htaccess redirect for permalinks

[Gemini23]

Can anyone advise the correct code to add to htaccess if changing the permalink structure? thanks in advance.
Wordpress installation is in the root not in a folder.

OLD/CURRENT (Custom) PERMALINK (with 'Category base as 'shows')
/news/%post_id%/%postname%/

NEW (Custom) PERMALINK (with no Category base)
/%category%/%postname%/

[seoskunk]

I think because each post has the post id and the category has changed as well your going to need to set up individual redirects for each post. I wouldn't use .htaccess I would use a Redirect plugin for wordpress that accepts csv files like this one [en-gb.wordpress.org...]

Here what I would do:
1. download the sitemap of all the urls posts in existing format. Add it to column one of your csv file
2. in column 2 map the new url for each post in the csv file
3. upload - job done

[phranque]

if you don't want to rely on a plugin for this, you could easily add an internal rewrite so that all requests for the /news/... paths are sent to a script that handles the redirect responses using the same csv file described by seoskunk.