How to write a url rewrite in nginx?

I want people type in http://www.myweb.com/like/1234456 will redirect to http://www.myweb.com/item.php?itemid=1234456

I wrote something like this in the config but it doesn't work.

location = ^~/like/ {
                rewrite ^1234456  ../likeitem.php?item=1234456break;
                return 403;
        }

this is just a test. I haven't used the $ matching yet.

I also restart my ngnix server but still.. it doesn't do the redirect.