How to fix 301 permalink redirect for funky structure - permalinks

Question

I'm trying to figure out how to redirect the permalink structure for some of my very old WordPress news portals, which are using funky structures that were needed for Google News and old search engines, but now are crap.
For example, I currently have:
mynewssite.xcom/2015/03/19/fnw14770_161419.php
Where I'd rather have:
mynewssite.xcom/pretty-nameo-of-the-article-fnw14770/
I would even be okay with this instead:
mynewssite.xcom/pretty-name-of-the-article-fnw14770_161419.php
My current WordPress permalink structure is:
/%year%/%monthnum%/%day%/fnw%post_id%_%hour%%minute%%second%.php
I need to do a 301 redirect to something like /%postname%/ or /%postname%-%post_id%/, or in a worst case senario, something like this:
%postname%-fnw%post_id%_%hour%%minute%%second%.php
I don't know how to write rewrite expressions. This is what I currently have now, but it's not working:
RedirectMatch 301 ^/([0-9]{4})/([0-9]{2})/([0-9]{2})/fnw(\d+)_%hour%%minute%%second%.php$ http://floridanewswire.com/?p=$4

Answer 1

%hour%%minute%%second% won't work in .htaccess, as this is meta information known only to WordPress. Instead, try replacing it with a rule that matches six digits, such as \d{6}
Also, you should remove unnecessary capture groups, escape forward sashes and dots, and use \d instead of [0-9].
Here is a fixed and simplified version of your expression:
RedirectMatch 301 ^\/\d{4}\/\d{2}\/\d{2}\/fnw(\d+)_\d{6}\.php http://floridanewswire.com/?p=$1
You should be able to change your permalinks to a cleaner structure on the Settings > Permalinks admin menu and have the old permalinks redirected through this htaccess rule.