Apache Module mod_alias

Alias Directive

The Alias directive allows documents to be stored in the local filesystem other than under the DocumentRoot. URLs with a (%-decoded) path beginning with url-path will be mapped to local files beginning with directory-path. The url-path is case-sensitive, even on case-insenitive file systems.

A request for http://myserver/image/foo.gif would cause the server to return the file /ftp/pub/image/foo.gif. Only complete path segments are matched, so the above alias would not match a request for http://myserver/imagefoo.gif. For more complex matching using regular expressions, see the AliasMatch directive.

Note that if you include a trailing / on the url-path then the server will require a trailing / in order to expand the alias. That is, if you use Alias /icons/ /usr/local/apache/icons/ then the url /icons will not be aliased.

Note that you may need to specify additional <Directory> sections which cover the destination of aliases. Aliasing occurs before <Directory> sections are checked, so only the destination of aliases are affected. (Note however <Location> sections are run through once before aliases are performed, so they will apply.)

In particular, if you are creating an Alias to a directory outside of your DocumentRoot, you may need to explicitly permit access to the target directory.

AliasMatch Directive

This directive is equivalent to Alias, but makes use of regular expressions, instead of simple prefix matching. The supplied regular expression is matched against the URL-path, and if it matches, the server will substitute any parenthesized matches into the given string and use it as a filename. For example, to activate the /icons directory, one might use:

It is also possible to construct an alias with case-insensitive matching of the url-path:

Redirect Directive

The Redirect directive maps an old URL into a new one by asking the client to refetch the resource at the new location.

The old URL-path is a case-sensitive (%-decoded) path beginning with a slash. A relative path is not allowed. The new URL should be an absolute URL beginning with a scheme and hostname, but a URL-path beginning with a slash may also be used, in which case the scheme and hostname of the current server will be added.

Then any request beginning with URL-Path will return a redirect request to the client at the location of the target URL. Additional path information beyond the matched URL-Path will be appended to the target URL.

If the client requests http://example.com/service/foo.txt, it will be told to access http://foo2.example.com/service/foo.txt instead. Only complete path segments are matched, so the above example would not match a request for http://example.com/servicefoo.txt. For more complex matching using regular expressions, see the RedirectMatch directive.

If no status argument is given, the redirect will be "temporary" (HTTP status 302). This indicates to the client that the resource has moved temporarily. The status argument can be used to return other HTTP status codes:

permanent

Returns a permanent redirect status (301) indicating that the resource has moved permanently.

temp

Returns a temporary redirect status (302). This is the default.

seeother

Returns a "See Other" status (303) indicating that the resource has been replaced.

gone

Returns a "Gone" status (410) indicating that the resource has been permanently removed. When this status is used the URL argument should be omitted.

Other status codes can be returned by giving the numeric status code as the value of status. If the status is between 300 and 399, the URL argument must be present, otherwise it must be omitted. Note that the status must be known to the Apache code (see the function send_error_response in http_protocol.c).

RedirectMatch Directive

This directive is equivalent to Redirect, but makes use of regular expressions, instead of simple prefix matching. The supplied regular expression is matched against the URL-path, and if it matches, the server will substitute any parenthesized matches into the given string and use it as a filename. For example, to redirect all GIF files to like-named JPEG files on another server, one might use:

RedirectPermanent Directive

This directive makes the client know that the Redirect is permanent (status 301). Exactly equivalent to Redirect permanent.

RedirectTemp Directive

This directive makes the client know that the Redirect is only temporary (status 302). Exactly equivalent to Redirect temp.

ScriptAlias Directive

The ScriptAlias directive has the same behavior as the Alias directive, except that in addition it marks the target directory as containing CGI scripts that will be processed by mod_cgi's cgi-script handler. URLs with a case-sensitive (%-decoded) path beginning with URL-path will be mapped to scripts beginning with the second argument, which is a full pathname in the local filesystem.

A request for http://myserver/cgi-bin/foo would cause the server to run the script /web/cgi-bin/foo. This configuration is essentially equivalent to:

See also

• CGI Tutorial

ScriptAliasMatch Directive

This directive is equivalent to ScriptAlias, but makes use of regular expressions, instead of simple prefix matching. The supplied regular expression is matched against the URL-path, and if it matches, the server will substitute any parenthesized matches into the given string and use it as a filename. For example, to activate the standard /cgi-bin, one might use: