Automating the Change of WordPress Permalinks

WordPress is powering 35% of website. And while it may not be seen as very complex or interesting, it is one of the most prevalent technologies of our time. And many developers, even if they are not working with PHP, have to support some WordPress installation (e.g. a blog like this one). And unfortunately, there are still basic things that you can’t easily do. Plugins do help, but they don’t always have the proper functionality.

Today I had to change permalinks on a website. From to And WordPress allows that, except there’s a problem – when you change it, the old links stop working (404). Not only that ruins your SEO, any previous share of your post will not work. I’ve pointed that out a long time ago when Spring broke their documentation links. Bottomline: you don’t want that to happen.

Instead, you want to do 301 redirect (and not 302, which appears to also break your SEO). But all tutorials that are easily found online assume you can manually configure redirection through some plugin. But if you have 100-200 posts, that’s a lot of tedious work. There are plugins that allegedly monitor your posts for changes and create the redirects automatically. That may work if you manually edit a post, but it didn’t work for me when changing the permalink format settings.

So how to do it in an automated way and without disrupting your website? You’d need a little bit more than a plugin – namely SQL and Regex. Here are the steps:

  1. Install and activate the Redirection plugin
  2. Open your blog’s hosting admin page and navigate to the PhpMyAdmin to browse your MySQL database. That’s the typical setup. If you are using another database admin tool, you’ll know what to do
  3. Run a query to fetch the post name of all published posts: SELECT post_name FROM `wpgk_posts` where post_type = "post" and post_status = "publish" LIMIT 200 (if you have more than 200 posts, increase the limit; if you don’t put a limit, PhpMyAdmin puts a default one)
  4. Expand the retrieved text (with the big T), select all records with the checkbox below and click “Copy to keyboard”
  5. Paste in Notepad++ (or any regex-supporting text editor, or if you are running Linux, just create a file and then you’ll be able to do regex replaces wit sed)
  6. Replace all tabs that you may have copied (\t)
  7. Then replace (.+) with /$1/,/blog/$1/ (if you are redirecting /postname to /blog/postname, otherwise you have to write the appropriate regex)
  8. Change the permalink format settings
  9. Import the resulting CSV file in the Redirection plugin. It interprets it as: source,target. That way you have redirected all your existing posts to their new permalink (the redirects are created in the chosen group). Note the trailing slash. Just in case, you may repeat the same operation to produce another CSV without the trailing slashes, but the canonical WordPress URL is with the trailing slash.

It feels a bit awkward that such an obvious things that probably happens often would need such a non-trivial set of steps to do automatically. But software, no matter how user-friendly and “no code”, will require knowledge of basic things like SQL and Regex. And maybe that’s good.

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