I can't get pg to shutdown or otherwise respond. I closed the cygwin console window and opened another (PG was working fine with the other window).
$ pg_ctl status pg_ctl: postmaster is running (pid: 1656) Command line was: /usr/bin/postmaster
$ pg_ctl stop -m immediate kill 1656: No such process waiting for postmaster to shut down........................ ......... failed pg_ctl: postmaster does not shut down