我已用sudo service postgresql status检查服务器状态
● postgresql.service - PostgreSQL RDBMS
Loaded: loaded (/lib/systemd/system/postgresql.service; enabled; vendor preset: enabled)
Active: active (exited) since Tue 2019-06-11 13:51:09 IST; 15min ago
Process: 929 ExecStart=/bin/true (code=exited, status=0/SUCCESS)
Main PID: 929 (code=exited, status=0/SUCCESS)
CGroup: /system.slice/postgresql.service
Jun 11 13:51:07 ISW114 systemd[1]: Starting PostgreSQL RDBMS...
Jun 11 13:51:09 ISW114 systemd[1]: Started PostgreSQL RDBMS.
Jun 11 13:56:53 ISW114 systemd[1]: Started PostgreSQL RDBMS.
它工作正常，但是当我尝试使用psql时，出现如下错误
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?