301 Permanent Redirect by Brian V. Bonini
New domain name?
Need to change a file name?
Hierarchy of your servers directory structure change?
meta http-equiv="refresh"... is highly frowned on by search engines and is commonly used by spammers. As such, THIS SHOULD BE AVOIDED.
A 301 Redirect as it is commonly referred to will allow you to make these changes without compromising your hard earned SEO results.
Using the Apache web server, fortunately this is a simply task.
There are a few different places you can set various 'Redirect' directives such as your servers main configuration file (typically httpd.conf) or within a 'Virtual Host' container inside one of your server configuration files. The final method and the one we will be discussing here is using your servers directory Auth file (AKA: .htaccess).
The first thing you do is create a file named .htaccess
There are a couple different way to approach this but in it most simple form you can just issue a 'Redirect' request in your .htaccess file like so:
Redirect /foo http://foobar.com/foo
In this example if the client requests
http://myserver.com/foo/foobar.txt,
it will be told to access
http://foobar.com/foo/foobar.txt instead.
Now this is not quite complete yet, since we need to specifically send a 301 status code. Without the status argument "Redirect" will send a temporary redirect status (302). So we simply take the above example and change it to:
Redirect 301 /foo http://foobar.com/foo
OR
Redirect permanent /foo http://foobar.com/foo
And there is also a specific 'RedirectPermanent' directive as well so you could just as easily say:
RedirectPermanent /foo http://foobar.com/foo
So far so good? Excellent. So now you ask what if I want to change ALL my .htm files to .html. Introducing 'RedirectMatch' which makes use of standard regular expression syntax.
RedirectMatch (.*)\.htm$ http://myserver.com$1.html
Going into an in depth explanation of regular expression if beyond the scope of this tutorial but a quick Google search for "Perl compatible regular expression syntax" should set you on your way.
What the above example does is match any character '.' any number of times '*', i.e., that is it will match everything. (.*) the parenthesis group the result into a variable which we will use with a back-reference ($1) later in the directive. Next, '\' simply escapes the following '.'. Since '.' has special meaning in regular expression syntax we need to escape it if we want to use it in the literal sense, '\' provides the escape sequence. Next is the '.htm' which we know is a static part of the search string we're looking for followed by '$' which simply marks the end of the pattern in a regular expression (regex). So the above example takes any file with an .htm extension and redirects the client to the same file at the location specified, i.e., http://myserver.com$1.html
But wait, what's that '$1'? Well remember we said we were going to store a variable for use in a back reference later, well here it is. The '$1' simply says that whatever was in (.*) is now represented by $1
So, the client request for example foobar.htm, the above directive matches this and redirects the client to http://myserver.com/foobar.html because 'foobar' is stored in '$1'. Just as with 'Redirect', 'RedirectMatch' takes a status argument so to issue a 301 (permanent) redirect we do this:
RedirectMatch 301 (.*)\.htm$ http://myserver.com$1.html
Another method we can use is via mod_rewrite. This requires that the mod_rewrite module is active on your webserver. It usually is and is done by the system administrators when they installed the webserver. mod_rewrite is a very powerful URL re-writing engine and we will only by scratching a hair on its head here.
Again, in your .htaccess file
RewriteEngine ON
RewriteRule ^(.*)$ http://mynewdomain.com/$1 [R=301,L]
The above example will re-map your old domain to a new one and issue a 301 status code (permanent redirect). So a request for
http://olddomain.com/foobar.html will go to
http://mynewdomain.com/foobar.html
If you simply want to redirect all requests regardless of the page requested to the new domain you could use:
RewriteRule /.* http://mynewdomain.com/ [R=301,L]
In this case no matter what file or directory is requested they will all go to
http://mynewdomain.com/ i.e., http://myolddomain.com/foobar.html
will go to http://mynewdomain.com/
The [R=301,L] means redirect the client and send a 301 status code (R=301) and make this the last rule (L).
Whichever method you decide on, once completed upload the resulting file to your webservers document root and you should be on your way.
Related 301 Redirect and Resources
- Mod Rewrite
http://httpd.apache.org/docs-2.0/mod/mod_rewrite.html - URL Rewriting Guide
http://httpd.apache.org/docs-2.0/misc/rewriteguide.html - Redirect Directives
http://httpd.apache.org/docs-2.0/mod/directives.html#R
Also, a Google search for '301 redirect+seo' or 'mod_rewrite+301 redirect' should turn up tons of information.