Apache Module mod_dir

DirectoryCheckHandler Directive

The DirectoryCheckHandler directive determines whether mod_dir should check for directory indexes or add trailing slashes when some other handler has been configured for the current URL. Handlers can be set by directives such as SetHandler or by other modules, such as mod_rewrite during per-directory substitutions.

In releases prior to 2.4, this module did not take any action if any other handler was configured for a URL. This allows directory indexes to be served even when a SetHandler directive is specified for an entire directory, but it can also result in some conflicts with modules such as mod_rewrite.

DirectoryIndex Directive

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.

DirectoryIndex index.html

then a request for https://example.com/docs/ would return https://example.com/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.

A single argument of "disabled" prevents mod_dir from searching for an index. An argument of "disabled" will be interpreted literally if it has any arguments before or after it, even if they are "disabled" as well.

Note: Multiple DirectoryIndex directives within the same context will add to the list of resources to look for rather than replace:

# Example A: Set index.html as an index page, then add index.php to that list as well.
<Directory "/foo">
    DirectoryIndex index.html
    DirectoryIndex index.php
</Directory>

# Example B: This is identical to example A, except it's done with a single directive.
<Directory "/foo">
    DirectoryIndex index.html index.php
</Directory>

# Example C: To replace the list, you must explicitly reset it first:
# In this example, only index.php will remain as an index resource.
<Directory "/foo">
    DirectoryIndex index.html
    DirectoryIndex disabled
    DirectoryIndex index.php
</Directory>

DirectoryIndexRedirect Directive

By default, the DirectoryIndex is selected and returned transparently to the client. DirectoryIndexRedirect causes an external redirect to instead be issued.

The argument can be:

• on: issues a 302 redirection to the index resource.
• off: does not issue a redirection. This is the legacy behaviour of mod_dir.
• permanent: issues a 301 (permanent) redirection to the index resource.
• temp: this has the same effect as on
• seeother: issues a 303 redirection (also known as "See Other") to the index resource.
• 3xx-code: issues a redirection marked by the chosen 3xx code.

DirectoryIndexRedirect on

A request for https://example.com/docs/ would return a temporary redirect to https://example.com/docs/index.html if it exists.

DirectorySlash Directive

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.

If you don't want this effect and the reasons above don't apply to you, you can turn off the redirect as shown below. However, be aware that there are possible security implications to doing this.

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

Also note that some browsers may erroneously change POST requests into GET (thus discarding POST data) when a redirect is issued.

FallbackResource Directive

Use this to set a handler for any URL that doesn't map to anything in your filesystem, and would otherwise return HTTP 404 (Not Found). For example

FallbackResource /not-404.php

will cause requests for non-existent files to be handled by not-404.php, while requests for files that exist are unaffected.

It is frequently desirable to have a single file or resource handle all requests to a particular directory, except those requests that correspond to an existing file or script. This is often referred to as a 'front controller.'

In earlier versions of httpd, this effect typically required mod_rewrite, and the use of the -f and -d tests for file and directory existence. This now requires only one line of configuration.

FallbackResource /index.php

Existing files, such as images, css files, and so on, will be served normally.

Use the disabled argument to disable that feature if inheritance from a parent directory is not desired.

In a sub-URI, such as https://example.com/blog/ this sub-URI has to be supplied as local-url:

<Directory "/web/example.com/htdocs/blog">
    FallbackResource /blog/index.php
</Directory>
<Directory "/web/example.com/htdocs/blog/images">
    FallbackResource disabled
</Directory>