$ psql postgres
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

$nmap -p 5432 localhost

Starting Nmap 6.47 ( http://nmap.org ) at 2015-03-03 15:51 PST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00013s latency).
PORT     STATE  SERVICE
5432/tcp closed postgresql

Nmap done: 1 IP address (1 host up) scanned in 0.02 seconds

$ lunchy stop postgres
$ lunchy start postgres