Hi,

i am using a catchall host for proxying requests to an other server.

now i want to have that nginx writes a logfile for every domain that is called...

i tried
access_log /var/log/nginx/$host.access.log;

but $host is not parsed :-)

how can i get it working?

I have the exact same access_log directive in my catchall host config. It works. Perhaps the user under which nginx is running doesn't have write permission to /var/log/nginx on your file system.