Backported Doc change for sections.html, moved example sections to highligh.

to another site only if the server is started using

<code>httpd -DClosedForNow</code>:</p>

<example>

&lt;IfDefine ClosedForNow&gt;<br />

Redirect / http://otherserver.example.com/<br />

<highlight language="config">

<IfDefine ClosedForNow>

    Redirect / http://otherserver.example.com/

</IfDefine>

</example>

</highlight>

<p>The <directive type="section" module="core">IfModule</directive>

directive is very similar, except it encloses directives that will

module="mod_mime_magic">MimeMagicFile</directive> directive will be

applied only if <module>mod_mime_magic</module> is available.</p>

<example>

&lt;IfModule mod_mime_magic.c&gt;<br />

MimeMagicFile conf/magic<br />

<highlight language="config">

<IfModule mod_mime_magic.c>

    MimeMagicFile conf/magic

</IfModule>

</example>

</highlight>

<p>The <directive type="section" module="mod_version">IfVersion</directive>

directive is very similar to <directive type="section"

module is designed for the use in test suites and large networks which have to

deal with different httpd versions and different configurations.</p>

<example>

  &lt;IfVersion >= 2.1&gt;<br />

  <indent>

    # this happens only in versions greater or<br />

    # equal 2.1.0.<br />

  </indent>

<highlight language="config">

<IfVersion >= 2.1>

    # this happens only in versions greater or

    # equal 2.1.0.

</IfVersion>

</example>

</highlight>

<p><directive type="section" module="core">IfDefine</directive>,

<directive type="section" module="core">IfModule</directive>, and the

following configuration, directory indexes will be enabled for the

<code>/var/web/dir1</code> directory and all subdirectories.</p>

<example>

&lt;Directory /var/web/dir1&gt;<br />

Options +Indexes<br />

<highlight language="config">

<Directory /var/web/dir1>

    Options +Indexes

</Directory>

</example>

</highlight>

<p>Directives enclosed in a <directive type="section"

module="core">Files</directive> section apply to any file with

deny access to any file named <code>private.html</code> regardless

of where it is found.</p>

<example>

&lt;Files private.html&gt;<br />

Order allow,deny<br />

Deny from all<br />

<highlight language="config">

<Files private.html>

    Order allow,deny

    Deny from all

</Files>

</example>

</highlight>

<p>To address files found in a particular part of the filesystem, the

<directive type="section" module="core">Files</directive> and

of <code>private.html</code> found under the <code>/var/web/dir1/</code>

directory.</p>

<example>

&lt;Directory /var/web/dir1&gt;<br />

&lt;Files private.html&gt;<br />

Order allow,deny<br />

Deny from all<br />

&lt;/Files&gt;<br />

<highlight language="config">

<Directory /var/web/dir1>

    <Files private.html>

        Order allow,deny

        Deny from all

    </Files>

</Directory>

</example>

</highlight>

</section>

<section id="webspace"><title>Webspace Containers</title>

<code>http://yoursite.example.com/private/dir/file.html</code> as well

as any other requests starting with the <code>/private</code> string.</p>

<example>

&lt;LocationMatch ^/private&gt;<br />

Order Allow,Deny<br />

Deny from all<br />

<highlight language="config">

<LocationMatch ^/private>

    Order Allow,Deny

    Deny from all

</LocationMatch>

</example>

</highlight>

<p>The <directive type="section" module="core">Location</directive>

directive need not have anything to do with the filesystem.

No file called <code>server-status</code> needs to exist in the

filesystem.</p>

<example>

&lt;Location /server-status&gt;<br />

SetHandler server-status<br />

<highlight language="config">

<Location /server-status>

    SetHandler server-status

</Location>

</example>

</highlight>

</section>

<section id="wildcards"><title>Wildcards and Regular Expressions</title>

<p>A non-regex wildcard section that changes the configuration of

all user directories could look as follows:</p>

<example>

&lt;Directory /home/*/public_html&gt;<br />

Options Indexes<br />

<highlight language="config">

<Directory /home/*/public_html>

    Options Indexes

</Directory>

</example>

</highlight>

<p>Using regex sections, we can deny access to many types of image files

at once:</p>

<example>

&lt;FilesMatch \.(?i:gif|jpe?g|png)$&gt;<br />

Order allow,deny<br />

Deny from all<br />

<highlight language="config">

<FilesMatch \.(?i:gif|jpe?g|png)$>

    Order allow,deny

    Deny from all

</FilesMatch>

</example>

</highlight>

</section>

location, allowing your restrictions to be circumvented.

For example, consider the following configuration:</p>

<example>

&lt;Location /dir/&gt;<br />

Order allow,deny<br />

Deny from all<br />

<highlight language="config">

<Location /dir/>

    Order allow,deny

    Deny from all

</Location>

</example>

</highlight>

<p>This works fine if the request is for

<code>http://yoursite.example.com/dir/</code>.  But what if you are on

containers apply enclosed configuration directives only

to sites accessed through <module>mod_proxy</module>'s proxy server

that match the specified URL. For example, the following configuration

will prevent the proxy server from being used to access the

<code>cnn.com</code> website.</p>

<example>

&lt;Proxy http://cnn.com/*&gt;<br />

Order allow,deny<br />

Deny from all<br />

will allow only a subset of clients to access the

<code>www.example.com</code> website using the proxy server:</p>

<highlight language="config">

<Proxy "http://www.example.com/*">

    Order allow,deny

    Allow from 192.168.1.104 192.168.1.205

    Deny from all

</Proxy>

</example>

</highlight>

</section>

<section id="whatwhere"><title>What Directives are Allowed?</title>

    type="section">Directory</directive> container in the processing

    order.</p>

    <p>Later sections override earlier ones.</p>

    <note><title>Technical Note</title>

      There is actually a

      <code>&lt;Location&gt;</code>/<code>&lt;LocationMatch&gt;</code>

      completed.

    </note>

<section id="relationship-module-configuration"><title>Relationship between modules and configuration sections</title>

    <p>One question that often arises after reading how configuration sections are

    merged is related to how and when directives of specific modules like <module>mod_rewrite</module>

    are processed. The answer is not trivial and needs a bit of background. 

    Each httpd module manages its own configuration, and each of its directives in httpd.conf specify one piece 

    of configuration in a particular context. httpd does not execute a command as it is read.</p>

    <p>At runtime, the core of httpd iterates over the defined configuration sections in the order

    described above to determine which ones apply to the current request. When the first section matches, 

    it is considered the current configuration for this request. If a subsequent section matches too, 

    then each module with a directive in either of the sections is given a chance to merge its configuration between the two sections. The result is a third configuration, and the process goes on until all the configuration sections

    are evaluated.</p>

    <p>After the above step, the "real" processing of the HTTP request begins: each module has a chance to run 

    and perform whatever tasks they like. They can retrieve their own final merged configuration from the core

    of the httpd to determine how they should act.</p>

    <p>An example can help to visualize the whole process. The following configuration uses the 

        <directive module="mod_headers">Header</directive> directive of <module>mod_headers</module> to set

        a specific HTTP header. What value will httpd set in the <code>CustomHeaderName</code> header for a request to

        <code>/example/index.html</code> ?

    </p>

    <highlight language="config">

<Directory "/">

    Header set CustomHeaderName one

    <FilesMatch ".*">

        Header set CustomHeaderName three

    </FilesMatch>

</Directory>

<Directory "/example">

    Header set CustomHeaderName two

</Directory>

    </highlight>    

    <ul>

        <li><directive>Directory</directive> "/" matches and an initial configuration to set the <code>CustomHeaderName</code> header with the value <code>one</code> is created.</li>

        <li><directive>Directory</directive> "/example" matches, and since <module>mod_headers</module> specifies in its code to override in case of a merge, a new configuration is created to set the <code>CustomHeaderName</code> header with the value <code>two</code>.</li>

        <li><directive>FilesMatch</directive> ".*" matches and another merge opportunity arises, causing the <code>CustomHeaderName</code> header to be set with the value <code>three</code>.</li>

        <li>Eventually during the next steps of the HTTP request processing <module>mod_headers</module> will be called and it will receive the configuration to set the <code>CustomHeaderName</code> header with the value <code>three</code>. <module>mod_headers</module> normally uses this configuration to perfom its job, namely setting the foo header. This does not mean that a module can't perform a more complex action like discarding directives because not needed or deprecated, etc..</li>

    </ul>

    <p>This is true for .htaccess too since they have the same priority as <directive>Directory</directive> in the merge order. The important concept to understand is that configuration sections like  <directive>Directory</directive> and <directive>FilesMatch</directive> are not comparable to module specific directives like <directive module="mod_headers">Header</directive> or <directive module="mod_rewrite">RewriteRule</directive> because they operate on different levels.

    </p>

</section>

<section id="merge-examples"><title>Some Examples</title>

<p>Below is an artificial example to show the order of

this example will be applied in the order A > B > C > D >

E.</p>

<example>

&lt;Location /&gt;<br />

E<br />

&lt;/Location&gt;<br />

<br />

&lt;Files f.html&gt;<br />

D<br />

&lt;/Files&gt;<br />

<br />

&lt;VirtualHost *&gt;<br />

&lt;Directory /a/b&gt;<br />

B<br />

&lt;/Directory&gt;<br />

&lt;/VirtualHost&gt;<br />

<br />

&lt;DirectoryMatch "^.*b/"&gt;<br />

C<br />

&lt;/DirectoryMatch&gt;<br />

<br />

&lt;Directory /a/b&gt;<br />

A<br />

&lt;/Directory&gt;<br />

<br />

</example>

<highlight language="config">

<Location "/">

    E

</Location>

<Files "f.html">

    D

</Files>

<VirtualHost *>

<Directory "/a/b">

    B

</Directory>

</VirtualHost>

<DirectoryMatch "^.*b$">

    C

</DirectoryMatch>

<Directory "/a/b">

    A

</Directory>

</highlight>

<p>For a more concrete example, consider the following.  Regardless of

any access restrictions placed in <directive module="core"

evaluated last and will allow unrestricted access to the server.  In

other words, order of merging is important, so be careful!</p>

<example>

&lt;Location /&gt;<br />

Order deny,allow<br />

Allow from all<br />

&lt;/Location&gt;<br />

<br />

# Woops!  This &lt;Directory&gt; section will have no effect<br />

&lt;Directory /&gt;<br />

Order allow,deny<br />

Allow from all<br />

Deny from badguy.example.com<br />

<highlight language="config">

<Location "/">

    Require all granted

</Location>

# Woops!  This <Directory> section will have no effect

<Directory "/">

    <RequireAll>

        Require all granted

        Require not host badguy.example.com

    </RequireAll>

</Directory>

</example>

</highlight>

</section>