Apache Module mod_dir

Description:	Provides for "trailing slash" redirects and serving directory index files
Status:	Base
Module Identifier:	dir_module
Source File:	mod_dir.c

Summary

The index of a directory can come from one of two sources:

A file written by the user, typically called index.html. The DirectoryIndex directive sets the name of this file. This is controlled by mod_dir.
Otherwise, a listing generated by the server. This is provided by mod_autoindex.

The two functions are separated so that you can completely remove (or replace) automatic index generation should you want to.

A "trailing slash" redirect is issued when the server receives a request for a URL http://servername/foo/dirname where dirname is a directory. Directories require a trailing slash, so mod_dir issues a redirect to http://servername/foo/dirname/.

DirectoryIndex Directive

Description:	List of resources to look for when the client requests a directory
Syntax:	`DirectoryIndex local-url [local-url] ...`
Default:	`DirectoryIndex index.html`
Context:	server config, virtual host, directory, .htaccess
Override:	Indexes
Status:	Base
Module:	mod_dir

The DirectoryIndex directive sets the list of resources to look for, when the client requests an index of the directory by specifying a / at the end of the directory name. Local-url is the (%-encoded) URL of a document on the server relative to the requested directory; it is usually the name of a file in the directory. Several URLs may be given, in which case the server will return the first one that it finds. If none of the resources exist and the Indexes option is set, the server will generate its own listing of the directory.

Example

DirectoryIndex index.html

then a request for http://myserver/docs/ would return http://myserver/docs/index.html if it exists, or would list the directory if it did not.

Note that the documents do not need to be relative to the directory;

DirectoryIndex index.html index.txt /cgi-bin/index.pl

would cause the CGI script /cgi-bin/index.pl to be executed if neither index.html or index.txt existed in a directory.

DirectorySlash Directive

Description:	Toggle trailing slash redirects on or off
Syntax:	`DirectorySlash On\|Off`
Default:	`DirectorySlash On`
Context:	server config, virtual host, directory, .htaccess
Override:	Indexes
Status:	Base
Module:	mod_dir
Compatibility:	Available in version 2.0.51 and later

The DirectorySlash directive determines, whether mod_dir should fixup URLs pointing to a directory or not.

Typically if a user requests a resource without a trailing slash, which points to a directory, mod_dir redirects him to the same resource, but with trailing slash for some good reasons:

The user is finally requesting the canonical URL of the resource
mod_autoindex works correctly. Since it doesn't emit the path in the link, it would point to the wrong path.
DirectoryIndex will be evaluated only for directories requested with trailing slash.
Relative URL references inside html pages will work correctly.

Well, if you don't want this effect and the reasons above don't apply to you, you can turn off the redirect with:

# see security warning below! <Location /some/path> DirectorySlash Off SetHandler some-handler </Location>

Security Warning

Turning off the trailing slash redirect may result in an information disclosure. Consider a situation where mod_autoindex is active (Options +Indexes) and DirectoryIndex is set to a valid resource (say, index.html) and there's no other special handler defined for that URL. In this case a request with a trailing slash would show the index.html file. But a request without trailing slash would list the directory contents.