\? #Help
\l # List of databases  in cluster
\l+ # List of databases have more information
\du # List of users
\db # List of tablespaces
\c $db $user #You are now connected to database $db as user $user.
\dt # List of relations
\d $table #Describe $table
\dn # List of schemas
\dn+ # List of schemas (with Size, Description)
\df # List of functions
\dv # List of
\ef $func_name # Describe $func_name  function
\timing on # Turn on timing
\timing off # Turn on timing
\i sequel.sql # Execute SQL script
\e #Hot edit SQL satement
\conninfo # Show connection Info
\! pwd # current folder
\! mkdir doc # make doc dir
\! ls
 

\H
select * from dept;
\o # Second \o will stop output as file

\H
select * from dept;
\o # Second \o will stop output as file

psql -f sequel.sql -d $database -U $user