I am planning to make clean URLs with htaccess as in php url routing question .
I would change from:
/movies/index.php?id=iron_man
/movies/iron_man
But the old-style links are already on the interwebs. What would happen when I access
/movies/index.php?id=iron_man
when htaccess is in place?
Do I have to be concerned with identifying and redirecting the old-sytle links, when a request appears? If so, how do I do it?
And can I set it to 301 redirects (which avoids SEO penalties)?
Yes you should be concerned or you will lose value from links pointing to those URLs. You should definitly spend time to redirect using a 301 header to the new URL using:
The easiest way it to let your old rewrite point to a script handling all movie redirects.