Using Apache htaccess file to change URL to lowercase

Question

How can I modify my .htaccess file on Apache to do the following:

"If the URL ends in .aspx, rewrite the entire URL to lowercase."

Backstory: I recently migrated a website from ASPX hosting to Linux/Apache hosting. There are some old URLs in the wild (marketing materials), and I need to make sure that those URLs still work; Windows web servers are not case-sensitive but Linux web servers are.

Thanks in advance.

Answer 1

You need to define a rewrite map which can only be done in server/vhost config files, not in htaccess files. You'll need to add something like:

RewriteMap lc int:tolower

Then in your htaccess file, you can create a rule like:

RewriteCond %{REQUEST_URI} [A-Z]
RewriteRule ^(.*\.aspx)$ ${lc:$1} [L,NC]

This will check that there are capital letters in the URI, then apply the map which turns everything into lowercase letters.

Answer 2

If you are not on a shared hosting environment and happy to enter the rules directly into your Apache configuration you can use mod_rewrites RewriteMap directive to do the lowercase conversion:

RewriteMap lc int:tolower
RewriteRule (.*?[A-Z]+.*) ${lc:$1} [R]

For more information on this see the Apache manual: Redirect a URI to an all-lowercase version of itself. Although it is noted there that it is recommended to use mod_speling instead of this rewrite rule.

with Apache rewrite and PHP: Taken from here

.htaccess

RewriteEngine on
RewriteBase /

# force url to lowercase if upper case is found
RewriteCond %{REQUEST_URI} [A-Z]
# ensure it is not a file on the drive first
RewriteCond %{REQUEST_FILENAME} !-s
RewriteRule (.*) rewrite-strtolower.php?rewrite-strtolower-url=$1 [QSA,L]

rewrite-strtolower.php

<?php
if(isset($_GET['rewrite-strtolower-url'])) {
    $url = $_GET['rewrite-strtolower-url'];
    unset($_GET['rewrite-strtolower-url']);        
    $params = strtolower(http_build_query($_GET));
    if(strlen($params)) {
        $params = '?' . $params;
    }
    header('Location: http://' . $_SERVER['HTTP_HOST'] . '/' . strtolower($url) . $params, true, 301);
    exit;
}
header("HTTP/1.0 404 Not Found");
die('Unable to convert the URL to lowercase. You must supply a URL to work upon.');

Setup up the rewrite module
Check if the incoming URL contains any uppercase letters
Ensure that the incoming URL does not refer to a file on disk (you may want to host a file with upper case letters in its name - something like a PDF file that a client has uploaded through the CMS you have supplied them for instance)
Send all the requests that match aforementioned rules are then rewritten to our script that will do the actual conversion to lowercase work.
The only thing to note here is the QSA modifier, which makes sure all the GET "variables" are passed onto the script

Next up is the little snippet of PHP that does all the work!
This is a file called rewrite-strtolower.php in the same directory as your .htaccess file mentioned above.