mod rewrite - How does RewriteBase work in .htaccess

Question

I have seen this in a few .htaccess examples

RewriteBase /

It appears to be somewhat similar in functionality to the <base href=""> of HTML.

I believe it may automatically prepend its value to the beginning of RewriteRule statements (possibly ones without a leading slash)?

I could not get it to work properly. I think it's use could come in very handy for site portability, as I often have a development server which is different to a production one. My current method leaves me deleting portions out of my RewriteRule statements.

Can anyone explain to me briefly how to implement it?

Thanks

Answer 1

In my own words, after reading the docs and experimenting:

You can use RewriteBase to provide a base for your rewrites. Consider this

# invoke rewrite engine
    RewriteEngine On
    RewriteBase /~new/

# add trailing slash if missing
    rewriteRule ^(([a-z0-9-]+/)*[a-z0-9-]+)$ $1/ [NC,R=301,L]

This is a real rule I used to ensure that URLs have a trailing slash. This will convert

http://www.example.com/~new/page

to

http://www.example.com/~new/page/

By having the RewriteBase there, you make the relative path come off the RewriteBase parameter.