How to Update Your WordPress Permalinks Without Causing Link Rot

If you are chang­ing your perma­links struc­ture dif­fer­ently than what is described below (e.g., going from name-based perma­links back to name and date-based perma­links), there is a Word­Press plu­gin that can take care of you. If all you want to do is change from name and date-based perma­links to name-based perma­links, the method described below should be a bit faster, as the redi­rect is han­dled at the server level rather than at the PHP level.

This is a follow-up to my ear­lier post Seam­less Perma­link Updat­ing. The prob­lem I faced was that I wanted to change my Word­Press perma­link set­tings from being date and name based to some­thing which was sim­ply name based.

Why did I want to do this?

1. Perma­links would be shorter; remov­ing the date infor­ma­tion results in URIs which are eleven char­ac­ters shorter.
2. Perma­links would not only be more read­able, they would be more mean­ing­ful to humans; dates aren’t as impor­tant as the con­tent the page itself con­tains. If pre­sented with a list of perma­links from this site, users should have a good idea of what they’ll get when they click them. There’s no rea­son to muddy those waters by inject­ing date infor­ma­tion into the mix, dilut­ing the impact of the domain and post slug.
3. The con­tent part of the perma­links (domain name + post slug) would carry more impact in var­i­ous search engines, with­out date infor­ma­tion (that may or may not be rec­og­nized as dates by search engine algo­rithms) dilut­ing the value of what­ever key­words may be present.
4. Yes, this is a blog, and yes infor­ma­tion is posted chrono­log­i­cally; how­ever, this isn’t a novel, and the mate­r­ial here need not be read in a chrono­log­i­cal man­ner in order to under­stand it. Hav­ing date-based perma­links cre­ates the illu­sion that the date the mate­r­ial was posted is more impor­tant than it really is. Besides, posts are dis­played with the date any­way; why give it to the user twice when I’m bet­ting the date included with the post is glanced over by most users.

Great rea­sons, I think, which should suf­fice for now. So I wanted to change my perma­links; what did I do about it?

Word­Press makes the process ridicu­lously simple.

1. Visit the Perma­links page of the admin­is­tra­tion panel (/wp-admin/options-permalink.php).
2. Select the but­ton labeled “Cus­tom, spec­ify below.”
3. In the box labeled “Cus­tom struc­ture,” enter the text /%postname%/
4. Sub­mit the change via the “Update Perma­link Struc­ture »” button.
5. Visit your site and ver­ify that posts are not being given perma­links in the style example.com/post-name-here/. Beau­ti­ful, no?

Like I said, ridicu­lously easy!

But con­sider: What hap­pens to all the links out there on the Inter­net to your blog which make use of the pre­vi­ous style of perma­links? Try it out for your­self; find an old perma­link in your browser’s his­tory that still makes use of “Date and name based” perma­links and visit it.

404! You broke the Inter­net! File not found! It’s the end of the world as you know it!

But don’t worry, you can feel fine about it because I have a solu­tion, pro­vided that you are using Apache as your server envi­ron­ment (chances are, you are) and mod_alias is enabled (I’m unsure how com­mon it is). We’ll be fix­ing our prob­lem using the RedirectMatch direc­tive of mod_alias.

1. Down­load your blog’s pri­mary .htaccess file; most likely, it’ll be in the same direc­tory as your blog’s wp-config.php file.

2. Open it up, and find Word­Press’ perma­links code. If you’ve never edited your .htaccess file before, it will most likely be the only code present. The code looks like this, give or take a line break:

   # BEGIN WordPress
   <IfModule mod_rewrite.c>
   RewriteEngine On
   RewriteBase /
   RewriteCond %{REQUEST_FILENAME} !-f
   RewriteCond %{REQUEST_FILENAME} !-d
   RewriteRule . /index.php [L]
   </IfModule>
   # END WordPress

3. Before that Word­Press code, you’ll want to add one of the following:

   • If your Word­Press is installed in your domain’s root direc­tory (e.g., example.com/wp-config.php), add this code, adjust­ing example.com to your proper domain name:

     RedirectMatch permanent ^/[0-9]{4}/[0-9]{2}/[0-9]{2}/([a-z0-9\-/]+) http://example.com/$1

   • If your Word­Press is installed in a sub­di­rec­tory of your domain (e.g., example.com/blog/wp-config.php), add this code, adjust­ing example.com/blog to your proper domain name and directory:

     RedirectMatch permanent /blog/[0-9]{4}/[0-9]{2}/[0-9]{2}/([a-z0-9\-/]+) http://example.com/blog/$1

4. Save & upload the .htaccess file, and revisit one of your older date-based perma­links. If all went accord­ing to plan, you should be seam­lessly redi­rected to your new name-based permalinks.

That’s all there is to it! If any­one can pro­vide a bet­ter means, I’m open to it, but I’ve tested this out, and it works exactly as I want it to — posts work, paged posts work, pages work, and so on. I can’t promise this won’t break any Word­Press plu­g­ins, so be pre­pared to give up this method (which is as easy as delet­ing what­ever you add to .htaccess and switch­ing your perma­link struc­ture back).

For the curi­ous, this is what the code above does, piece by piece:

Redi­rect­Match

Begins the call to Apache’s mod_alias module.

per­ma­nent

Sends the client (i.e., the user, whether human or robot) instruc­tion that this redi­rect is a per­ma­nent redi­rect and that the old address is invalid and should be from now on replaced with the new.

^/[0–9]{4}

The address which we’re try­ing to match begins with a four-digit year stamp, so we first look for a slash fol­lowed by four numbers.

/[0–9]{2}

The address will next have a two-digit month stamp, so we check for another slash fol­lowed by two numbers.

/[0–9]{2}

The address will next have a two-digit day stamp, so we check for yet another slash fol­lowed again by two numbers.

/([a-z0-9\-/]*)

The address will then have the post slug, which can con­sist of a vari­ety of low­er­case let­ters, num­bers, and dashes. So we look for any num­ber of those. A post slug may include addi­tional infor­ma­tion after it, such as a page num­ber on paged posts, so we include any num­ber of slashes in our search as well. It’s enclosed in paren­the­ses so we can cap­ture that data and use it in the next section.

http://example.com/$1

This is the loca­tion of where we want to redi­rect to. The $1 at the end will be replaced by what­ever was matched by the code in paren­the­ses in the pre­vi­ous statement.

Edit: Whoops! Using the above RedirectMatch code pre­vented view­ing of day archives (e.g., /2008/01/01/); swap­ping the aster­isk (*) out for a plus sign (+) resolved the issue and allows day archives to be viewed. The code above has been corrected.