<div class="section">
<h2><a name="setenv" id="setenv">Environment Variable Testing</a></h2>
-<div class="note">Parts of this section are applicable only to Apache HTTP
-Server 2.3 and later.</div>
-
<p>Using SetEnvIf and <If> (2.3 and later.)</p>
+<p><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> is frequently used to take a particular
+action based on the presence or absense of a particular environment
+variable or request header. This can be done more efficiently using the
+<code class="directive"><a href="../mod/core.html#if"><If></a></code>.</p>
+
+<p>Consider, for example, the common scenario where
+<code class="directive">RewriteRule</code> is used to enforce a canonical
+hostname, such as <code>www.example.com</code> instead of
+<code>example.com</code>. This can be done using the <code class="directive"><a href="../mod/core.html#if"><If></a></code> direct, as shown here:</p>
+
+<div class="example"><p><code>
+<If "$req{Host} = 'example.com'"><br />
+RedirectMatch (.*) http://www.example.com$1
+</If>
+</code></p></div>
+
+<p>This technique can be used to take actions based on any request
+header, response header, or environment variable, replacing
+<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> in many common scenarios.</p>
+
</div></div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="../en/rewrite/avoid.html" title="English"> en </a></p>
<section id="setenv"><title>Environment Variable Testing</title>
-<note type="note">Parts of this section are applicable only to Apache HTTP
-Server 2.3 and later.</note>
-
<p>Using SetEnvIf and <If> (2.3 and later.)</p>
+<p><module>mod_rewrite</module> is frequently used to take a particular
+action based on the presence or absense of a particular environment
+variable or request header. This can be done more efficiently using the
+<directive module="core" type="section">If</directive>.</p>
+
+<p>Consider, for example, the common scenario where
+<directive>RewriteRule</directive> is used to enforce a canonical
+hostname, such as <code>www.example.com</code> instead of
+<code>example.com</code>. This can be done using the <directive
+module="core" type="section">If</directive> direct, as shown here:</p>
+
+<example>
+<If "$req{Host} = 'example.com'"><br />
+RedirectMatch (.*) http://www.example.com$1
+</If>
+</example>
+
+<p>This technique can be used to take actions based on any request
+header, response header, or environment variable, replacing
+<module>mod_rewrite</module> in many common scenarios.</p>
+
</section>
</manualpage>