You are viewing a plain text version of this content. The canonical link for it is here.
Posted to cvs@httpd.apache.org by sl...@locus.apache.org on 2000/12/11 21:56:31 UTC
cvs commit: httpd-docs-1.3/htdocs/manual/mod mod_log_config.html
slive 00/12/11 12:56:29
Modified: htdocs/manual/mod mod_log_config.html
Log:
Major update of mod_log_config docs.
Revision Changes Path
1.42 +237 -213 httpd-docs-1.3/htdocs/manual/mod/mod_log_config.html
Index: mod_log_config.html
===================================================================
RCS file: /home/cvs/httpd-docs-1.3/htdocs/manual/mod/mod_log_config.html,v
retrieving revision 1.41
retrieving revision 1.42
diff -u -d -b -u -r1.41 -r1.42
--- mod_log_config.html 2000/11/22 03:36:16 1.41
+++ mod_log_config.html 2000/12/11 20:56:25 1.42
@@ -42,10 +42,17 @@
<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 go.
+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.
@@ -53,57 +60,26 @@
<H2>Directives</H2>
-<UL>
-<LI><A HREF="#cookielog">CookieLog</A>
-<LI><A HREF="#customlog">CustomLog</A>
-<LI><A HREF="#customlog-conditional">CustomLog (conditional)</A>
-<LI><A HREF="#logformat">LogFormat</A>
-<LI><A HREF="#transferlog">TransferLog</A>
-</UL>
-
-<H3>Compatibility notes</H3>
-
<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 re-configure Apache to use configuration log
-formats.
-
-<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>As of Apache 1.3.5, this module allows conditional logging
-based upon the setting of environment variables. 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 settable on a <EM>per</EM>-logfile
-basis.
-
-<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><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>Log File Formats</H2>
-Unless told otherwise with <TT>LogFormat</TT> the log files created by
-<TT>TransferLog</TT> will be in standard "Common Log Format"
-(CLF). The contents of each line in a CLF file are explained
+<p>Unless told otherwise with <TT>LogFormat</TT>, the log files
+created by <TT>TransferLog</TT> will be in standard "Common Log
+Format" (CLF). The contents of each line in a CLF file are explained
below. Alternatively, the log file can be customized (and if multiple
log files are used, each can have a different format). Custom formats
-are set with <CODE>LogFormat</CODE> and <CODE>CustomLog</CODE>.
+are set with <CODE>LogFormat</CODE> and <CODE>CustomLog</CODE>.</p>
<H3>Common Log Format</H3>
-The Common Log Format (CLF) file contains a separate line for each
-request. A line is composed of several tokens separated by spaces:
+<p>The Common Log Format (CLF) file contains a separate line for each
+request. A line is composed of several tokens separated by spaces:</p>
<BLOCKQUOTE>
host ident authuser date request status bytes
@@ -143,12 +119,17 @@
<H3><A NAME="formats">Custom Log Formats</A></H3>
-The format argument to the <CODE>LogFormat</CODE> and
-<CODE>CustomLog</CODE> 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 `%' directives which are replaced in the log file
-by the values as follows:
+<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>
+
<PRE>
%...a: Remote IP-address
%...A: Local IP-address
@@ -178,7 +159,7 @@
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 localised)
+ 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.
@@ -186,73 +167,133 @@
%...V: The server name according to the UseCanonicalName setting.
</PRE>
-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). Note that
-there is no escaping performed on the strings from %r, %...i and
-%...o; some with long memories may remember that I thought this was
-a bad idea, once upon a time, and I'm still not comfortable with
-it, but it is difficult to see how to `do the right thing' with all
-of `%..i', unless we URL-escape everything and break with CLF.
+<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>
+<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>
-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>Some commonly used log format strings are:</p>
-<P>
+<dl>
+<dt>Common Log Format (CLF)</dt>
+<dd><CODE>"%h %l %u %t \"%r\" %>s %b"</CODE></dd>
-Note that the common log format is defined by the string <CODE>"%h %l
-%u %t \"%r\" %>s %b"</CODE>, which can be used as the basis for
-extending for format if desired (<EM>e.g.</EM>, to add extra fields at the end).
-NCSA's extended/combined log format would be <CODE>"%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\""</CODE>.
+<dt>Common Log Format with Virtual Host</dt>
+<dd><code>"%v %h %l %u %t \"%r\" %>s %b"</CODE></dd>
-<P>
+<dt>NCSA extended/combined log format</dt>
+<dd> <CODE>"%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\""</CODE></dd>
-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
+<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.
+the request.</p>
<H2>Using Multiple Log Files</H2>
-The <CODE>TransferLog</CODE> and <CODE>CustomLog</CODE> directives can
-be given more than once to log requests to multiple log files. Each
+<p>The <CODE>TransferLog</CODE> and <CODE>CustomLog</CODE> directives can
+be given more than once to log requests to multiple log files. Unless
+the conditional form of <code>CustomLog</code> is used, each
request will be logged to all the log files defined by either of these
-directives.
+directives.</p>
<H3>Use with Virtual Hosts</H3>
-If a <VirtualHost> section does not contain any
+<p>If a <VirtualHost> section does not contain any
<TT>TransferLog</TT> or <TT>CustomLog</TT> directives, the
logs defined for the main server will be used. If it does
contain one or more of these directives, requests serviced by
this virtual host will only be logged in the log files defined
within its definition, not in any of the main server's log files.
-See the examples below.
-<P>
+See the examples below.</p>
<H2>Security Considerations</H2>
-See the <A HREF="../misc/security_tips.html#serverroot">security tips</A>
+<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>
+the user that starts the server.</p>
-<HR>
+<h2>Resetting the Log Files</h2>
+<p>The access log file typically grows 1MB or more for each 10,000
+requests. It will probably be necessary to move or delete the log
+file on a regular basis. This cannot be done while the server is
+still running, because Apache will continue writing to the old log
+file. Instead, the server must be <a
+href="../stopping.html">restarted</a> after the log file is moved or
+deleted so that it will open a new log.</p>
+<p>A typical scenario is:</p>
+
+<pre>
+ mv access_log access_log.old
+ apachectl graceful
+ # wait for all requests to the old server to complete
+ # before doing anything with access_log.old
+</pre>
+
+<p>Alternatively, log files can be <a
+href="../misc/FAQ.html#rotate">rotated automatically</a> be writing
+them through a pipe to a program designed for that purpose.</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 re-configure Apache to use 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 <EM>per</EM>-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 NAME="cookielog">CookieLog</A> directive</H2>
<!--%plaintext <?INDEX {\tt CookieLog} directive> -->
-<A
+<p><A
HREF="directive-dict.html#Syntax"
REL="Help"
><STRONG>Syntax:</STRONG></A> CookieLog <EM>filename</EM><BR>
@@ -267,22 +308,22 @@
<A
HREF="directive-dict.html#Compatibility"
REL="Help"
-><STRONG>Compatibility:</STRONG></A> Only available in Apache 1.2 and above<P>
+><STRONG>Compatibility:</STRONG></A> Only available in Apache 1.2 and above</p>
-The CookieLog directive sets the filename for logging of cookies.
+<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>
+only for compatibility with <A
+HREF="mod_cookies.html">mod_cookies</A>, and is deprecated.</p>
<HR>
-<H2><A NAME="customlog">CustomLog</A> directive</H2>
-<A
+<H2><A NAME="customlog">CustomLog</A>
+<a NAME="#customlogconditional">directive</a></H2>
+<p><A
HREF="directive-dict.html#Syntax"
REL="Help"
-><STRONG>Syntax:</STRONG></A> CustomLog <EM>file-pipe</EM>
- <EM>format-or-nickname</EM><BR>
+><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"
@@ -295,81 +336,66 @@
HREF="directive-dict.html#Compatibility"
REL="Help"
><STRONG>Compatibility:</STRONG></A> Nickname only available in Apache 1.3
- or later
+ 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>
-The first argument is the filename to which log records should be
-written. This is used
-exactly like the argument to
-<A
- HREF="#transferlog"
-><SAMP>TransferLog</SAMP></A>;
-that is, it is either a full path or relative to the current
-server root.
-</P>
-<P>
-The format argument specifies a format for each line of the log file.
-The options available for the format are exactly the same as for
-the argument of the <TT>LogFormat</TT> directive. If the format
-includes any spaces (which it will do in almost all cases) it
-should be enclosed in double quotes.
-</P>
-<P>
-Instead of an actual format string, you can use a format nickname defined with
-the
-<A
- HREF="#logformat"
-><SAMP>LogFormat</SAMP></A>
-directive.
-</P>
+><STRONG>Module:</STRONG></A> mod_log_config</p>
-<HR>
-<H2><A NAME="customlog-conditional">CustomLog (conditional)</A> directive</H2>
-<A
- HREF="directive-dict.html#Syntax"
- REL="Help"
-><STRONG>Syntax:</STRONG></A> CustomLog <EM>file-pipe</EM>
- <EM>format-or-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> Only available in Apache 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>
-The behaviour of this form of the <SAMP>CustomLog</SAMP> directive is almost
-identical to the <A HREF="#customlog">standard <CODE>CustomLog</CODE></A>
-directive. The difference is that the '<CODE>env=</CODE>' clause controls
-whether a particular request will be logged in the specified file or
-not. If the specified environment variable 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 <A HREF="mod_setenvif.html">mod_setenvif</A> and/or
-<A HREF="mod_rewrite.html">mod_rewrite</A> 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>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>
+<dd>A filename, relative to the
+<a href="core.html#serverroot">ServerRoot</a>.</dd>
+
+<dt><em>pipe</em>
+<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>
+
+<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 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 <A HREF="mod_setenvif.html">mod_setenvif</A> and/or <A
+HREF="mod_rewrite.html">mod_rewrite</A> 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>
<PRE>
SetEnvIf Request_URI \.gif$ gif-image
@@ -380,10 +406,11 @@
<HR>
<H2><A NAME="logformat">LogFormat</A> directive</H2>
<!--%plaintext <?INDEX {\tt LogFormat} directive> -->
-<A
+<p><A
HREF="directive-dict.html#Syntax"
REL="Help"
-><STRONG>Syntax:</STRONG></A> LogFormat <EM>format</EM> [<EM>nickname</EM>]
+><STRONG>Syntax:</STRONG></A> LogFormat <EM>format</em>|<em>nickname</EM>
+ [<EM>nickname</EM>]
<BR>
<A
HREF="directive-dict.html#Default"
@@ -407,37 +434,39 @@
<A
HREF="directive-dict.html#Module"
REL="Help"
-><STRONG>Module:</STRONG></A> mod_log_config
-<P>
-This sets the format of the default logfile named by the
-<A
- HREF="#transferlog"
-><SAMP>TransferLog</SAMP></A>
-directive . See the section on
-<A HREF="#formats">Custom Log Formats</A> for details on the format
-arguments.
-</P>
-<P>
-If you include a nickname for the format on the directive line, you can
-use it in other <SAMP>LogFormat</SAMP> and
-<A HREF="#customlog"><SAMP>CustomLog</SAMP></A>
-directives rather than repeating the entire format string.
-</P>
-<P>
-A
+><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 <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.
+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>
<HR>
<H2><A NAME="transferlog">TransferLog</A> directive</H2>
<!--%plaintext <?INDEX {\tt TransferLog} directive> -->
-<A
+<p><A
HREF="directive-dict.html#Syntax"
REL="Help"
-><STRONG>Syntax:</STRONG></A> TransferLog <EM>file-pipe</EM><BR>
+><STRONG>Syntax:</STRONG></A> TransferLog <EM>file</em>|<em>pipe</EM><BR>
<A
HREF="directive-dict.html#Default"
REL="Help"
@@ -453,27 +482,22 @@
<A
HREF="directive-dict.html#Module"
REL="Help"
-><STRONG>Module:</STRONG></A> mod_log_config<P>
+><STRONG>Module:</STRONG></A> mod_log_config</p>
-The TransferLog directive adds a log file in the format defined by the
-most recent
-<A
- HREF="#logformat"
-><SAMP>LogFormat</SAMP></A>
-directive, or Common Log Format if no other default format has been
-specified.
-<EM>File-pipe</EM> is one
-of
-<DL><DT>A filename
-<DD>A filename relative to the <A HREF="core.html#serverroot">ServerRoot</A>.
-<DT> `|' followed by a command
-<DD>A program to receive the agent log information on its standard input.
-Note the a new program will not be started for a VirtualHost if it inherits
-the TransferLog from the main server.
-</DL>
-<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.<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 specified <a
+href="#logformat">LogFormat</a> directive. 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\""
+ TranferLog logs/access_log
+</pre>
<!--#include virtual="footer.html" -->