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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: Introduction to Server Side Includes</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">Apache Tutorial: Introduction to Server Side Includes</h1> <a id="__index__" name="__index__"></a> <!-- INDEX BEGIN --> <ul> <li><a href="#apachetutorial:introductiontoserversideincludes">Apache Tutorial: Introduction to Server Side Includes</a></li> <li><a href="#whataressi">What are SSI?</a></li> <li><a href="#configuringyourservertopermitssi">Configuring your server to permit SSI</a></li> <li> <a href="#basicssidirectives">Basic SSI directives</a> <ul> <li><a href="#today'sdate">Today's date</a></li> <li><a href="#modificationdateofthefile">Modification date of the file</a></li> <li><a href="#includingtheresultsofacgiprogram">Including the results of a CGI program</a></li> </ul> </li> <li> <a href="#additionalexamples">Additional examples</a> <ul> <li><a href="#whenwasthisdocumentmodified">When was this document modified?</a></li> <li><a href="#includingastandardfooter">Including a standard footer</a></li> <li><a href="#whatelsecaniconfig">What else can I config?</a></li> <li><a href="#executingcommands">Executing commands</a></li> </ul> </li> <li> <a href="#advancedssitechniques">Advanced SSI techniques</a> <ul> <li><a href="#settingvariables">Setting variables</a></li> <li><a href="#conditionalexpressions">Conditional expressions</a></li> </ul> </li> <li><a href="#conclusion">Conclusion</a></li> </ul> <!-- INDEX END --> <hr /> <h2><a id="apachetutorial:introductiontoserversideincludes" name="apachetutorial:introductiontoserversideincludes">Apache Tutorial: Introduction to Server Side Includes</a></h2> <table border="1"> <tr> <td valign="top"><strong>Related Modules</strong><br /> <br /> <a href="../mod/mod_include.html">mod_include</a><br /> <a href="../mod/mod_cgi.html">mod_cgi</a><br /> <a href="../mod/mod_expires.html">mod_expires</a><br /> </td> <td valign="top"><strong>Related Directives</strong><br /> <br /> <a href="../mod/core.html#options">Options</a><br /> <a href="../mod/mod_include.html#xbithack">XBitHack</a><br /> <a href="../mod/mod_mime.html#addtype">AddType</a><br /> <a href="../mod/mod_mime.html#addhandler">AddHandler</a><br /> <a href="../mod/mod_setenvif.html#browsermatchnocase">BrowserMatchNoCase</a><br /> </td> </tr> </table> <p>This article deals with Server Side Includes, usually called simply SSI. In this article, I'll talk about configuring your server to permit SSI, and introduce some basic SSI techniques for adding dynamic content to your existing HTML pages.</p> <p>In the latter part of the article, we'll talk about some of the somewhat more advanced things that can be done with SSI, such as conditional statements in your SSI directives.</p> <hr /> <h2><a id="whataressi" name="whataressi">What are SSI?</a></h2> <p>SSI (Server Side Includes) are directives that are placed in HTML pages, and evaluated on the server while the pages are being served. They let you add dynamically generated content to an existing HTML page, without having to serve the entire page via a CGI program, or other dynamic technology.</p> <p>The decision of when to use SSI, and when to have your page entirely generated by some program, is usually a matter of how much of the page is static, and how much needs to be recalculated every time the page is served. SSI is a great way to add small pieces of information, such as the current time. But if a majority of your page is being generated at the time that it is served, you need to look for some other solution.</p> <hr /> <h2><a id="configuringyourservertopermitssi" name="configuringyourservertopermitssi">Configuring your server to permit SSI</a></h2> <p>To permit SSI on your server, you must have <a href="../mod/mod_include.html">mod_include</a> installed and enabled. Additionally, you must have the following directive either in your <code>httpd.conf</code> file, or in a <code>.htaccess</code> file:</p><pre> Options +Includes</pre> <p>This tells Apache that you want to permit files to be parsed for SSI directives. Note that most configurations contain multiple <a href="../mod/core.html#options">Options</a> directives that can override each other. You will probably need to apply the <code>Options</code> to the specific directory where you want SSI enabled in order to assure that it gets evaluated last.</p> <p>Not just any file is parsed for SSI directives. You have to tell Apache which files should be parsed. There are two ways to do this. You can tell Apache to parse any file with a particular file extension, such as <code>.shtml</code>, with the following directives:</p><pre> AddType text/html .shtml AddHandler server-parsed .shtml</pre> <p>One disadvantage to this approach is that if you wanted to add SSI directives to an existing page, you would have to change the name of that page, and all links to that page, in order to give it a <code>.shtml</code> extension, so that those directives would be executed.</p> <p>The other method is to use the <code>XBitHack</code> directive:</p><pre> XBitHack on</pre> <p><code>XBitHack</code> tells Apache to parse files for SSI directives if they have the execute bit set. So, to add SSI directives to an existing page, rather than having to change the file name, you would just need to make the file executable using <code>chmod</code>.</p><pre> chmod +x pagename.html</pre> <p>A brief comment about what not to do. You'll occasionally see people recommending that you just tell Apache to parse all <code>.html</code> files for SSI, so that you don't have to mess with <code>.shtml</code> file names. These folks have perhaps not heard about <code>XBitHack</code>. The thing to keep in mind is that, by doing this, you're requiring that Apache read through every single file that it sends out to clients, even if they don't contain any SSI directives. This can slow things down quite a bit, and is not a good idea.</p> <p>Of course, on Windows, there is no such thing as an execute bit to set, so that limits your options a little.</p> <p>In its default configuration, Apache does not send the last modified date or content length HTTP headers on SSI pages, because these values are difficult to calculate for dynamic content. This can prevent your document from being cached, and result in slower perceived client performance. There are two ways to solve this:</p> <ol> <li>Use the <code>XBitHack Full</code> configuration. This tells Apache to determine the last modified date by looking only at the date of the originally requested file, ignoring the modification date of any included files.</li> <li>Use the directives provided by <a href="../mod/mod_expires.html">mod_expires</a> to set an explicit expiration time on your files, thereby letting browsers and proxies know that it is acceptable to cache them.</li> </ol> <hr /> <h2><a id="basicssidirectives" name="basicssidirectives">Basic SSI directives</a></h2> <p>SSI directives have the following syntax:</p><pre> <!--#element attribute=value attribute=value ... --></pre> <p>It is formatted like an HTML comment, so if you don't have SSI correctly enabled, the browser will ignore it, but it will still be visible in the HTML source. If you have SSI correctly configured, the directive will be replaced with its results.</p> <p>The element can be one of a number of things, and we'll talk some more about most of these in the next installment of this series. For now, here are some examples of what you can do with SSI</p> <h3><a id="today'sdate" name="today'sdate">Today's date</a></h3><pre> <!--#echo var="DATE_LOCAL" --></pre> <p>The <code>echo</code> element just spits out the value of a variable. There are a number of standard variables, which include the whole set of environment variables that are available to CGI programs. Also, you can define your own variables with the <code>set</code> element.</p> <p>If you don't like the format in which the date gets printed, you can use the <code>config</code> element, with a <code>timefmt</code> attribute, to modify that formatting.</p><pre> <!--#config timefmt="%A %B %d, %Y" --> Today is <!--#echo var="DATE_LOCAL" --></pre> <h3><a id="modificationdateofthefile" name="modificationdateofthefile">Modification date of the file</a></h3><pre> This document last modified <!--#flastmod file="index.html" --></pre> <p>This element is also subject to <code>timefmt</code> format configurations.</p>⌨️ 快捷键说明
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