htaccess replace character in query and redirect

Question

I need to replace '_' to '+' in query string than redirect:

site.com/abc_def/

to

site.com/search.php?q=abc+def

I tried this

RewriteRule ^([^/]+)/((.*)\_(.*))?$ /search.php?q=$1+$2 [R=301,L]

Answer 1

These are 2 rules that should work for you:

RewriteEngine On

# first replace _ by + recursively
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^_]*)_(.*)$ /$1+$2 [L]

# once all _s are gone, rewrite to /search.php?q=<search>
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^_]+)$ /search.php?q=$1 [L,QSA]