The Directory and Files directives, along with their regex counterparts, apply directives to parts of the filesystem. Directives enclosed in a Directory section apply to the named filesystem directory and all subdirectories of that directory (as well as the files in those directories). The same effect can be obtained using .htaccess files. For example, in the following configuration, directory indexes will be enabled for the /var/web/dir1 directory and all subdirectories.

Directives enclosed in a Files section apply to any file with the specified name, regardless of what directory it lies in. So for example, the following configuration directives will, when placed in the main section of the configuration file, deny access to any file named private.html regardless of where it is found.

To address files found in a particular part of the filesystem, the Files and Directory sections can be combined. For example, the following configuration will deny access to /var/web/dir1/private.html, /var/web/dir1/subdir2/private.html, /var/web/dir1/subdir3/private.html, and any other instance of private.html found under the /var/web/dir1/ directory.

The Location directive and its regex counterpart, on the other hand, change the configuration for content in the webspace. For example, the following configuration prevents access to any URL-path that begins in /private. In particular, it will apply to requests for http://yoursite.example.com/private, http://yoursite.example.com/private123, and http://yoursite.example.com/private/dir/file.html as well as any other requests starting with the /private string.

The Location directive need not have anything to do with the filesystem. For example, the following example shows how to map a particular URL to an internal Apache HTTP Server handler provided by mod_status. No file called server-status needs to exist in the filesystem.

In order to have two overlapping URLs one has to consider the order in which certain sections or directives are evaluated. For Location this would be:

Aliases on the other hand, are mapped vice-versa:

The same is true for the ProxyPass directives:

The Directory, Files, and Location directives can each use shell-style wildcard characters as in fnmatch from the C standard library. The character "*" matches any sequence of characters, "?" matches any single character, and "[seq]" matches any character in seq. The "/" character will not be matched by any wildcard; it must be specified explicitly.

If even more flexible matching is required, each container has a regular expression (regex) counterpart DirectoryMatch, FilesMatch, and LocationMatch that allow perl-compatible regular expressions to be used in choosing the matches. But see the section below on configuration merging to find out how using regex sections will change how directives are applied.

A non-regex wildcard section that changes the configuration of all user directories could look as follows:

Using regex sections, we can deny access to many types of image files at once:

Regular expressions containing named groups and backreferences are added to the environment with the corresponding name in uppercase. This allows elements of filename paths and URLs to be referenced from within expressions and modules like mod_rewrite.

The If directive change the configuration depending on a condition which can be expressed by a boolean expression. For example, the following configuration denies access if the HTTP Referer header does not start with "http://www.example.com/".

Choosing between filesystem containers and webspace containers is actually quite easy. When applying directives to objects that reside in the filesystem always use Directory or Files. When applying directives to objects that do not reside in the filesystem (such as a webpage generated from a database), use Location.

It is important to never use Location when trying to restrict access to objects in the filesystem. This is because many different webspace locations (URLs) could map to the same filesystem location, allowing your restrictions to be circumvented. For example, consider the following configuration:

This works fine if the request is for http://yoursite.example.com/dir/. But what if you are on a case-insensitive filesystem? Then your restriction could be easily circumvented by requesting http://yoursite.example.com/DIR/. The Directory directive, in contrast, will apply to any content served from that location, regardless of how it is called. (An exception is filesystem links. The same directory can be placed in more than one part of the filesystem using symbolic links. The Directory directive will follow the symbolic link without resetting the pathname. Therefore, for the highest level of security, symbolic links should be disabled with the appropriate Options directive.)

If you are, perhaps, thinking that none of this applies to you because you use a case-sensitive filesystem, remember that there are many other ways to map multiple webspace locations to the same filesystem location. Therefore you should always use the filesystem containers when you can. There is, however, one exception to this rule. Putting configuration restrictions in a <Location "/"> section is perfectly safe because this section will apply to all requests regardless of the specific URL.

Some section types can be nested inside other section types. On the one hand, Files can be used inside Directory. On the other hand, If can be used inside Directory, Location, and Files sections (but not inside another If). The regex counterparts of the named section behave identically.

Nested sections are merged after non-nested sections of the same type.

One question that often arises after reading how configuration sections are merged is related to how and when directives of specific modules like mod_rewrite 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.

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.

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.

An example can help to visualize the whole process. The following configuration uses the Header directive of mod_headers to set a specific HTTP header. What value will httpd set in the CustomHeaderName header for a request to /example/index.html ?

• Directory "/" matches and an initial configuration to set the CustomHeaderName header with the value one is created.
• Directory "/example" matches, and since mod_headers specifies in its code to override in case of a merge, a new configuration is created to set the CustomHeaderName header with the value two.
• FilesMatch ".*" matches and another merge opportunity arises, causing the CustomHeaderName header to be set with the value three.
• Eventually during the next steps of the HTTP request processing mod_headers will be called and it will receive the configuration to set the CustomHeaderName header with the value three. mod_headers normally uses this configuration to perform 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..

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

Below is an artificial example to show the order of merging. Assuming they all apply to the request, the directives in this example will be applied in the order A > B > C > D > E.

For a more concrete example, consider the following. Regardless of any access restrictions placed in Directory sections, the Location section will be evaluated last and will allow unrestricted access to the server. In other words, order of merging is important, so be careful!