log in on psql console:
sudo -u postgres psql postgres
\q- quit ini console
\l - databases
\c mydb - use this db
\dt - tables
\d my mytable - show columns in mytable
log in on psql console:
sudo -u postgres psql postgres
\q- quit ini console
\l - databases
\c mydb - use this db
\dt - tables
\d my mytable - show columns in mytable