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243 lines
7.3 KiB
HTML
243 lines
7.3 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<TITLE>Apache module mod_cgi</TITLE>
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</HEAD>
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<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
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<BODY
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#000080"
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ALINK="#FF0000"
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>
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<!--#include virtual="header.html" -->
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<H1 ALIGN="CENTER">Module mod_cgi</H1>
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<p>This module provides for execution of CGI scripts.</p>
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<P><A
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HREF="module-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> Base
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<BR>
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<A
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HREF="module-dict.html#SourceFile"
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REL="Help"
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><STRONG>Source File:</STRONG></A> mod_cgi.c
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<BR>
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<A
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HREF="module-dict.html#ModuleIdentifier"
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REL="Help"
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><STRONG>Module Identifier:</STRONG></A> cgi_module
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</P>
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<H2>Summary</H2>
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<!-- XXX: Should have references to CGI definition/RFC -->
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<!-- XXX: Should mention Options ExecCGI -->
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Any file that has the mime type <CODE>application/x-httpd-cgi</CODE>
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or handler <CODE>cgi-script</CODE> (Apache 1.1 or later)
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will be treated as a CGI script, and run by the server, with its output
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being returned to the client. Files acquire this type either by
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having a name containing an extension defined by the
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<A HREF="mod_mime.html#addtype">AddType</A> directive, or by being in
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a <A HREF="mod_alias.html#scriptalias">ScriptAlias</A> directory. <P>
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When the server invokes a CGI script, it will add a variable called
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<CODE>DOCUMENT_ROOT</CODE> to the environment. This variable will contain the
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value of the <A HREF="core.html#documentroot">DocumentRoot</A>
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configuration variable.
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<h2>Directives</h2>
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<ul>
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<li><a href="#scriptlog">ScriptLog</a></li>
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<li><a href="#scriptloglength">ScriptLogLength</a></li>
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<li><a href="#scriptlogbuffer">ScriptLogBuffer</a></li>
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</ul>
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<p>See also: <a href="core.html#options">Options</a>, <a
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href="mod_alias.html#scriptalias">ScriptAlias</a>, <a
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href="mod_mime.html#addtype">AddType</a> and <a
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href="mod_mime.html#addhandler">AddHandler</a>.
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<H2>CGI Environment variables</H2>
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The server will set the CGI environment variables as described in the
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<A HREF="http://hoohoo.ncsa.uiuc.edu/cgi/">CGI specification</A>, with the
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following provisions:
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<DL>
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<DT>REMOTE_HOST
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<DD>This will only be set if <A HREF="core.html#hostnamelookups"><CODE>HostnameLookups</CODE></A>
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is set to <CODE>on</CODE> (it is off by default), and if a reverse DNS
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lookup of the accessing host's address indeed finds a host name.
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<DT>REMOTE_IDENT
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<DD>This will only be set if
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<A HREF="core.html#identitycheck">IdentityCheck</A> is set to <CODE>on</CODE>
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and the accessing host supports the ident protocol. Note that the contents
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of this variable cannot be relied upon because it can easily be faked, and if
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there is a proxy between the client and the server, it is usually
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totally useless.
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<DT>REMOTE_USER
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<DD>This will only be set if the CGI script is subject to authentication.
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</DL>
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<P>
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<H2><A NAME="cgi_debug">CGI Debugging</A></H2>
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Debugging CGI scripts has traditionally been difficult, mainly because
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it has
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not
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been possible to study the output (standard output and error) for
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scripts
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which are failing to run properly. These directives, included in
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Apache 1.2 and later, provide
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more detailed logging of errors when they occur.
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<H2>CGI Logfile Format</H2>
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When configured, the CGI error log logs any CGI which does not execute
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properly. Each CGI script which fails to operate causes several lines
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of information to be logged. The first two lines are always of the
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format:
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<PRE>
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%% [<EM>time</EM>] <EM>request-line</EM>
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%% <EM>HTTP-status</EM> <EM>CGI-script-filename</EM>
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</PRE>
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If the error is that CGI script cannot be run, the log file will
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contain
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an extra two lines:
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<PRE>
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%%error
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<EM>error-message</EM>
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</PRE>
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Alternatively, if the error is the result of the script returning
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incorrect header information (often due to a bug in the script), the
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following information is logged:
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<PRE>
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%request
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<EM>All HTTP request headers received</EM>
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<EM>POST or PUT entity (if any)</EM>
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%response
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<EM>All headers output by the CGI script</EM>
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%stdout
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<EM>CGI standard output</EM>
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%stderr
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<EM>CGI standard error</EM>
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</PRE>
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(The %stdout and %stderr parts may be missing if the script did not
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output
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anything on standard output or standard error).
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<HR>
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<H3><A NAME="scriptlog">ScriptLog</A> directive</H3>
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<A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> ScriptLog <EM>filename</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> none<BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> mod_cgi
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<P>
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The <TT>ScriptLog</TT> directive sets the CGI script error logfile.
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If no ScriptLog is given, no error log is created. If given, any
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CGI errors are logged into the filename given as argument. If this
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is a relative file or path it is taken relative to the server root.
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<P>This log will be opened as the user the child processes run as,
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ie. the user specified in the main <A HREF="core.html#User">User</A>
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directive. This means that either the directory the script log is
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in needs to be writable by that user or the file needs to be manually
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created and set to be writable by that user. If you place the
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script log in your main logs directory, do <STRONG>NOT</STRONG>
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change the directory permissions to make it writable by the user
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the child processes run as.</P>
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<P>Note that script logging is meant to be a debugging feature when
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writing CGI scripts, and is not meant to be activated continuously on
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running servers. It is not optimized for speed or efficiency, and may
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have security problems if used in a manner other than that for which
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it was designed.</P>
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<hr>
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<H3><A NAME="scriptloglength">ScriptLogLength</A> directive</H3>
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<A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> ScriptLogLength <EM>bytes</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> 10385760<BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> mod_cgi
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<P>
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<TT>ScriptLogLength</TT> can be used to limit the size of the CGI
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script logfile. Since the logfile logs a lot of information per CGI
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error (all request headers, all script output) it can grow to be a big
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file. To prevent problems due to unbounded growth, this directive can
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be used to set an maximum file-size for the CGI logfile. If the file
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exceeds this size, no more information will be written to it.
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<hr>
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<H3><A NAME="scriptlogbuffer">ScriptLogBuffer</A></H3>
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<A
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HREF="directive-dict.html#Syntax"
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REL="Help"
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><STRONG>Syntax:</STRONG></A> ScriptLogBuffer <EM>bytes</EM><BR>
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<A
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HREF="directive-dict.html#Default"
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REL="Help"
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><STRONG>Default:</STRONG></A> 1024<BR>
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<A
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HREF="directive-dict.html#Context"
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REL="Help"
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><STRONG>Context:</STRONG></A> server config<BR>
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<A
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HREF="directive-dict.html#Status"
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REL="Help"
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><STRONG>Status:</STRONG></A> mod_cgi
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<P>
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The size of any PUT or POST entity body that is logged to the file is
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limited, to prevent the log file growing too big too quickly if large
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bodies are being received. By default, up to 1024 bytes are logged,
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but this can be changed with this directive.
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<!--#include virtual="footer.html" -->
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</BODY>
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</HTML>
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