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diff --git a/docs/manual/howto/ssi.html.en b/docs/manual/howto/ssi.html.en deleted file mode 100644 index da17836b41..0000000000 --- a/docs/manual/howto/ssi.html.en +++ /dev/null @@ -1,521 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> -<html> -<head> -<title>Apache Tutorial: Introduction to Server Side Includes</title> -<link rev="made" href="mailto:rbowen@rcbowen.com"> -</head> -<!-- Background white, links blue (unvisited), navy (visited), red (active) --> -<body bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#000080" -alink="#FF0000"> -<!--#include virtual="header.html" --> -<h1 align="CENTER">Apache Tutorial: Introduction to Server Side -Includes</h1> - -<a 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 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 HOWTO first appeared in Apache Today -(http://www.apachetoday.com/) as a series of three articles. They -appear here by arrangement with ApacheToday and Internet.com.</p> - -<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 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 name="configuringyourservertopermitssi">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> - Options +Includes -</pre> - -<p>This tells Apache that you want to permit files to be parsed for SSI -directives.</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 - <FilesMatch "\.shtml[.$]"> - SetOutputFilter INCLUDES<br> - </FilesMatch> -</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 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 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 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> - -<h3><a name="includingtheresultsofacgiprogram">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> - -<pre> - <!--#include virtual="/cgi-bin/counter.pl" --> -</pre> - -<hr> -<h2><a name="additionalexamples">Additional examples</a></h2> - -<p>Following are some specific examples of things you can do in your -HTML documents with SSI.</p> - -<hr> -<h2><a name="whenwasthisdocumentmodified">When was this document -modified?</a></h2> - -<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> - -<pre> - <!--#config timefmt="%A %B %d, %Y" --> - This file last modified <!--#flastmod file="ssi.shtml" --> -</pre> - -<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> - -<pre> - <!--#config timefmt="%D" --> - This file last modified <!--#echo var="LAST_MODIFIED" --> -</pre> - -<p>For more details on the <code>timefmt</code> format, go to your -favorite search site and look for <code>ctime</code>. The syntax is the -same.</p> - -<hr> -<h2><a name="includingastandardfooter">Including a standard -footer</a></h2> - -<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> element 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> - -<pre> - <!--#include virtual="/footer.html" --> -</pre> - -<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> - -<hr> -<h2><a name="whatelsecaniconfig">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> - -<pre> - [an error occurred while processing this directive] -</pre> - -<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> -element:</p> - -<pre> - <!--#config errmsg="[It appears that you don't know how to use SSI]" --> -</pre> - -<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> - -<hr> -<h2><a name="executingcommands">Executing commands</a></h2> - -<p>I expect that I'll have an article some time in the coming months -about using SSI with small CGI programs. For now, here's something else -that you can do with the <code>exec</code> element. 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> - -<pre> - <pre> - <!--#exec cmd="ls" --> - </pre> -</pre> - -<p>or, on Windows</p> - -<pre> - <pre> - <!--#exec cmd="dir" --> - </pre> -</pre> - -<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> - -<hr> -<h2><a name="advancedssitechniques">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="caveat">Caveat</a></h3> - -<p>Most of the features discussed in this article are only available to -you if you are running Apache 1.2 or later. Of course, if you are not -running Apache 1.2 or later, you need to upgrade immediately, if not -sooner. Go on. Do it now. We'll wait.</p> - -<hr> -<h2><a name="settingvariables">Setting variables</a></h2> - -<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> - -<pre> - <!--#set var="name" value="Rich" --> -</pre> - -<p>In addition to merely setting values literally like that, you can -use any other variable, including, for example, environment variables, -or some of the variables we discussed in the last article (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> - -<pre> - <!--#set var="modified" value="$LAST_MODIFIED" --> -</pre> - -<p>To put a literal dollar sign into the value of your variable, you -need to escape the dollar sign with a backslash.</p> - -<pre> - <!--#set var="cost" value="\$100" --> -</pre> - -<p>Finally, if you want to put a variable in the midst of a longer -string, and there's a chance that the name of the variable will run up -against some other characters, and thus be confused with those -characters, you can place the name of the variable in braces, to remove -this confusion. (It's hard to come up with a really good example of -this, but hopefully you'll get the point.)</p> - -<pre> - <!--#set var="date" value="${DATE_LOCAL}_${DATE_GMT}" --> -</pre> - -<hr> -<h2><a name="conditionalexpressions">Conditional expressions</a></h2> - -<p>Now that we have variables, and are able to set and compare their -values, we can use them to express conditionals. This lets SSI be a -tiny programming language of sorts. <code>mod_include</code> provides -an <code>if</code>, <code>elif</code>, <code>else</code>, -<code>endif</code> structure for building conditional statements. This -allows you to effectively generate multiple logical pages out of one -actual page.</p> - -<p>The structure of this conditional construct is:</p> - -<pre> - <!--#if expr="test_condition" --> - <!--#elif expr="test_condition" --> - <!--#else --> - <!--#endif --> -</pre> - -<p>A <em>test_condition</em> can be any sort of logical comparison - -either comparing values to one another, or testing the ``truth'' of a -particular value. (A given string is true if it is nonempty.) For a -full list of the comparison operators available to you, see the -<code>mod_include</code> documentation. Here are some examples of how -one might use this construct.</p> - -<p>In your configuration file, you could put the following line:</p> - -<pre> - BrowserMatchNoCase macintosh Mac - BrowserMatchNoCase MSIE InternetExplorer -</pre> - -<p>This will set environment variables ``Mac'' and ``InternetExplorer'' -to true, if the client is running Internet Explorer on a Macintosh.</p> - -<p>Then, in your SSI-enabled document, you might do the following:</p> - -<pre> - <!--#if expr="${Mac} && ${InternetExplorer}" --> - Apologetic text goes here - <!--#else --> - Cool JavaScript code goes here - <!--#endif --> -</pre> - -<p>Not that I have anything against IE on Macs - I just struggled for a -few hours last week trying to get some JavaScript working on IE on a -Mac, when it was working everywhere else. The above was the interim -workaround.</p> - -<p>Any other variable (either ones that you define, or normal -environment variables) can be used in conditional statements. With -Apache's ability to set environment variables with the -<code>SetEnvIf</code> directives, and other related directives, this -functionality can let you do some pretty involved dynamic stuff without -ever resorting to CGI.</p> - -<hr> -<h2><a name="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> -</body> -</html> - |