.htaccess variables

[tangaroa]

You can set variables inside an Apache .htaccess file. To copy directly from someone else's example:

 RewriteCond  %{REQUEST_URI}  ^/category_abc/ 
 RewriteRule .* - [E=cat_id:1] 

 RewriteCond  %{REQUEST_URI}  ^/category_def/ 
 RewriteRule .* - [E=cat_id:2]

 - The E= tells Apache we're creating a new ENV variable. 
 - The cat_id is the name of the variable we're creating 
 - The :x is the value of the variable (simple key : value syntax).

And from another example:

RewriteCond %{HTTP:Accept-Language} ^.*(de|es|fr|it|ja|ru|en).*$ [NC]
RewriteRule ^(.*)$ - [env=lang:%1]
Set lang var to URI
RewriteEngine On
RewriteBase /
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /(.+)/(de|es|fr|it|ja|ru|en)/\ HTTP/ [NC]
RewriteRule ^(.*)$ - [env=lang:%2]

Environment variables are referenced as %{ENV:varname}. How they are used is another story. There are places you can't use them.

# Make a variable for RewriteBase
RewriteCond "/base_dir/" ^(.*)$
RewriteRule ^(.*)$ - [E=RewriteBase:%1]
# Fails, causes an internal server error.
RewriteBase %{ENV:RewriteBase}

You can't do this either:

# RequestPrefix is a previously declared variable. 
RewriteCond %{REQUEST_URI} ^%{ENV:RequestPrefix}(.*)$
RewriteRule ^(.*)$ - [E=RequestSuffix:%1]

A quick web search finds someone claiming that rewrite condition patterns are compiled before variables are interpreted.