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git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@99326 13f79535-47bb-0310-9956-ffa450edef68
221 lines
8.8 KiB
XML
221 lines
8.8 KiB
XML
<?xml version="1.0"?>
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<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
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<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
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<modulesynopsis metafile="mod_cgi.xml.meta">
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<name>mod_cgi</name>
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<description>Execution of CGI scripts</description>
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<status>Base</status>
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<sourcefile>mod_cgi.c</sourcefile>
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<identifier>cgi_module</identifier>
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<summary>
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<!-- XXX: Should mention Options ExecCGI
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is the link to howto/cgi not sufficient? -nd
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-->
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<p>Any file that has the mime type
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<code>application/x-httpd-cgi</code> or handler
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<code>cgi-script</code> (Apache 1.1 or later) will be treated
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as a CGI script, and run by the server, with its output being
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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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<directive module="mod_mime">AddType</directive> directive, or by being
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in a <directive module="mod_alias">ScriptAlias</directive>
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directory.</p>
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<p>When the server invokes a CGI script, it will add a variable
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called <code>DOCUMENT_ROOT</code> to the environment. This
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variable will contain the value of the
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<directive module="core">DocumentRoot</directive> configuration
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variable.</p>
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<p>For an introduction to using CGI scripts with Apache, see
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our tutorial on <a href="../howto/cgi.html">Dynamic Content
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With CGI</a>.</p>
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<p>When using a multi-threaded MPM under unix, the module
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<module>mod_cgid</module> should be used in place of
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this module. At the user level, the two modules are essentially
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identical.</p>
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</summary>
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<seealso><directive module="core">AcceptPathInfo</directive></seealso>
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<seealso><directive module="core">Options</directive></seealso>
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<seealso><directive module="mod_alias">ScriptAlias</directive></seealso>
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<seealso><directive module="mod_mime">AddHandler</directive></seealso>
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<seealso><a href="../suexec.html">Running CGI programs under different user IDs</a></seealso>
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<seealso><a href="http://hoohoo.ncsa.uiuc.edu/cgi/">CGI Specification</a></seealso>
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<section id="env"><title>CGI Environment variables</title>
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<p>The server will set the CGI environment variables as described
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in the <a href="http://hoohoo.ncsa.uiuc.edu/cgi/">CGI
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specification</a>, with the following provisions:</p>
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<dl>
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<dt>PATH_INFO</dt>
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<dd>This will not be available if the <directive module="core"
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>AcceptPathInfo</directive> directive is explicitly set to
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<code>off</code>. The default behavior, if <directive
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>AcceptPathInfo</directive> is not given, is that <module
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>mod_cgi</module> will accept path info (trailing <code>
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/more/path/info</code> following the script filename in the URI),
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while the core server will return a 404 NOT FOUND error for requests
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with additional path info. Omitting the <directive
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>AcceptPathInfo</directive> directive has the same effect as setting
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it <code>On</code> for <module>mod_cgi</module> requests.</dd>
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<dt>REMOTE_HOST</dt>
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<dd>This will only be set if <directive module="core"
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>HostnameLookups</directive> is set to <code>on</code> (it
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is off by default), and if a reverse DNS lookup of the accessing
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host's address indeed finds a host name.</dd>
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<dt>REMOTE_IDENT</dt>
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<dd>This will only be set if <directive module="core"
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>IdentityCheck</directive> is set to
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<code>on</code> and the accessing host supports the ident
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protocol. Note that the contents of this variable cannot be
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relied upon because it can easily be faked, and if there is a
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proxy between the client and the server, it is usually
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totally useless.</dd>
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<dt>REMOTE_USER</dt>
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<dd>This will only be set if the CGI script is subject to
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authentication.</dd>
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</dl>
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</section>
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<section id="cgi-debug"><title>CGI Debugging</title>
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<p>Debugging CGI scripts has traditionally been difficult, mainly
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because it has not been possible to study the output (standard
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output and error) for scripts which are failing to run
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properly. These directives, included in Apache 1.2 and later,
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provide more detailed logging of errors when they occur.</p>
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<section><title>CGI Logfile Format</title>
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<p>When configured, the CGI error log logs any CGI which does not
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execute properly. Each CGI script which fails to operate causes
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several lines of information to be logged. The first two lines
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are always of the format:</p>
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<example>
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%% [<var>time</var>] <var>request-line</var><br />
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%% <var>HTTP-status</var> <var>CGI-script-filename</var>
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</example>
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<p>If the error is that CGI script cannot be run, the log file
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will contain an extra two lines:</p>
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<example>
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%%error<br />
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<var>error-message</var>
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</example>
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<p>Alternatively, if the error is the result of the script
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returning incorrect header information (often due to a bug in
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the script), the following information is logged:</p>
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<example>
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%request<br />
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<var>All HTTP request headers received</var><br />
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<var>POST or PUT entity (if any)</var><br />
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%response<br />
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<var>All headers output by the CGI script</var><br />
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%stdout<br />
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<var>CGI standard output</var><br />
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%stderr<br />
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<var>CGI standard error</var><br />
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</example>
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<p>(The %stdout and %stderr parts may be missing if the script did
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not output anything on standard output or standard error).</p>
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</section>
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</section>
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<directivesynopsis>
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<name>ScriptLog</name>
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<description>Location of the CGI script error logfile</description>
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<syntax>ScriptLog <var>file-path</var></syntax>
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<contextlist><context>server config</context>
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<context>virtual host</context></contextlist>
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<modulelist><module>mod_cgi</module><module>mod_cgid</module>
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</modulelist>
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<usage>
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<p>The <directive>ScriptLog</directive> directive sets the CGI
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script error logfile. If no <directive>ScriptLog</directive> is given,
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no error log is created. If given, any CGI errors are logged into the
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filename given as argument. If this is a relative file or path it is
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taken relative to the <directive module="core">ServerRoot</directive>.
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</p>
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<example><title>Example</title>
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ScriptLog logs/cgi_log
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</example>
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<p>This log will be opened as the user the child processes run
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as, <em>i.e.</em> the user specified in the main <directive
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module="mpm_common">User</directive> directive. This means that
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either the directory the script log is in needs to be writable
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by that user or the file needs to be manually created and set
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to be writable by that user. If you place the script log in
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your main logs directory, do <strong>NOT</strong> change the
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directory permissions to make it writable by the user the child
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processes run as.</p>
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<p>Note that script logging is meant to be a debugging feature
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when writing CGI scripts, and is not meant to be activated
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continuously on running servers. It is not optimized for speed
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or efficiency, and may have security problems if used in a
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manner other than that for which it was designed.</p>
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</usage>
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</directivesynopsis>
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<directivesynopsis>
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<name>ScriptLogLength</name>
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<description>Size limit of the CGI script logfile</description>
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<syntax>ScriptLogLength <var>bytes</var></syntax>
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<default>ScriptLogLength 10385760</default>
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<contextlist><context>server config</context>
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<context>virtual host</context></contextlist>
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<modulelist><module>mod_cgi</module><module>mod_cgid</module>
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</modulelist>
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<usage>
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<p><directive>ScriptLogLength</directive> can be used to limit the
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size of the CGI script logfile. Since the logfile logs a lot of
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information per CGI error (all request headers, all script output)
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it can grow to be a big file. To prevent problems due to unbounded
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growth, this directive can be used to set an maximum file-size for
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the CGI logfile. If the file exceeds this size, no more
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information will be written to it.</p>
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</usage>
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</directivesynopsis>
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<directivesynopsis>
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<name>ScriptLogBuffer</name>
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<description>Maximum amount of PUT or POST requests that will be recorded
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in the scriptlog</description>
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<syntax>ScriptLogBuffer <var>bytes</var></syntax>
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<default>ScriptLogBuffer 1024</default>
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<contextlist><context>server config</context>
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<context>virtual host</context></contextlist>
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<modulelist><module>mod_cgi</module><module>mod_cgid</module>
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</modulelist>
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<usage>
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<p>The size of any PUT or POST entity body that is logged to
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the file is limited, to prevent the log file growing too big
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too quickly if large bodies are being received. By default, up
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to 1024 bytes are logged, but this can be changed with this
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directive.</p>
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</usage>
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</directivesynopsis>
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</modulesynopsis>
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