Convert and redirect URL in uppercase to lowercase using .htaccess

Question

I would like to redirect a URL with uppercase characters http://localhost/A/B to a lowercase version http://localhost/a/b using the .htaccess file.

Using regex I can capture A and B but is it possible to convert them to lowercase?

Answer 1

In .htaccess

<IfModule mod_speling.c>
CheckSpelling on
</IfModule>

Tested, works, if you have the mod_speling enabled.

Or, in a serverwide httpd.conf:

RewriteEngine On
RewriteMap  lc int:tolower
RewriteCond %{REQUEST_URI} [A-Z]
RewriteRule (.*) ${lc:$1} [R=301,L]

From: http://www.chrisabernethy.com/force-lower-case-urls-with-mod_rewrite/

Answer 2

If you are on Apache 2.4 then in .htaccess you can use mod_rewrite with an Apache expression in a RewriteCond directive to make use of the tolower() function. (You no longer need access to the server config to create a rewrite map.)

For example, the following will need to go near the top of your root .htaccess file:

RewriteEngine On

RewriteCond expr "tolower(%{REQUEST_URI}) =~ /(.*)/"
RewriteRule [A-Z] %1 [R=301,L]

This redirects/corrects any URL containing uppercase letters to the same - all lowercase - URL.

The RewriteRule pattern [A-Z] simply checks there is at least one uppercase letter in the requested URL-path. The RewriteCond directive then calls the tolower() function on the URL-path (REQUEST_URI server variable) the result of which is then effectively captured using the regex /(.*)/.

The %1 backreference in the substitution string then holds the result of the tolower() function call (as stored by the capturing group in the preceding condition), ie. the lowercase'd URL-path. Notably, this includes the slash prefix.

Test first with a 302 (temporary) redirect to avoid potential caching issues and only change to a 301 (permanent) when you are sure it's working OK. 301s are cached persistently by the browser so can making testing problematic.

Answer 3

RewriteEngine On
RewriteBase /

# If there are caps, set HASCAPS to true and skip next rule
RewriteRule [A-Z] - [E=HASCAPS:TRUE,S=1]

# Skip this entire section if no uppercase letters in requested URL
RewriteRule ![A-Z] - [S=28]

# Replace single occurance of CAP with cap, then process next Rule.
RewriteRule ^([^A]*)A(.*)$ $1a$2
RewriteRule ^([^B]*)B(.*)$ $1b$2
RewriteRule ^([^C]*)C(.*)$ $1c$2
RewriteRule ^([^D]*)D(.*)$ $1d$2
RewriteRule ^([^E]*)E(.*)$ $1e$2
RewriteRule ^([^F]*)F(.*)$ $1f$2
RewriteRule ^([^G]*)G(.*)$ $1g$2
RewriteRule ^([^H]*)H(.*)$ $1h$2
RewriteRule ^([^I]*)I(.*)$ $1i$2
RewriteRule ^([^J]*)J(.*)$ $1j$2
RewriteRule ^([^K]*)K(.*)$ $1k$2
RewriteRule ^([^L]*)L(.*)$ $1l$2
RewriteRule ^([^M]*)M(.*)$ $1m$2
RewriteRule ^([^N]*)N(.*)$ $1n$2
RewriteRule ^([^O]*)O(.*)$ $1o$2
RewriteRule ^([^P]*)P(.*)$ $1p$2
RewriteRule ^([^Q]*)Q(.*)$ $1q$2
RewriteRule ^([^R]*)R(.*)$ $1r$2
RewriteRule ^([^S]*)S(.*)$ $1s$2
RewriteRule ^([^T]*)T(.*)$ $1t$2
RewriteRule ^([^U]*)U(.*)$ $1u$2
RewriteRule ^([^V]*)V(.*)$ $1v$2
RewriteRule ^([^W]*)W(.*)$ $1w$2
RewriteRule ^([^X]*)X(.*)$ $1x$2
RewriteRule ^([^Y]*)Y(.*)$ $1y$2
RewriteRule ^([^Z]*)Z(.*)$ $1z$2

# If there are any uppercase letters, restart at very first RewriteRule in file.
RewriteRule [A-Z] - [N]

RewriteCond %{ENV:HASCAPS} TRUE
RewriteRule ^/?(.*) /$1 [R=301,L]