APACHE_1_3_42/htdocs/manual/mod/mod_cgi.html.en - httpd - Git at Google

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     <h1 align="CENTER">Module mod_cgi</h1>

     <p>This module provides for execution of CGI scripts.</p>

     <p><a href="module-dict.html#Status"
     rel="Help"><strong>Status:</strong></a> Base<br />
      <a href="module-dict.html#SourceFile"
     rel="Help"><strong>Source File:</strong></a> mod_cgi.c<br />
      <a href="module-dict.html#ModuleIdentifier"
     rel="Help"><strong>Module Identifier:</strong></a>
     cgi_module</p>

     <h2>Summary</h2>
     <!-- XXX: Should have references to CGI definition/RFC -->
     Any file that has the mime type
     <code>application/x-httpd-cgi</code> or handler
     <code>cgi-script</code> (Apache 1.1 or later) will be treated
     as a CGI script, and run by the server, with its output being
     returned to the client. Files acquire this type either by
     having a name containing an extension defined by the <a
     href="mod_mime.html#addtype">AddType</a> directive, or by being
     in a <a href="mod_alias.html#scriptalias">ScriptAlias</a>
     directory. Files that are not in a <a
     href="mod_alias.html#scriptalias">ScriptAlias</a> directory,
     but which are of type <code>application/x-httpd-cgi</code> by
     virtue of an <code>AddType</code> directive, will still not be
     executed by the server unless <code>Options ExecCGI</code> is
     enabled. See the <a
     href="core.html#options"><code>Options</code></a> directive for
     more details.

     <p>When the server invokes a CGI script, it will add a variable
     called <code>DOCUMENT_ROOT</code> to the environment. This
     variable will contain the value of the <a
     href="core.html#documentroot">DocumentRoot</a> configuration
     variable.</p>

     <p>For an introduction to using CGI scripts with Apache, see
     our tutorial on <a href="../howto/cgi.html">Dynamic Content
     with CGI</a>.</p>

     <h2>Directives</h2>

     <ul>
       <li><a href="#scriptlog">ScriptLog</a></li>

       <li><a href="#scriptloglength">ScriptLogLength</a></li>

       <li><a href="#scriptlogbuffer">ScriptLogBuffer</a></li>
     </ul>

     <p>See also: <a href="core.html#options">Options</a>, <a
     href="mod_alias.html#scriptalias">ScriptAlias</a>, <a
     href="mod_mime.html#addtype">AddType</a> and <a
     href="mod_mime.html#addhandler">AddHandler</a>.</p>

     <h2>CGI Environment variables</h2>
     The server will set the CGI environment variables as described
     in the <a href="http://hoohoo.ncsa.uiuc.edu/cgi/">CGI
     specification</a>, with the following provisions:

     <dl>
       <dt>REMOTE_HOST</dt>

       <dd>This will only be set if <a
       href="core.html#hostnamelookups"><code>HostnameLookups</code></a>
       is set to <code>on</code> (it is off by default), and if a
       reverse DNS lookup of the accessing host's address indeed
       finds a host name.</dd>

       <dt>REMOTE_IDENT</dt>

       <dd>This will only be set if <a
       href="core.html#identitycheck">IdentityCheck</a> is set to
       <code>on</code> and the accessing host supports the ident
       protocol. Note that the contents of this variable cannot be
       relied upon because it can easily be faked, and if there is a
       proxy between the client and the server, it is usually
       totally useless.</dd>

       <dt>REMOTE_USER</dt>

       <dd>This will only be set if the CGI script is subject to
       authentication.</dd>
     </dl>

     <h2><a id="cgi_debug" name="cgi_debug">CGI Debugging</a></h2>
     Debugging CGI scripts has traditionally been difficult, mainly
     because it 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.

     <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>
   %% [<em>time</em>] <em>request-line</em>
   %% <em>HTTP-status</em> <em>CGI-script-filename</em>
 </pre>
     If the error is that CGI script cannot be run, the log file
     will contain an extra two lines:
 <pre>
   %%error
   <em>error-message</em>
 </pre>
     Alternatively, if the error is the result of the script
     returning incorrect header information (often due to a bug in
     the script), the following information is logged:
 <pre>
   %request
   <em>All HTTP request headers received</em>
   <em>POST or PUT entity (if any)</em>
   %response
   <em>All headers output by the CGI script</em>
   %stdout
   <em>CGI standard output</em>
   %stderr
   <em>CGI standard error</em>
 </pre>
     (The %stdout and %stderr parts may be missing if the script did
     not output anything on standard output or standard error).
     <hr />

     <h3><a id="scriptlog" name="scriptlog">ScriptLog</a>
     directive</h3>
     <a href="directive-dict.html#Syntax"
     rel="Help"><strong>Syntax:</strong></a> ScriptLog
     <em>filename</em><br />
      <a href="directive-dict.html#Default"
     rel="Help"><strong>Default:</strong></a> none<br />
      <a href="directive-dict.html#Context"
     rel="Help"><strong>Context:</strong></a> server config<br />
      <a href="directive-dict.html#Status"
     rel="Help"><strong>Status:</strong></a> 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.</p>

     <p>This log will be opened as the user the child processes run
     as, ie. the user specified in the main <a
     href="core.html#user">User</a> directive. This means that
     either the directory the script log is in needs to be writable
     by that user or the file needs to be manually created and set
     to be writable by that user. If you place the script log in
     your main logs directory, do <strong>NOT</strong> change the
     directory permissions to make it writable by the user the child
     processes run as.</p>

     <p>Note that script logging is meant to be a debugging feature
     when writing CGI scripts, and is not meant to be activated
     continuously on running servers. It is not optimized for speed
     or efficiency, and may have security problems if used in a
     manner other than that for which it was designed.</p>
     <hr />

     <h3><a id="scriptloglength"
     name="scriptloglength">ScriptLogLength</a> directive</h3>
     <a href="directive-dict.html#Syntax"
     rel="Help"><strong>Syntax:</strong></a> ScriptLogLength
     <em>bytes</em><br />
      <a href="directive-dict.html#Default"
     rel="Help"><strong>Default:</strong></a> 10385760<br />
      <a href="directive-dict.html#Context"
     rel="Help"><strong>Context:</strong></a> server config<br />
      <a href="directive-dict.html#Status"
     rel="Help"><strong>Status:</strong></a> 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 file-size for the CGI logfile. If the file exceeds this
     size, no more information will be written to it.</p>
     <hr />

     <h3><a id="scriptlogbuffer"
     name="scriptlogbuffer">ScriptLogBuffer</a></h3>
     <a href="directive-dict.html#Syntax"
     rel="Help"><strong>Syntax:</strong></a> ScriptLogBuffer
     <em>bytes</em><br />
      <a href="directive-dict.html#Default"
     rel="Help"><strong>Default:</strong></a> 1024<br />
      <a href="directive-dict.html#Context"
     rel="Help"><strong>Context:</strong></a> server config<br />
      <a href="directive-dict.html#Status"
     rel="Help"><strong>Status:</strong></a> mod_cgi

     <p>The size of any PUT 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. <!--#include virtual="footer.html" -->
     </p>
   </body>
 </html>
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	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

	<html xmlns="http://www.w3.org/1999/xhtml">
	<head>
	<meta name="generator" content="HTML Tidy, see www.w3.org" />

	<title>Apache module mod_cgi</title>
	</head>
	<!-- Background white, links blue (unvisited), navy (visited), red (active) -->

	<body bgcolor="#FFFFFF" text="#000000" link="#0000FF"
	vlink="#000080" alink="#FF0000">
	<!--#include virtual="header.html" -->

	<h1 align="CENTER">Module mod_cgi</h1>

	<p>This module provides for execution of CGI scripts.</p>

	<p><a href="module-dict.html#Status"
	rel="Help"><strong>Status:</strong></a> Base<br />
	<a href="module-dict.html#SourceFile"
	rel="Help"><strong>Source File:</strong></a> mod_cgi.c<br />
	<a href="module-dict.html#ModuleIdentifier"
	rel="Help"><strong>Module Identifier:</strong></a>
	cgi_module</p>

	<h2>Summary</h2>
	<!-- XXX: Should have references to CGI definition/RFC -->
	Any file that has the mime type
	<code>application/x-httpd-cgi</code> or handler
	<code>cgi-script</code> (Apache 1.1 or later) will be treated
	as a CGI script, and run by the server, with its output being
	returned to the client. Files acquire this type either by
	having a name containing an extension defined by the <a
	href="mod_mime.html#addtype">AddType</a> directive, or by being
	in a <a href="mod_alias.html#scriptalias">ScriptAlias</a>
	directory. Files that are not in a <a
	href="mod_alias.html#scriptalias">ScriptAlias</a> directory,
	but which are of type <code>application/x-httpd-cgi</code> by
	virtue of an <code>AddType</code> directive, will still not be
	executed by the server unless <code>Options ExecCGI</code> is
	enabled. See the <a
	href="core.html#options"><code>Options</code></a> directive for
	more details.

	<p>When the server invokes a CGI script, it will add a variable
	called <code>DOCUMENT_ROOT</code> to the environment. This
	variable will contain the value of the <a
	href="core.html#documentroot">DocumentRoot</a> configuration
	variable.</p>

	<p>For an introduction to using CGI scripts with Apache, see
	our tutorial on <a href="../howto/cgi.html">Dynamic Content
	with CGI</a>.</p>

	<h2>Directives</h2>

	<ul>
	<li><a href="#scriptlog">ScriptLog</a></li>

	<li><a href="#scriptloglength">ScriptLogLength</a></li>

	<li><a href="#scriptlogbuffer">ScriptLogBuffer</a></li>
	</ul>

	<p>See also: <a href="core.html#options">Options</a>, <a
	href="mod_alias.html#scriptalias">ScriptAlias</a>, <a
	href="mod_mime.html#addtype">AddType</a> and <a
	href="mod_mime.html#addhandler">AddHandler</a>.</p>

	<h2>CGI Environment variables</h2>
	The server will set the CGI environment variables as described
	in the <a href="http://hoohoo.ncsa.uiuc.edu/cgi/">CGI
	specification</a>, with the following provisions:

	<dl>
	<dt>REMOTE_HOST</dt>

	<dd>This will only be set if <a
	href="core.html#hostnamelookups"><code>HostnameLookups</code></a>
	is set to <code>on</code> (it is off by default), and if a
	reverse DNS lookup of the accessing host's address indeed
	finds a host name.</dd>

	<dt>REMOTE_IDENT</dt>

	<dd>This will only be set if <a
	href="core.html#identitycheck">IdentityCheck</a> is set to
	<code>on</code> and the accessing host supports the ident
	protocol. Note that the contents of this variable cannot be
	relied upon because it can easily be faked, and if there is a
	proxy between the client and the server, it is usually
	totally useless.</dd>

	<dt>REMOTE_USER</dt>

	<dd>This will only be set if the CGI script is subject to
	authentication.</dd>
	</dl>

	<h2><a id="cgi_debug" name="cgi_debug">CGI Debugging</a></h2>
	Debugging CGI scripts has traditionally been difficult, mainly
	because it 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.

	<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>
	%% [<em>time</em>] <em>request-line</em>
	%% <em>HTTP-status</em> <em>CGI-script-filename</em>
	</pre>
	If the error is that CGI script cannot be run, the log file
	will contain an extra two lines:
	<pre>
	%%error
	<em>error-message</em>
	</pre>
	Alternatively, if the error is the result of the script
	returning incorrect header information (often due to a bug in
	the script), the following information is logged:
	<pre>
	%request
	<em>All HTTP request headers received</em>
	<em>POST or PUT entity (if any)</em>
	%response
	<em>All headers output by the CGI script</em>
	%stdout
	<em>CGI standard output</em>
	%stderr
	<em>CGI standard error</em>
	</pre>
	(The %stdout and %stderr parts may be missing if the script did
	not output anything on standard output or standard error).
	<hr />

	<h3><a id="scriptlog" name="scriptlog">ScriptLog</a>
	directive</h3>
	<a href="directive-dict.html#Syntax"
	rel="Help"><strong>Syntax:</strong></a> ScriptLog
	<em>filename</em><br />
	<a href="directive-dict.html#Default"
	rel="Help"><strong>Default:</strong></a> none<br />
	<a href="directive-dict.html#Context"
	rel="Help"><strong>Context:</strong></a> server config<br />
	<a href="directive-dict.html#Status"
	rel="Help"><strong>Status:</strong></a> 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.</p>

	<p>This log will be opened as the user the child processes run
	as, ie. the user specified in the main <a
	href="core.html#user">User</a> directive. This means that
	either the directory the script log is in needs to be writable
	by that user or the file needs to be manually created and set
	to be writable by that user. If you place the script log in
	your main logs directory, do <strong>NOT</strong> change the
	directory permissions to make it writable by the user the child
	processes run as.</p>

	<p>Note that script logging is meant to be a debugging feature
	when writing CGI scripts, and is not meant to be activated
	continuously on running servers. It is not optimized for speed
	or efficiency, and may have security problems if used in a
	manner other than that for which it was designed.</p>
	<hr />

	<h3><a id="scriptloglength"
	name="scriptloglength">ScriptLogLength</a> directive</h3>
	<a href="directive-dict.html#Syntax"
	rel="Help"><strong>Syntax:</strong></a> ScriptLogLength
	<em>bytes</em><br />
	<a href="directive-dict.html#Default"
	rel="Help"><strong>Default:</strong></a> 10385760<br />
	<a href="directive-dict.html#Context"
	rel="Help"><strong>Context:</strong></a> server config<br />
	<a href="directive-dict.html#Status"
	rel="Help"><strong>Status:</strong></a> 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 file-size for the CGI logfile. If the file exceeds this
	size, no more information will be written to it.</p>
	<hr />

	<h3><a id="scriptlogbuffer"
	name="scriptlogbuffer">ScriptLogBuffer</a></h3>
	<a href="directive-dict.html#Syntax"
	rel="Help"><strong>Syntax:</strong></a> ScriptLogBuffer
	<em>bytes</em><br />
	<a href="directive-dict.html#Default"
	rel="Help"><strong>Default:</strong></a> 1024<br />
	<a href="directive-dict.html#Context"
	rel="Help"><strong>Context:</strong></a> server config<br />
	<a href="directive-dict.html#Status"
	rel="Help"><strong>Status:</strong></a> mod_cgi

	<p>The size of any PUT 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. <!--#include virtual="footer.html" -->
	</p>
	</body>
	</html>