Set RewriteBase to the current folder path dynamically

Question

Is there any way to set RewriteBase to the path current folder (the folder which the .htaccess file is in) relative to the host root?

I have a CMS and if I move it t

Answer 1

Building on anubhava's answer and Jon Lin's, here's what I just came up with for myself (haven't used this in production nor tested this extensively yet).

Let's use this example URL, where .htaccess is in current_folder:

http://localhost/path_to/current_folder/misc/subdir/file.xyz

Filesystem: /var/www/webroot/path_to/current_folder/.htaccess

Options +FollowSymLinks
RewriteEngine On
RewriteBase /

RewriteCond %{ENV:SUBPATH} ^$  # Check if variable is empty. If it is, process the next rule to set it.
RewriteRule ^(.*)$ - [ENV=SUBPATH:$1]
# SUBPATH is set to 'misc/subdir/file.xyz'

RewriteCond %{ENV:CWD} ^$
RewriteCond %{ENV:SUBPATH}::%{REQUEST_URI} ^(.*)::(.*?)\1$
RewriteRule ^ - [ENV=CWD:%2]
# CWD is set to '/path_to/current_folder/'

RewriteCond %{ENV:FILENAME} ^$
RewriteCond %{REQUEST_URI} ^.*/(.*)$
RewriteRule ^ - [ENV=FILENAME:%1]
# FILENAME is set to 'file.xyz'

# Check if /var/www/webroot/path_to/current_folder/misc/subdir/file.xyz exists.
# -f checks if a file exists, -d checks for a directory.
# If it exists, rewrite to /path_to/current_folder/misc/subdir/file.xyz and stop processing rules.
RewriteCond %{ENV:SUBPATH} ^.+$  # Ensure SUBPATH is not empty
RewriteCond %{DOCUMENT_ROOT}%{ENV:CWD}%{ENV:SUBPATH} -f [OR]
RewriteCond %{DOCUMENT_ROOT}%{ENV:CWD}%{ENV:SUBPATH} -d
RewriteRule ^.*$ %{ENV:CWD}%{ENV:SUBPATH} [END]

# Check if /var/www/webroot/path_to/current_folder/file.xyz exists.
# If it exists, rewrite to /path_to/current_folder/file.xyz and stop processing rules.
RewriteCond %{ENV:FILENAME} ^.+$
RewriteCond %{DOCUMENT_ROOT}%{ENV:CWD}%{ENV:FILENAME} -f [OR]
RewriteCond %{DOCUMENT_ROOT}%{ENV:CWD}%{ENV:FILENAME} -d
RewriteRule ^.*$ %{ENV:CWD}%{ENV:FILENAME} [END]

# Else, rewrite to /path_to/current_folder/index.html and stop processing rules.
RewriteRule ^.*$ %{ENV:CWD}index.html [END]

You can view the details of what's happening for yourself by using LogLevel alert rewrite:trace6 in your httpd.conf in apache, and then looking in your error.log.

Here's a bit more clarification on the following two lines, which I'd still found a bit confusing.

RewriteCond %{ENV:SUBPATH}::%{REQUEST_URI} ^(.*)::(.*?)\1$
RewriteRule ^ - [ENV=CWD:%2]

First off, the double colon :: is not an operator of any sort; it's just an arbitrary delimiter. The RewriteCond expands TestString %{ENV:SUBPATH}::%{REQUEST_URI} to the following:

misc/subdir/file.xyz::/path_to/current_folder/misc/subdir/file.xyz

Then our CondPattern ^(.*)::(.*?)\1$:

1. ^(.*):: matches misc/subdir/file.xyz::
2. \1 is the first capture group, misc/subdir/file.xyz
3. (.*?)\1$ becomes (.*?)misc/subdir/file.xyz$
4. Thus, our second capture group (.*?) matches the remaining /path_to/current_folder/

And our RewriteRule sets CWD to %2, which is the second capture group of CondPattern.