Regular Expression to fix broken URL's in Nginx - wordpress

Question

On my previous server that ran apache I had some htaccess rules that helped forward a certain pattern of URL's which were giving 404's to the fixed pattern.
Long time ago my URLS for my site were http://domainname/articlename and then I changed it to be http://domainname/category/articlename
Now the problem is the older links that google has are returning 404's and I want to intercept any URL that doesn't have a category and insert a fake category and then my wordpress installation can resolve the URL.
So I'm looking for a nginx solution to this problem which I presume will be in the config file somewhere that will take this URL
http://www.criticalhit.net/prey/ (which gives a 404)
and change it to
http://www.criticalhit.net/fixed/prey/
which then resolves properly.

Answer 1

Use a named location to perform the rewrite, although this simple rewrite can be accomplished efficiently using a return 301.
Place a regular expression location (after the PHP location block) to bypass excluded URLs. This does not need to include the static files which are served by the try_files statement.
For example:
root /path/to/root;
index index.php;
location / {
try_files $uri $uri/ #rewrite;
}
location #rewrite {
return 301 /category$request_uri;
}
location ~ \.php$ {
try_files $uri =404;
...
}
location ~ ^/(category|tags|feeds) {
try_files $uri $uri/ /index.php;
}
See this document for more.