Comprehensive Rewrite Rules / Regular Expressions Guide?

[Jérôme Loyet]

2009/4/1 Ole Rehmsen <lists at ruby-forum.com>:
> Hey everyone,
>
> I want to modify some rewrites I currently have in my nginx.conf, but I
> could not find proper documentation of the available operators and
> language constructs to do so. Googling I found tons of people trying to
> convert rewrite rules from apache to nginx, but since I have never used
> apache, this is not very helpful to me. Is there some document
> explaining all supported operators for the regular expressions?
>
> For example, I have something like $host ~* "www" in my config, and from
> the context I can guess that ~* seems to check whether the left hand
> side contains the right hand side. But I did not find a proper
> specification in any regular expressions guides.

I think this should make the trick:

if ($host !~* "^www.exemple.de") {
  rewrite ^(.*)$ http://www.exemple.de$1 permanent;
}

>
> My current problem at the moment is that I want to say something like
> "if the domain used is not already www.example.de, than change it that
> way". I want that all example.com, example.org... are rewritten to read
> www.example.de. So I need to know wether there is a possibility to
> negate a condition, or something like "unless" or so. However, this is
> only one problem I have right now, I would very much like to understand
> the bigger picture and all the options I have in rewritting stuff. Is
> there a document listing those options?

http://wiki.nginx.org/NginxHttpRewriteModule
and
http://wiki.nginx.org/NginxHttpCoreModule#Variables