For `knife`, the default is ~/.chef/knife.rb. For `chef-client`, the default is /etc/chef/client.rb. For `chef-solo`, the default is /etc/chef/solo.rb.
"`raise` is better. The various `fatal!` methods in Chef aren’t intended to halt a Chef run, and they call `exit` which raises a SystemExit exception. Depending on where you do this, chef-client may actually exit when not intended."