How to use $request_body?

[witekfl at gazeta.pl]

On Mon, Oct 04, 2010 at 01:33:23PM +0400, Boris Dolgov wrote:
> On Mon, Oct 4, 2010 at 12:04, witekfl Gazeta.pl <witekfl at gazeta.pl> wrote:
> > Hi,
> > There is in config:
> > location / {
> >     root blabla;
> -     if ($request_body ~* (blabla|bebe)) {
> +     if ($request_body ~* "(blabla|bebe)") {
> >          return 404;
> >     }
> > }
> > nginx -t says invalid condition "$request_body".

I gave wrong example. There were spaces in original config.
Nevermind.

I'll answer myself.
References to $request_body must follow fastcgi_pass or proxy_pass, eg.
location / {
    root blabla;
    proxy_pass http://apache;
    if ($request_body ~* (blabla|bebe)) {
        return 404;
    }