Mod rewrite , much useful module in apache httpd web server. Although, we utilize it for rewriting the url , redirection, I just want to point out about a special flag which acts like a while loop.
So let’s say, you have a requirement that you want to replace some character or want to process mod rewrite rule , just like a do while loop, but you do not have any control over, how many times it can appear in url.
Example:-
https://example.com/test_underscore_replace_by_hyphen
So you want to replace each of the underscore by hyphen.
https://example.com/test-underscore-replace-by-hyphen
This is achieved by N [Next] flag in rewrite condition.
RewriteEngine on RewriteRule ^(.+)_(.+)$ $1-$2 [N]
question:- How to control, then number of loop iteration ?
RewriteEngine on RewriteRule ^(.+)_(.+)$ $1-$2 [N=10] #It means , iteration will be 10 times.
Imp-1 :- If you do not specify default looping is 32000 .
Imp-2 :- Controlling iteration in directory path as well.
Let’s say url is https://example.com/dir_1/dir_2/test_underscore_replace_by_hyphen
if you test this url against the above rule, it will not produce the desired result.
if you check error log , you will find the
“add path info postfix” line.
it means , mod_rewrite will iterate over request uri and search and it will add the path next to it. this will create a url that will not be valid.
Coming to point,
Add DPI [discardpath] flag
RewriteEngine on RewriteRule ^(.+)_(.+)$ $1-$2 [N,DPI] #It means , iteration will be 10 times. result will be https://example.com/dir-1/dir-2/test-underscore-replace-by-hyphen
