the number of hosts is
510 very large, it can be complicated to manage. In addition, it
511 can often create problems with <a href="vhosts/fd-limits.html">insufficient file
514 <p>For the access log, there is a very good compromise. By
515 adding information on the virtual host to the log format
516 string, it is possible to log all hosts to the same log, and
517 later split the log into individual files. For example,
518 consider the following directives.</p>
520 <div class="example"><p><code>
521 LogFormat "%v %l %u %t \"%r\" %>s %b"
523 CustomLog logs/access_log comonvhost
526 <p>The <code>%v</code> is used to log the name of the virtual
527 host that is serving the request. Then a program like <a href="programs/other.html">split-logfile</a> can be used to
528 post-process the access log in order to split it into one file
529 per virtual host.</p>
530 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
531 <div class="section">
532 <h2><a name="other" id="other">Other Log Files</a></h2>
535 <table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="./mod/mod_cgi.html">mod_cgi</a></code></li><li><code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code></li></ul></td><td><ul><li><code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewritelog">RewriteLog</a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewriteloglevel">RewriteLogLevel</a></code></li><li><code class="directive"><a href="./mod/mod_cgi.html#scriptlog">ScriptLog</a></code></li><li><code class="directive"><a href="./mod/mod_cgi.html#scriptlogbuffer">ScriptLogBuffer</a></code></li><li><code class="directive"><a href="./mod/mod_cgi.html#scriptloglength">ScriptLogLength</a></code></li></ul></td></tr></table>
537 <h3><a name="pidfile" id="pidfile">PID File</a></h3>
540 <p>On startup, Apache httpd saves the process id of the parent
541 httpd process to the file <code>logs/httpd.pid</code>. This
542 filename can be changed with the <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code> directive. The
543 process-id is for use by the administrator in restarting and
544 terminating the daemon by sending signals to the parent
545 process; on Windows, use the -k command line option instead.
546 For more information see the <a href="stopping.html">Stopping
547 and Restarting</a> page.</p>
550 <h3><a name="scriptlog" id="scriptlog">Script Log</a></h3>
553 <p>In order to aid in debugging, the
554 <code class="directive"><a href="./mod/mod_cgi.html#scriptlog">ScriptLog</a></code> directive
555 allows you to record the input to and output from CGI scripts.
556 This should only be used in testing - not for live servers.
557 More information is available in the <a href="mod/mod_cgi.html">mod_cgi</a> documentation.</p>
560 <h3><a name="rewritelog" id="rewritelog">Rewrite Log</a></h3>
563 <p>When using the powerful and complex features of <a href="mod/mod_rewrite.html">mod_rewrite</a>, it is almost
564 always necessary to use the <code class="directive"><a href="./mod/mod_rewrite.html#rewritelog">RewriteLog</a></code> to help
565 in debugging. This log file produces a detailed analysis of how
566 the rewriting engine transforms requests. The level of detail
567 is controlled by the <code class="directive"><a href="./mod/mod_rewrite.html#rewriteloglevel">RewriteLogLevel</a></code> directive.</p>
571 <p class="apache">Maintained by the <a href="http://httpd.apache.org/docs-project/">Apache HTTP Server Documentation Project</a></p>
572 <p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/directives.html">Directives</a> | <a href="./faq/">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p></div>
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