1. Login as "postgres" (SuperUser) to start using database:

      # su - postgres

   2. Create a new database:

      $ createdb mydb

   3. Drop database:

      $ dropdb mydb

   4. Access database:

      $ psql mydb

   5. Get help:

      mydb=# \h

   6. Quit:

      mydb=# \q

   7. Read command from file:

      mydb=# \i input.sql

   8. To dump a database:

      $ pg_dump mydb > db.out

   9. To reload the database:

      $ psql -d database -f db.out

  10. Dump all database:

      # su - postgres
      # pg_dumpall > /var/lib/pgsql/backups/dumpall.sql

  11. Restore database:

      # su - postgres
      # psql -f /var/lib/pgsql/backups/dumpall.sql mydb

  12. Show databases:

      #psql -l
      or
      mydb=# \l;

  13. Show users:

      mydb=# SELECT * FROM "pg_user";

  14. Show tables:

      mydb=# SELECT * FROM "pg_tables";

  15. Set password:

      mydb=# UPDATE pg_shadow SET passwd = 'new_password' where usename = 'username';

  16. Clean all databases (Should be done via a daily cron):

      $ vacuumdb --quiet --all