Redirect URL ending in certain `variable=value` query string, to `URL?variable` (i.e., strip `=value`)

Question

I'm trying to create a 301-rewrite for URLs ending with ?amp=1 to nearly the same URL and query string, just stripping the value (=1).

Examples:

• https://example.com/?amp=1 should redirect to https://example.com/?amp
• https://example.com/page/?amp=1 should redirect to https://example.com/page/?amp

I've managed to get the RewriteCond right to match only URLs ending with ?amp=1, i.e.:

RewriteCond %{QUERY_STRING} ^/?amp=1$

but can't get the RewriteRule correct to go to the URL without the =1 value.

Answer 1

Your RewriteCond is incidentally valid but fundamentally wrong. For the URL https://example.com/?amp=1, the characters /? are not part of the %{QUERY_STRING} value, which is amp=1 in fact.
I said 'incidentally valid' because in your regex, / is neutralized by ?, so there is a match with amp=1.

To achieve your goal, in the simplest case, especially without the possibility of other variables in the query string, an Apache .htaccess file could include these directives:

# Tested with Apache httpd 2.4 on Debian 10
RewriteCond %{QUERY_STRING} ^amp=1$
RewriteRule (.*) /$1?amp [NE,R=301,L]