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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:01:30 +0000 |
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| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:01:30 +0000 |
| commit | 6beeb1b708550be0d4a53b272283e17e5e35fe17 (patch) | |
| tree | 1ce8673d4aaa948e5554000101f46536a1e4cc29 /docs/manual/howto/ssi.html.en | |
| parent | Initial commit. (diff) | |
| download | apache2-6beeb1b708550be0d4a53b272283e17e5e35fe17.tar.xz apache2-6beeb1b708550be0d4a53b272283e17e5e35fe17.zip | |
Adding upstream version 2.4.57.upstream/2.4.57
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'docs/manual/howto/ssi.html.en')
| -rw-r--r-- | docs/manual/howto/ssi.html.en | 503 |
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diff --git a/docs/manual/howto/ssi.html.en b/docs/manual/howto/ssi.html.en new file mode 100644 index 0000000..53ea265 --- /dev/null +++ b/docs/manual/howto/ssi.html.en @@ -0,0 +1,503 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head> +<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" /> +<!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>Apache httpd Tutorial: Introduction to Server Side Includes - Apache HTTP Server Version 2.4</title> +<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> +<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> +<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" /> +<script src="../style/scripts/prettify.min.js" type="text/javascript"> +</script> + +<link href="../images/favicon.ico" rel="shortcut icon" /></head> +<body id="manual-page"><div id="page-header"> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> +<p class="apache">Apache HTTP Server Version 2.4</p> +<img alt="" src="../images/feather.png" /></div> +<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div> +<div id="path"> +<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.4</a> > <a href="./">How-To / Tutorials</a></div><div id="page-content"><div id="preamble"><h1>Apache httpd Tutorial: Introduction to Server Side Includes</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="../en/howto/ssi.html" title="English"> en </a> | +<a href="../es/howto/ssi.html" hreflang="es" rel="alternate" title="Español"> es </a> | +<a href="../fr/howto/ssi.html" hreflang="fr" rel="alternate" title="Français"> fr </a> | +<a href="../ja/howto/ssi.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | +<a href="../ko/howto/ssi.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p> +</div> + +<p>Server-side includes provide a means to add dynamic content to +existing HTML documents.</p> +</div> +<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#related">Introduction</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#what">What are SSI?</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#configuring">Configuring your server to permit SSI</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#basic">Basic SSI directives</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#additionalexamples">Additional examples</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#config">What else can I config?</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#exec">Executing commands</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#advanced">Advanced SSI techniques</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#conclusion">Conclusion</a></li> +</ul><h3>See also</h3><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div> +<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="related" id="related">Introduction</a></h2> + <table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="../mod/mod_include.html">mod_include</a></code></li><li><code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code></li><li><code class="module"><a href="../mod/mod_expires.html">mod_expires</a></code></li></ul></td><td><ul><li><code class="directive"><a href="../mod/core.html#options">Options</a></code></li><li><code class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></code></li><li><code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code></li><li><code class="directive"><a href="../mod/core.html#setoutputfilter">SetOutputFilter</a></code></li><li><code class="directive"><a href="../mod/mod_setenvif.html#browsermatchnocase">BrowserMatchNoCase</a></code></li></ul></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> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="what" id="what">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>For example, you might place a directive into an existing HTML + page, such as:</p> + + <div class="example"><p><code> + <!--#echo var="DATE_LOCAL" --> + </code></p></div> + + <p>And, when the page is served, this fragment will be evaluated and replaced with its value:</p> + + <div class="example"><p><code> + Tuesday, 15-Jan-2013 19:28:54 EST + </code></p></div> + + <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 - shown + above. 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> +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="configuring" id="configuring">Configuring your server to permit SSI</a></h2> + + + <p>To permit SSI on your server, you must have the following + directive either in your <code>httpd.conf</code> file, or in a + <code>.htaccess</code> file:</p> +<pre class="prettyprint lang-config">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 <code class="directive"><a href="../mod/core.html#options">Options</a></code> 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 class="prettyprint lang-config">AddType text/html .shtml +AddOutputFilter INCLUDES .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 class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></code> directive:</p> +<pre class="prettyprint lang-config">XBitHack on</pre> + + + <p><code class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></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> +<div class="example"><p><code> + chmod +x pagename.html +</code></p></div> + + <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 class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></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 + <code class="module"><a href="../mod/mod_expires.html">mod_expires</a></code> to set an explicit expiration + time on your files, thereby letting browsers and proxies + know that it is acceptable to cache them.</li> + </ol> +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="basic" id="basic">Basic SSI directives</a></h2> + + <p>SSI directives have the following syntax:</p> +<div class="example"><p><code> + <!--#function attribute=value attribute=value ... --> +</code></p></div> + + <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 function 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 name="todaysdate" id="todaysdate">Today's date</a></h3> + +<div class="example"><p><code> + <!--#echo var="DATE_LOCAL" --> +</code></p></div> + + <p>The <code>echo</code> function 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> function.</p> + + <p>If you don't like the format in which the date gets printed, + you can use the <code>config</code> function, with a + <code>timefmt</code> attribute, to modify that formatting.</p> + +<div class="example"><p><code> + <!--#config timefmt="%A %B %d, %Y" --><br /> + Today is <!--#echo var="DATE_LOCAL" --> +</code></p></div> + + +<h3><a name="lastmodified" id="lastmodified">Modification date of the file</a></h3> + +<div class="example"><p><code> + This document last modified <!--#flastmod file="index.html" --> +</code></p></div> + + <p>This function is also subject to <code>timefmt</code> format + configurations.</p> + + +<h3><a name="cgi" id="cgi">Including the results of a CGI program</a></h3> + + <p>This is one of the more common uses of SSI - to output the + results of a CGI program, such as everybody's favorite, a ``hit + counter.''</p> + +<div class="example"><p><code> + <!--#include virtual="/cgi-bin/counter.pl" --> +</code></p></div> + + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="additionalexamples" id="additionalexamples">Additional examples</a></h2> + + + <p>Following are some specific examples of things you can do in + your HTML documents with SSI.</p> + +<h3><a name="docmodified" id="docmodified">When was this document +modified?</a></h3> + + <p>Earlier, we mentioned that you could use SSI to inform the + user when the document was most recently modified. However, the + actual method for doing that was left somewhat in question. The + following code, placed in your HTML document, will put such a + time stamp on your page. Of course, you will have to have SSI + correctly enabled, as discussed above.</p> +<div class="example"><p><code> + <!--#config timefmt="%A %B %d, %Y" --><br /> + This file last modified <!--#flastmod file="ssi.shtml" --> +</code></p></div> + + <p>Of course, you will need to replace the + <code>ssi.shtml</code> with the actual name of the file that + you're referring to. This can be inconvenient if you're just + looking for a generic piece of code that you can paste into any + file, so you probably want to use the + <code>LAST_MODIFIED</code> variable instead:</p> +<div class="example"><p><code> + <!--#config timefmt="%D" --><br /> + This file last modified <!--#echo var="LAST_MODIFIED" --> +</code></p></div> + + <p>For more details on the <code>timefmt</code> format, go to + your favorite search site and look for <code>strftime</code>. The + syntax is the same.</p> + + +<h3><a name="standard-footer" id="standard-footer">Including a standard footer</a></h3> + + + <p>If you are managing any site that is more than a few pages, + you may find that making changes to all those pages can be a + real pain, particularly if you are trying to maintain some kind + of standard look across all those pages.</p> + + <p>Using an include file for a header and/or a footer can + reduce the burden of these updates. You just have to make one + footer file, and then include it into each page with the + <code>include</code> SSI command. The <code>include</code> + function can determine what file to include with either the + <code>file</code> attribute, or the <code>virtual</code> + attribute. The <code>file</code> attribute is a file path, + <em>relative to the current directory</em>. That means that it + cannot be an absolute file path (starting with /), nor can it + contain ../ as part of that path. The <code>virtual</code> + attribute is probably more useful, and should specify a URL + relative to the document being served. It can start with a /, + but must be on the same server as the file being served.</p> +<div class="example"><p><code> + <!--#include virtual="/footer.html" --> +</code></p></div> + + <p>I'll frequently combine the last two things, putting a + <code>LAST_MODIFIED</code> directive inside a footer file to be + included. SSI directives can be contained in the included file, + and includes can be nested - that is, the included file can + include another file, and so on.</p> + + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="config" id="config">What else can I config?</a></h2> + + + <p>In addition to being able to <code>config</code> the time + format, you can also <code>config</code> two other things.</p> + + <p>Usually, when something goes wrong with your SSI directive, + you get the message</p> +<div class="example"><p><code> + [an error occurred while processing this directive] +</code></p></div> + + <p>If you want to change that message to something else, you + can do so with the <code>errmsg</code> attribute to the + <code>config</code> function:</p> +<div class="example"><p><code> + <!--#config errmsg="[It appears that you don't know how to use SSI]" --> +</code></p></div> + + <p>Hopefully, end users will never see this message, because + you will have resolved all the problems with your SSI + directives before your site goes live. (Right?)</p> + + <p>And you can <code>config</code> the format in which file + sizes are returned with the <code>sizefmt</code> attribute. You + can specify <code>bytes</code> for a full count in bytes, or + <code>abbrev</code> for an abbreviated number in Kb or Mb, as + appropriate.</p> + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="exec" id="exec">Executing commands</a></h2> + + + <p>Here's something else that you can do with the <code>exec</code> + function. You can actually have SSI execute a command using the + shell (<code>/bin/sh</code>, to be precise - or the DOS shell, + if you're on Win32). The following, for example, will give you + a directory listing.</p> +<div class="example"><p><code> + <pre><br /> + <!--#exec cmd="ls" --><br /> + </pre> +</code></p></div> + + <p>or, on Windows</p> +<div class="example"><p><code> + <pre><br /> + <!--#exec cmd="dir" --><br /> + </pre> +</code></p></div> + + <p>You might notice some strange formatting with this directive + on Windows, because the output from <code>dir</code> contains + the string ``<<code>dir</code>>'' in it, which confuses + browsers.</p> + + <p>Note that this feature is exceedingly dangerous, as it will + execute whatever code happens to be embedded in the + <code>exec</code> tag. If you have any situation where users + can edit content on your web pages, such as with a + ``guestbook'', for example, make sure that you have this + feature disabled. You can allow SSI, but not the + <code>exec</code> feature, with the <code>IncludesNOEXEC</code> + argument to the <code>Options</code> directive.</p> + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="advanced" id="advanced">Advanced SSI techniques</a></h2> + + + <p>In addition to spitting out content, Apache SSI gives you + the option of setting variables, and using those variables in + comparisons and conditionals.</p> + +<h3><a name="variables" id="variables">Setting variables</a></h3> + + <p>Using the <code>set</code> directive, you can set variables + for later use. We'll need this later in the discussion, so + we'll talk about it here. The syntax of this is as follows:</p> +<div class="example"><p><code> + <!--#set var="name" value="Rich" --> +</code></p></div> + + <p>In addition to merely setting values literally like that, you + can use any other variable, including <a href="../env.html">environment variables</a> or the variables + discussed above (like <code>LAST_MODIFIED</code>, for example) to + give values to your variables. You will specify that something is + a variable, rather than a literal string, by using the dollar sign + ($) before the name of the variable.</p> + + <div class="example"><p><code> <!--#set var="modified" value="$LAST_MODIFIED" --> + </code></p></div> + + <p>To put a literal dollar sign into the value of your + variable, you need to escape the dollar sign with a + backslash.</p> +<div class="example"><p><code> + <!--#set var="cost" value="\$100" --> +</code></p></div> + + <p>Finally, if you want to put a variable in the midst of a + longer string, and there's a chance that the name of the + variable will run up against some other characters, and thus be + confused with those characters, you can place the name of the + variable in braces, to remove this confusion. (It's hard to + come up with a really good example of this, but hopefully + you'll get the point.)</p> +<div class="example"><p><code> + <!--#set var="date" value="${DATE_LOCAL}_${DATE_GMT}" --> +</code></p></div> + + +<h3><a name="conditional" id="conditional">Conditional expressions</a></h3> + + + <p>Now that we have variables, and are able to set and compare + their values, we can use them to express conditionals. This + lets SSI be a tiny programming language of sorts. + <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> provides an <code>if</code>, + <code>elif</code>, <code>else</code>, <code>endif</code> + structure for building conditional statements. This allows you + to effectively generate multiple logical pages out of one + actual page.</p> + + <p>The structure of this conditional construct is:</p> +<div class="example"><p><code> + <!--#if expr="test_condition" --><br /> + <!--#elif expr="test_condition" --><br /> + <!--#else --><br /> + <!--#endif --> +</code></p></div> + + <p>A <em>test_condition</em> can be any sort of logical + comparison - either comparing values to one another, or testing + the ``truth'' of a particular value. (A given string is true if + it is nonempty.) For a full list of the comparison operators + available to you, see the <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> + documentation.</p> + + <p>For example, if you wish to customize the text on your web page + based on the time of day, you could use the following recipe, placed + in the HTML page:</p> + + <div class="example"><p><code> + Good + <!--#if expr="%{TIME_HOUR} <12" --><br /> + morning!<br /> + <!--#else --><br /> + afternoon!<br /> + <!--#endif --><br /> + </code></p></div> + + <p>Any other variable (either ones that you define, or normal + environment variables) can be used in conditional statements. + See <a href="../expr.html">Expressions in Apache HTTP Server</a> for + more information on the expression evaluation engine.</p> + + <p>With Apache's ability to set environment variables with the + <code>SetEnvIf</code> directives, and other related directives, + this functionality can let you do a wide variety of dynamic content + on the server side without resorting a full web application.</p> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="conclusion" id="conclusion">Conclusion</a></h2> + + <p>SSI is certainly not a replacement for CGI, or other + technologies used for generating dynamic web pages. But it is a + great way to add small amounts of dynamic content to pages, + without doing a lot of extra work.</p> +</div></div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="../en/howto/ssi.html" title="English"> en </a> | +<a href="../es/howto/ssi.html" hreflang="es" rel="alternate" title="Español"> es </a> | +<a href="../fr/howto/ssi.html" hreflang="fr" rel="alternate" title="Français"> fr </a> | +<a href="../ja/howto/ssi.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | +<a href="../ko/howto/ssi.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p> +</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. 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