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			502 lines
		
	
	
		
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<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
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              This file is generated from xml source: DO NOT EDIT
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      -->
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<title>Apache Tutorial: Dynamic Content with CGI - Apache HTTP Server</title>
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<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
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<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
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<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" />
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<link href="../images/favicon.ico" rel="shortcut icon" /></head>
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<body id="manual-page"><div id="page-header">
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						|
<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
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<p class="apache">Apache HTTP Server Version 2.1</p>
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<img alt="" src="../images/feather.gif" /></div>
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<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
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<div id="path">
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<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs-project/">Documentation</a> > <a href="../">Version 2.1</a> > <a href="./">How-To / Tutorials</a></div><div id="page-content"><div id="preamble"><h1>Apache Tutorial: Dynamic Content with CGI</h1>
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<div class="toplang">
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<p><span>Available Languages: </span><a href="../en/howto/cgi.html" title="English"> en </a> |
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<a href="../ja/howto/cgi.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
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</div>
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</div>
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<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#intro">Introduction</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#configuring">Configuring Apache to permit CGI</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#writing">Writing a CGI program</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#troubleshoot">But it's still not working!</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#behindscenes">What's going on behind the scenes?</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#libraries">CGI modules/libraries</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#moreinfo">For more information</a></li>
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</ul></div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="section">
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<h2><a name="intro" id="intro">Introduction</a></h2>
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						|
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    <table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code></li><li><code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code></li></ul></td><td><ul><li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li><li><code class="directive"><a href="../mod/core.html#options">Options</a></code></li><li><code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code></li></ul></td></tr></table>
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    <p>The CGI (Common Gateway Interface) defines a way for a web
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    server to interact with external content-generating programs,
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    which are often referred to as CGI programs or CGI scripts. It
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    is the simplest, and most common, way to put dynamic content on
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    your web site. This document will be an introduction to setting
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    up CGI on your Apache web server, and getting started writing
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    CGI programs.</p>
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  </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="section">
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<h2><a name="configuring" id="configuring">Configuring Apache to permit CGI</a></h2>
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    <p>In order to get your CGI programs to work properly, you'll
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    need to have Apache configured to permit CGI execution. There
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    are several ways to do this.</p>
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    <h3><a name="scriptalias" id="scriptalias">ScriptAlias</a></h3>
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						|
      
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      <p>The 
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      <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>
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      directive tells Apache that a particular directory is set
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      aside for CGI programs. Apache will assume that every file in
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      this directory is a CGI program, and will attempt to execute
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      it, when that particular resource is requested by a
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      client.</p>
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						|
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      <p>The <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>
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      directive looks like:</p>
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						|
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      <div class="example"><p><code>
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        ScriptAlias /cgi-bin/ /usr/local/apache/cgi-bin/
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      </code></p></div>
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      <p>The example shown is from your default <code>httpd.conf</code>
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      configuration file, if you installed Apache in the default
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      location. The <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>
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      directive is much like the <code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code> directive, which defines a URL prefix that
 | 
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      is to mapped to a particular directory. <code class="directive">Alias</code>
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      and <code class="directive">ScriptAlias</code> are usually used for
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      directories that are outside of the <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code> directory. The difference between
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      <code class="directive">Alias</code> and <code class="directive">ScriptAlias</code>
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      is that <code class="directive">ScriptAlias</code> has the added meaning
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      that everything under that URL prefix will be considered a CGI
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      program. So, the example above tells Apache that any request for a
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      resource beginning with <code>/cgi-bin/</code> should be served from
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      the directory  <code>/usr/local/apache/cgi-bin/</code>, and should be
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      treated as a CGI program.</p>
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      <p>For example, if the URL
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      <code>http://www.example.com/cgi-bin/test.pl</code>
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      is requested, Apache will attempt to execute the file 
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      <code>/usr/local/apache/cgi-bin/test.pl</code>
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      and return the output. Of course, the file will have to
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      exist, and be executable, and return output in a particular
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      way, or Apache will return an error message.</p>
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    <h3><a name="nonscriptalias" id="nonscriptalias">CGI outside of ScriptAlias directories</a></h3>
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      <p>CGI programs are often restricted to <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories for security reasons.
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      In this way, administrators can tightly control who is allowed to
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      use CGI programs. However, if the proper security precautions are
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      taken, there is no reason why CGI programs cannot be run from
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      arbitrary directories. For example, you may wish to let users
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      have web content in their home directories with the 
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      <code class="directive"><a href="../mod/mod_userdir.html#userdir">UserDir</a></code> directive.
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      If they want to have their own CGI programs, but don't have access to
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      the main <code>cgi-bin</code> directory, they will need to be able to
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      run CGI programs elsewhere.</p>
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    <h3><a name="options" id="options">Explicitly using Options to permit CGI execution</a></h3>
 | 
						|
      
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      <p>You could explicitly use the <code class="directive"><a href="../mod/core.html#options">Options</a></code> directive, inside your main server configuration
 | 
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      file, to specify that CGI execution was permitted in a particular
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      directory:</p>
 | 
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 | 
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      <div class="example"><p><code>
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        <Directory /usr/local/apache/htdocs/somedir><br />
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        <span class="indent">
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          Options +ExecCGI<br />
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        </span>
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        </Directory>
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      </code></p></div>
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      <p>The above directive tells Apache to permit the execution
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						|
      of CGI files. You will also need to tell the server what
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      files are CGI files. The following <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> directive tells the server to treat all
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      files with the <code>cgi</code> or <code>pl</code> extension as CGI
 | 
						|
      programs:</p>
 | 
						|
 | 
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      <div class="example"><p><code>
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        AddHandler cgi-script cgi pl
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						|
      </code></p></div>
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    <h3><a name="htaccess" id="htaccess">.htaccess files</a></h3>
 | 
						|
      
 | 
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      <p>A <a href="htaccess.html"><code>.htaccess</code> file</a> is a way
 | 
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      to set configuration directives on a per-directory basis. When Apache
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      serves a resource, it looks in the directory from which it is serving
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						|
      a file for a file called <code>.htaccess</code>, and, if it 
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      finds it, it will apply directives found therein.  
 | 
						|
      
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      <code>.htaccess</code> files can be permitted with the 
 | 
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      <code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code> directive,
 | 
						|
      which specifies what types of directives can
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      appear in these files, or if they are not allowed at all. To
 | 
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      permit the directive we will need for this purpose, the
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      following configuration will be needed in your main server
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      configuration:</p>
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      <div class="example"><p><code>
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        AllowOverride Options
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      </code></p></div>
 | 
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      <p>In the <code>.htaccess</code> file, you'll need the 
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      following directive:</p>
 | 
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 | 
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      <div class="example"><p><code>
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        Options +ExecCGI
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      </code></p></div>
 | 
						|
 | 
						|
      <p>which tells Apache that execution of CGI programs is
 | 
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      permitted in this directory.</p>
 | 
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  </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | 
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<div class="section">
 | 
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<h2><a name="writing" id="writing">Writing a CGI program</a></h2>
 | 
						|
    
 | 
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 | 
						|
    <p>There are two main differences between ``regular''
 | 
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    programming, and CGI programming.</p>
 | 
						|
 | 
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    <p>First, all output from your CGI program must be preceded by
 | 
						|
    a MIME-type header. This is HTTP header that tells the client
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						|
    what sort of content it is receiving. Most of the time, this
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						|
    will look like:</p>
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						|
    <div class="example"><p><code>
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      Content-type: text/html
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						|
    </code></p></div>
 | 
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 | 
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    <p>Secondly, your output needs to be in HTML, or some other
 | 
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    format that a browser will be able to display. Most of the
 | 
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    time, this will be HTML, but occasionally you might write a CGI
 | 
						|
    program that outputs a gif image, or other non-HTML
 | 
						|
    content.</p>
 | 
						|
 | 
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    <p>Apart from those two things, writing a CGI program will look
 | 
						|
    a lot like any other program that you might write.</p>
 | 
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 | 
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    <h3><a name="firstcgi" id="firstcgi">Your first CGI program</a></h3>
 | 
						|
      
 | 
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 | 
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      <p>The following is an example CGI program that prints one
 | 
						|
      line to your browser. Type in the following, save it to a
 | 
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      file called <code>first.pl</code>, and put it in your 
 | 
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      <code>cgi-bin</code> directory.</p>
 | 
						|
 | 
						|
      <div class="example"><p><code>
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        #!/usr/bin/perl<br />
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        print "Content-type: text/html\n\n";<br />
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        print "Hello, World.";
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      </code></p></div>
 | 
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 | 
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      <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
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      program can be executed by feeding the file to the
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      interpreter found at the location <code>/usr/bin/perl</code>.
 | 
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      The second line prints the content-type declaration we
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      talked about, followed by two carriage-return newline pairs.
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      This puts a blank line after the header, to indicate the end
 | 
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      of the HTTP headers, and the beginning of the body. The third
 | 
						|
      line prints the string "Hello, World.". And that's the end
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      of it.</p>
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      <p>If you open your favorite browser and tell it to get the
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      address</p>
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 | 
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      <div class="example"><p><code>
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        http://www.example.com/cgi-bin/first.pl
 | 
						|
      </code></p></div>
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						|
 | 
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      <p>or wherever you put your file, you will see the one line 
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      <code>Hello, World.</code> appear in your browser window.
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      It's not very exciting, but once you get that working, you'll
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      have a good chance of getting just about anything working.</p>
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  </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | 
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<div class="section">
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<h2><a name="troubleshoot" id="troubleshoot">But it's still not working!</a></h2>
 | 
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 | 
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    <p>There are four basic things that you may see in your browser
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    when you try to access your CGI program from the web:</p>
 | 
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    <dl>
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      <dt>The output of your CGI program</dt>
 | 
						|
      <dd>Great! That means everything worked fine.</dd>
 | 
						|
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						|
      <dt>The source code of your CGI program or a "POST Method Not
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						|
      Allowed" message</dt>
 | 
						|
      <dd>That means that you have not properly configured Apache
 | 
						|
      to process your CGI program. Reread the section on 
 | 
						|
      <a href="#configuringapachetopermitcgi">configuring
 | 
						|
      Apache</a> and try to find what you missed.</dd>
 | 
						|
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						|
      <dt>A message starting with "Forbidden"</dt>
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      <dd>That means that there is a permissions problem. Check the
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      <a href="#errorlogs">Apache error log</a> and the section below on
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						|
      <a href="#permissions">file permissions</a>.</dd>
 | 
						|
 | 
						|
      <dt>A message saying "Internal Server Error"</dt>
 | 
						|
      <dd>If you check the 
 | 
						|
      <a href="#errorlogs">Apache error log</a>, you will probably
 | 
						|
      find that it says "Premature end of
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						|
      script headers", possibly along with an error message
 | 
						|
      generated by your CGI program. In this case, you will want to
 | 
						|
      check each of the below sections to see what might be
 | 
						|
      preventing your CGI program from emitting the proper HTTP
 | 
						|
      headers.</dd>
 | 
						|
    </dl>
 | 
						|
 | 
						|
    <h3><a name="permissions" id="permissions">File permissions</a></h3>
 | 
						|
      
 | 
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 | 
						|
      <p>Remember that the server does not run as you. That is,
 | 
						|
      when the server starts up, it is running with the permissions
 | 
						|
      of an unprivileged user - usually <code>nobody</code>, or
 | 
						|
      <code>www</code> - and so it will need extra permissions to
 | 
						|
      execute files that are owned by you. Usually, the way to give
 | 
						|
      a file sufficient permissions to be executed by <code>nobody</code>
 | 
						|
      is to give everyone execute permission on the file:</p>
 | 
						|
 | 
						|
      <div class="example"><p><code>
 | 
						|
        chmod a+x first.pl
 | 
						|
      </code></p></div>
 | 
						|
 | 
						|
      <p>Also, if your program reads from, or writes to, any other
 | 
						|
      files, those files will need to have the correct permissions
 | 
						|
      to permit this.</p>
 | 
						|
 | 
						|
      <p>The exception to this is when the server is configured to
 | 
						|
      use <a href="../suexec.html">suexec</a>. This program allows
 | 
						|
      CGI programs to be run under different
 | 
						|
      user permissions, depending on which virtual host or user
 | 
						|
      home directory they are located in. Suexec has very strict
 | 
						|
      permission checking, and any failure in that checking will
 | 
						|
      result in your CGI programs failing with an "Internal Server
 | 
						|
      Error". In this case, you will need to check the suexec log
 | 
						|
      file to see what specific security check is failing.</p>
 | 
						|
    
 | 
						|
 | 
						|
    <h3><a name="pathinformation" id="pathinformation">Path information</a></h3>
 | 
						|
      
 | 
						|
 | 
						|
      <p>When you run a program from your command line, you have
 | 
						|
      certain information that is passed to the shell without you
 | 
						|
      thinking about it. For example, you have a path, which tells
 | 
						|
      the shell where it can look for files that you reference.</p>
 | 
						|
 | 
						|
      <p>When a program runs through the web server as a CGI
 | 
						|
      program, it does not have that path. Any programs that you
 | 
						|
      invoke in your CGI program (like 'sendmail', for example)
 | 
						|
      will need to be specified by a full path, so that the shell
 | 
						|
      can find them when it attempts to execute your CGI
 | 
						|
      program.</p>
 | 
						|
 | 
						|
      <p>A common manifestation of this is the path to the script
 | 
						|
      interpreter (often <code>perl</code>) indicated in the first
 | 
						|
      line of your CGI program, which will look something like:</p>
 | 
						|
 | 
						|
      <div class="example"><p><code>
 | 
						|
        #!/usr/bin/perl
 | 
						|
      </code></p></div>
 | 
						|
 | 
						|
      <p>Make sure that this is in fact the path to the
 | 
						|
      interpreter.</p>
 | 
						|
    
 | 
						|
 | 
						|
    <h3><a name="syntaxerrors" id="syntaxerrors">Syntax errors</a></h3>
 | 
						|
      
 | 
						|
 | 
						|
      <p>Most of the time when a CGI program fails, it's because of
 | 
						|
      a problem with the program itself. This is particularly true
 | 
						|
      once you get the hang of this CGI stuff, and no longer make
 | 
						|
      the above two mistakes. Always attempt to run your program
 | 
						|
      from the command line before you test if via a browser. This
 | 
						|
      will eliminate most of your problems.</p>
 | 
						|
    
 | 
						|
 | 
						|
    <h3><a name="errorlogs" id="errorlogs">Error logs</a></h3>
 | 
						|
      
 | 
						|
 | 
						|
      <p>The error logs are your friend. Anything that goes wrong
 | 
						|
      generates message in the error log. You should always look
 | 
						|
      there first. If the place where you are hosting your web site
 | 
						|
      does not permit you access to the error log, you should
 | 
						|
      probably host your site somewhere else. Learn to read the
 | 
						|
      error logs, and you'll find that almost all of your problems
 | 
						|
      are quickly identified, and quickly solved.</p>
 | 
						|
    
 | 
						|
  </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | 
						|
<div class="section">
 | 
						|
<h2><a name="behindscenes" id="behindscenes">What's going on behind the scenes?</a></h2>
 | 
						|
    
 | 
						|
 | 
						|
    <p>As you become more advanced in CGI programming, it will
 | 
						|
    become useful to understand more about what's happening behind
 | 
						|
    the scenes. Specifically, how the browser and server
 | 
						|
    communicate with one another. Because although it's all very
 | 
						|
    well to write a program that prints "Hello, World.", it's not
 | 
						|
    particularly useful.</p>
 | 
						|
 | 
						|
    <h3><a name="env" id="env">Environment variables</a></h3>
 | 
						|
      
 | 
						|
 | 
						|
      <p>Environment variables are values that float around you as
 | 
						|
      you use your computer. They are useful things like your path
 | 
						|
      (where the computer searches for a the actual file
 | 
						|
      implementing a command when you type it), your username, your
 | 
						|
      terminal type, and so on. For a full list of your normal,
 | 
						|
      every day environment variables, type 
 | 
						|
      <code>env</code> at a command prompt.</p>
 | 
						|
 | 
						|
      <p>During the CGI transaction, the server and the browser
 | 
						|
      also set environment variables, so that they can communicate
 | 
						|
      with one another. These are things like the browser type
 | 
						|
      (Netscape, IE, Lynx), the server type (Apache, IIS, WebSite),
 | 
						|
      the name of the CGI program that is being run, and so on.</p>
 | 
						|
 | 
						|
      <p>These variables are available to the CGI programmer, and
 | 
						|
      are half of the story of the client-server communication. The
 | 
						|
      complete list of required variables is at 
 | 
						|
      <a href="http://hoohoo.ncsa.uiuc.edu/cgi/env.html">http://hoohoo.ncsa.uiuc.edu/cgi/env.html</a>.</p>
 | 
						|
 | 
						|
      <p>This simple Perl CGI program will display all of the
 | 
						|
      environment variables that are being passed around. Two
 | 
						|
      similar programs are included in the 
 | 
						|
      <code>cgi-bin</code>
 | 
						|
 | 
						|
      directory of the Apache distribution. Note that some
 | 
						|
      variables are required, while others are optional, so you may
 | 
						|
      see some variables listed that were not in the official list.
 | 
						|
      In addition, Apache provides many different ways for you to 
 | 
						|
      <a href="../env.html">add your own environment variables</a>
 | 
						|
      to the basic ones provided by default.</p>
 | 
						|
 | 
						|
      <div class="example"><p><code>
 | 
						|
        #!/usr/bin/perl<br />
 | 
						|
        print "Content-type: text/html\n\n";<br />
 | 
						|
        foreach $key (keys %ENV) {<br />
 | 
						|
        <span class="indent">
 | 
						|
          print "$key --> $ENV{$key}<br>";<br />
 | 
						|
        </span>
 | 
						|
        }
 | 
						|
      </code></p></div>
 | 
						|
    
 | 
						|
 | 
						|
    <h3><a name="stdin" id="stdin">STDIN and STDOUT</a></h3>
 | 
						|
      
 | 
						|
 | 
						|
      <p>Other communication between the server and the client
 | 
						|
      happens over standard input (<code>STDIN</code>) and standard
 | 
						|
      output (<code>STDOUT</code>). In normal everyday context, 
 | 
						|
      <code>STDIN</code> means the keyboard, or a file that a 
 | 
						|
      program is given to act on, and <code>STDOUT</code>
 | 
						|
      usually means the console or screen.</p> 
 | 
						|
 | 
						|
      <p>When you <code>POST</code> a web form to a CGI program,
 | 
						|
      the data in that form is bundled up into a special format
 | 
						|
      and gets delivered to your CGI program over <code>STDIN</code>.
 | 
						|
      The program then can process that data as though it was
 | 
						|
      coming in from the keyboard, or from a file</p>
 | 
						|
 | 
						|
      <p>The "special format" is very simple. A field name and
 | 
						|
      its value are joined together with an equals (=) sign, and
 | 
						|
      pairs of values are joined together with an ampersand
 | 
						|
      (&). Inconvenient characters like spaces, ampersands, and
 | 
						|
      equals signs, are converted into their hex equivalent so that
 | 
						|
      they don't gum up the works. The whole data string might look
 | 
						|
      something like:</p>
 | 
						|
 | 
						|
      <div class="example"><p><code>
 | 
						|
        name=Rich%20Bowen&city=Lexington&state=KY&sidekick=Squirrel%20Monkey
 | 
						|
      </code></p></div>
 | 
						|
 | 
						|
      <p>You'll sometimes also see this type of string appended to
 | 
						|
      the a URL. When that is done, the server puts that string
 | 
						|
      into the environment variable called 
 | 
						|
      <code>QUERY_STRING</code>. That's called a <code>GET</code>
 | 
						|
      request. Your HTML form specifies whether a <code>GET</code>
 | 
						|
      or a <code>POST</code> is used to deliver the data, by setting the 
 | 
						|
      <code>METHOD</code> attribute in the <code>FORM</code> tag.</p>
 | 
						|
 | 
						|
      <p>Your program is then responsible for splitting that string
 | 
						|
      up into useful information. Fortunately, there are libraries
 | 
						|
      and modules available to help you process this data, as well
 | 
						|
      as handle other of the aspects of your CGI program.</p>
 | 
						|
    
 | 
						|
  </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | 
						|
<div class="section">
 | 
						|
<h2><a name="libraries" id="libraries">CGI modules/libraries</a></h2>
 | 
						|
    
 | 
						|
 | 
						|
    <p>When you write CGI programs, you should consider using a
 | 
						|
    code library, or module, to do most of the grunt work for you.
 | 
						|
    This leads to fewer errors, and faster development.</p>
 | 
						|
 | 
						|
    <p>If you're writing CGI programs in Perl, modules are
 | 
						|
    available on <a href="http://www.cpan.org/">CPAN</a>. The most
 | 
						|
    popular module for this purpose is <code>CGI.pm</code>. You might
 | 
						|
    also consider <code>CGI::Lite</code>, which implements a minimal
 | 
						|
    set of functionality, which is all you need in most programs.</p>
 | 
						|
 | 
						|
    <p>If you're writing CGI programs in C, there are a variety of
 | 
						|
    options. One of these is the <code>CGIC</code> library, from 
 | 
						|
    <a href="http://www.boutell.com/cgic/">http://www.boutell.com/cgic/</a>.</p>
 | 
						|
  </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 | 
						|
<div class="section">
 | 
						|
<h2><a name="moreinfo" id="moreinfo">For more information</a></h2>
 | 
						|
    
 | 
						|
 | 
						|
    <p>There are a large number of CGI resources on the web. You
 | 
						|
    can discuss CGI problems with other users on the Usenet group
 | 
						|
    <a href="news:comp.infosystems.www.authoring.cgi">comp.infosystems.www.authoring.cgi</a>. And the -servers mailing
 | 
						|
    list from the HTML Writers Guild is a great source of answers
 | 
						|
    to your questions. You can find out more at 
 | 
						|
    <a href="http://www.hwg.org/lists/hwg-servers/">http://www.hwg.org/lists/hwg-servers/</a>.</p>
 | 
						|
 | 
						|
    <p>And, of course, you should probably read the CGI
 | 
						|
    specification, which has all the details on the operation of
 | 
						|
    CGI programs. You can find the original version at the 
 | 
						|
    <a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html">NCSA</a> and there is an updated draft at the 
 | 
						|
    <a href="http://web.golux.com/coar/cgi/">Common Gateway
 | 
						|
    Interface RFC project</a>.</p>
 | 
						|
 | 
						|
    <p>When you post a question about a CGI problem that you're
 | 
						|
    having, whether to a mailing list, or to a newsgroup, make sure
 | 
						|
    you provide enough information about what happened, what you
 | 
						|
    expected to happen, and how what actually happened was
 | 
						|
    different, what server you're running, what language your CGI
 | 
						|
    program was in, and, if possible, the offending code. This will
 | 
						|
    make finding your problem much simpler.</p>
 | 
						|
 | 
						|
    <p>Note that questions about CGI problems should <strong>never</strong>
 | 
						|
    be posted to the Apache bug database unless you are sure you
 | 
						|
    have found a problem in the Apache source code.</p>
 | 
						|
  </div></div>
 | 
						|
<div class="bottomlang">
 | 
						|
<p><span>Available Languages: </span><a href="../en/howto/cgi.html" title="English"> en </a> |
 | 
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<a href="../ja/howto/cgi.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
 | 
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</div><div id="footer">
 | 
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<p class="apache">Maintained by the <a href="http://httpd.apache.org/docs-project/">Apache HTTP Server Documentation Project</a></p>
 | 
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<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div>
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