[gpadmin@test-4 ~]$ gpconfig -c shared_buffers -v '128MB'
20200506:08:54:37:3461042 gpconfig:test-4:gpadmin-[ERROR]:-could not connect to server: Connection refused
	Is the server running on host "localhost" (::1) and accepting
	TCP/IP connections on port 7456?
could not connect to server: Connection refused
	Is the server running on host "localhost" (127.0.0.1) and accepting
	TCP/IP connections on port 7456?