Export SQL results to file

\copy (select username from auth_user order by date_joined desc limit 10000) to 'latest-users.csv' with csv;

Export database via shell

$ pg_dump -U username -h hostname databasename > dump.sql

List databases

\l

Switch databases

\c dbname username

Execute commands from file

\i filename

Get help for specific command

\h truncate

Show running queries

SELECT pid, age(clock_timestamp(), query_start), usename, query 
FROM pg_stat_activity 
WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%' 
ORDER BY query_start desc;