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9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<html>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<head>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<title>Apache module mod_cgi</title>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn</head>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<body>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<!--#include virtual="header.html" -->
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<h1>Module mod_cgi</h1>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnThis module is contained in the <code>mod_cgi.c</code> file, and
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnis compiled in by default. It provides for execution of CGI scripts.
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnAny file with mime type <code>application/x-httpd-cgi</code> will be
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnprocessed by this module.
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<!--%plaintext &lt;?INDEX {\tt application/x-httpd-cgi} mime type&gt; -->
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<!--%plaintext &lt;?INDEX CGI scripts&gt; -->
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<h2>Summary</h2>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnAny file that has the mime type <code>application/x-httpd-cgi</code>
eb5a5c7888f20ad6fa4580e785308db395ef6dfcSurya Prakkior handler <code>cgi-script</code> (Apache 1.1 or later)
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnwill be treated as a CGI script, and run by the server, with its output
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnbeing returned to the client. Files acquire this type either by
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnhaving a name ending in an extension defined by the
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<A HREF="mod_mime.html#addtype">AddType</A> directive, or by being in
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnna <A HREF="mod_alias.html#scriptalias">ScriptAlias</A> directory. <p>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnWhen the server invokes a CGI script, it will add a variable called
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<code>DOCUMENT_ROOT</code> to the environment. This variable will contain the
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnvalue of the <A HREF="core.html#documentroot">DocumentRoot</A>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnconfiguration variable.
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<h2>CGI Environment variables</h2>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnThe server will set the CGI environment variables as described in the CGI
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnspecification, with the following provisos:
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<dl>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<dt>REMOTE_HOST
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<dd>This will only be set if the server has not been compiled with
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<code>MINIMAL_DNS</code>.
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<dt>REMOTE_IDENT
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<dd>This will only be set if
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<A HREF="core.html#identitycheck">IdentityCheck</A> is set to <code>on</code>.
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<dt>REMOTE_USER
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<dd>This will only be set if the CGI script is subject to authentication.
eb5a5c7888f20ad6fa4580e785308db395ef6dfcSurya Prakki</dl>
eb5a5c7888f20ad6fa4580e785308db395ef6dfcSurya Prakki<P>
eb5a5c7888f20ad6fa4580e785308db395ef6dfcSurya Prakki
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<hr>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn<a name="cgi_debug"><h2>CGI Debugging</h2></a>
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnn
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnDebugging CGI scripts has traditionally been difficult, mainly because
9acbbeaf2a1ffe5c14b244867d427714fab43c5cnnit has
not
been possible to study the output (standard output and error) for
scripts
which are failing to run properly. These directives, included in
Apache 1.2 and later, provide
more detailed logging of errors when they occur.
<hr>
<h2>CGI Logfile Format</h2>
When configured, the CGI error log logs any CGI which does not execute
properly. Each CGI script which fails to operate causes several lines
of information to be logged. The first two lines are always of the
format:
<pre>
%% [<i>time</i>] <i>request-line</i>
%% <i>HTTP-status</i> <i>CGI-script-filename</i>
</pre>
If the error is the that CGI script cannot be run, the log file will
contain
an extra two lines:
<pre>
%%error
<i>error-message</i>
</pre>
Alternatively, if the error is the result of the script returning the
incorrect header information (often due to a bug in the script), the
following information is logged:
<pre>
%request
<i>All HTTP request headers received</i>
<i>POST or PUT entity (if any)</i>
%response
<i>All headers output by the CGI script</i>
%stdout
<i>CGI standard output</i>
%stderr
<i>CGI standard error</i>
</pre>
(The %stdout and %stderr parts may be missing if the script did not
output
anything on standard output or standard error).
<hr>
<h2>Directives</h2>
<a name="scriptlog"><h3>ScriptLog</h3></a>
<b>Syntax:</b> ScriptLog <i>filename</i><br>
<b>Default:</b> none<br>
<b>Context:</b> resource config<br>
<b>Status:</b> mod_cgi
<p>
The <tt>ScriptLog</tt> directive sets the CGI script error logfile. If
no
ScriptLog is given, no error log is created. If given, any CGI errors
are
logged
into the filename given as argument. If this is a relative file or
path it is
taken relative to the server root.
<a name="scriptloglength"><h3>ScriptLogLength</h3></a>
<b>Syntax:</b> ScriptLogLength <i>size</i><br>
<b>Default:</b> 10385760<br>
<b>Context:</b> resource config<br>
<b>Status:</b> mod_cgi
<p>
<tt>ScriptLogLength</tt> can be used to limit the size of the CGI
script logfile. Since the logfile logs a lot of information per CGI
error (all request headers, all script output) it can grow to be a big
file. To prevent problems due to unbounded growth, this directive can
be used to set an maximum filesize for the CGI logfile. If the file
exceeds this size, no more information will be written to it.
<a name="scriptlogbuffer"><h3>ScriptLogBuffer</h3></a>
<b>Syntax:</b> ScriptLogBuffer <i>size</i><br>
<b>Default:</b> 1024<br>
<b>Context:</b> resource config<br>
<b>Status:</b> mod_cgi
<p>
The size of any PUR or POST entity body that is logged to the file is
limited, to prevent the log file growing too big too quickly if large
bodies are being received. By default, up to 1024 bytes are logged,
but this can be changed with this directive.
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