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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "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 Tutorial: Dynamic Content with CGI</title> </head> <!-- Background white, links blue (unvisited), navy (visited), red (active) --> <body bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#000080" alink="#FF0000"> <div align="CENTER"> <img src="../images/sub.gif" alt="[APACHE DOCUMENTATION]" /> <h3>Apache HTTP Server Version 1.3</h3> <p><small><em>Is this the version you want? For more recent versions, check our <a href="/docs/">documentation index</a>.</em></small></p> </div> <h1 align="CENTER">Dynamic Content with CGI</h1> <a id="__index__" name="__index__"></a> <!-- INDEX BEGIN --> <ul> <li><a href="#dynamiccontentwithcgi">Dynamic Content with CGI</a></li> <li> <a href="#configuringapachetopermitcgi">Configuring Apache to permit CGI</a> <ul> <li><a href="#scriptalias">ScriptAlias</a></li> <li> <a href="#cgioutsideofscriptaliasdirectories">CGI outside of ScriptAlias directories</a> <ul> <li><a href="#explicitlyusingoptionstopermitcgiexecution">Explicitly using Options to permit CGI execution</a></li> <li><a href="#htaccessfiles">.htaccess files</a></li> </ul> </li> </ul> </li> <li> <a href="#writingacgiprogram">Writing a CGI program</a> <ul> <li><a href="#yourfirstcgiprogram">Your first CGI program</a></li> </ul> </li> <li> <a href="#butitsstillnotworking">But it's still not working!</a> <ul> <li><a href="#filepermissions">File permissions</a></li> <li><a href="#pathinformation">Path information</a></li> <li><a href="#syntaxerrors">Syntax errors</a></li> <li><a href="#errorlogs">Error logs</a></li> </ul> </li> <li> <a href="#whatsgoingonbehindthescenes">What's going on behind the scenes?</a> <ul> <li><a href="#environmentvariables">Environment variables</a></li> <li><a href="#stdinandstdout">STDIN and STDOUT</a></li> </ul> </li> <li><a href="#cgimoduleslibraries">CGI modules/libraries</a></li> <li><a href="#formoreinformation">For more information</a></li> </ul> <!-- INDEX END --> <hr /> <h2><a id="dynamiccontentwithcgi" name="dynamiccontentwithcgi">Dynamic Content with CGI</a></h2> <table border="1"> <tr> <td valign="top"><strong>Related Modules</strong><br /> <br /> <a href="../mod/mod_alias.html">mod_alias</a><br /> <a href="../mod/mod_cgi.html">mod_cgi</a><br /> </td> <td valign="top"><strong>Related Directives</strong><br /> <br /> <a href="../mod/mod_mime.html#addhandler">AddHandler</a><br /> <a href="../mod/core.html#options">Options</a><br /> <a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a><br /> </td> </tr> </table> <p>The CGI (Common Gateway Interface) defines a way for a web server to interact with external content-generating programs, which are often referred to as CGI programs or CGI scripts. It is the simplest, and most common, way to put dynamic content on your web site. This document will be an introduction to setting up CGI on your Apache web server, and getting started writing CGI programs.</p> <hr /> <h2><a id="configuringapachetopermitcgi" name="configuringapachetopermitcgi">Configuring Apache to permit CGI</a></h2> <p>In order to get your CGI programs to work properly, you'll need to have Apache configured to permit CGI execution. There are several ways to do this.</p> <h3><a id="scriptalias" name="scriptalias">ScriptAlias</a></h3> <p>The <code>ScriptAlias</code> directive tells Apache that a particular directory is set aside for CGI programs. Apache will assume that every file in this directory is a CGI program, and will attempt to execute it, when that particular resource is requested by a client.</p> <p>The <code>ScriptAlias</code> directive looks like:</p><pre> ScriptAlias /cgi-bin/ /usr/local/apache/cgi-bin/</pre> <p>The example shown is from your default <code>httpd.conf</code> configuration file, if you installed Apache in the default location. The <code>ScriptAlias</code> directive is much like the <code>Alias</code> directive, which defines a URL prefix that is to mapped to a particular directory. <code>Alias</code> and <code>ScriptAlias</code> are usually used for directories that are outside of the <code>DocumentRoot</code> directory. The difference between <code>Alias</code> and <code>ScriptAlias</code> is that <code>ScriptAlias</code> has the added meaning that everything under that URL prefix will be considered a CGI program. So, the example above tells Apache that any request for a resource beginning with <code>/cgi-bin/</code> should be served from the directory <code>/usr/local/apache/cgi-bin/</code>, and should be treated as a CGI program.</p> <p>For example, if the URL <code>http://www.example.com/cgi-bin/test.pl</code> is requested, Apache will attempt to execute the file <code>/usr/local/apache/cgi-bin/test.pl</code> and return the output. Of course, the file will have to exist, and be executable, and return output in a particular way, or Apache will return an error message.</p> <h3><a id="cgioutsideofscriptaliasdirectories" name="cgioutsideofscriptaliasdirectories">CGI outside of ScriptAlias directories</a></h3> <p>CGI programs are often restricted to <code>ScriptAlias</code>'ed directories for security reasons. In this way, administrators can tightly control who is allowed to use CGI programs. However, if the proper security precautions are taken, there is no reason why CGI programs cannot be run from arbitrary directories. For example, you may wish to let users have web content in their home directories with the <code>UserDir</code> directive. If they want to have their own CGI programs, but don't have access to the main <code>cgi-bin</code> directory, they will need to be able to run CGI programs elsewhere.</p> <h3><a id="explicitlyusingoptionstopermitcgiexecution" name="explicitlyusingoptionstopermitcgiexecution">Explicitly using Options to permit CGI execution</a></h3> <p>You could explicitly use the <code>Options</code> directive, inside your main server configuration file, to specify that CGI execution was permitted in a particular directory:</p><pre> <Directory /usr/local/apache/htdocs/somedir> Options +ExecCGI </Directory></pre> <p>The above directive tells Apache to permit the execution of CGI files. You will also need to tell the server what files are CGI files. The following <code>AddHandler</code> directive tells the server to treat all files with the <code>cgi</code> or <code>pl</code> extension as CGI programs:</p><pre> AddHandler cgi-script cgi pl</pre> <h3><a id="htaccessfiles" name="htaccessfiles">.htaccess files</a></h3> <p>A <code>.htaccess</code> file is a way to set configuration directives on a per-directory basis. When Apache serves a resource, it looks in the directory from which it is serving a file for a file called <code>.htaccess</code>, and, if it finds it, it will apply directives found therein. <code>.htaccess</code> files can be permitted with the <code>AllowOverride</code> directive, which specifies what types of directives can appear in these files, or if they are not allowed at all. To permit the directive we will need for this purpose, the following configuration will be needed in your main server configuration:</p><pre> AllowOverride Options</pre> <p>In the <code>.htaccess</code> file, you'll need the following directive:</p><pre> Options +ExecCGI</pre> <p>which tells Apache that execution of CGI programs is permitted in this directory.</p> <hr /> <h2><a id="writingacgiprogram" name="writingacgiprogram">Writing a CGI program</a></h2> <p>There are two main differences between ``regular'' programming, and CGI programming.</p> <p>First, all output from your CGI program must be preceded by a MIME-type header. This is HTTP header that tells the client what sort of content it is receiving. Most of the time, this will look like:</p><pre> Content-type: text/html</pre> <p>Secondly, your output needs to be in HTML, or some other format that a browser will be able to display. Most of the time, this will be HTML, but occasionally you might write a CGI program that outputs a gif image, or other non-HTML content.</p> <p>Apart from those two things, writing a CGI program will look a lot like any other program that you might write.</p> <h3><a id="yourfirstcgiprogram" name="yourfirstcgiprogram">Your first CGI program</a></h3> <p>The following is an example CGI program that prints one line to your browser. Type in the following, save it to a file called <code>first.pl</code>, and put it in your <code>cgi-bin</code> directory.</p><pre> #!/usr/bin/perl print "Content-type: text/html\r\n\r\n"; print "Hello, World.";</pre> <p>Even if you are not familiar with Perl, you should be able to see what is happening here. The first line tells Apache (or whatever shell you happen to be running under) that this program can be executed by feeding the file to the interpreter found at the location <code>/usr/bin/perl</code>. The second line prints the content-type declaration we talked about,⌨️ 快捷键说明
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