If you’re using the PostgreSQL command line interface (CLI), you can select the database while at the Postgres prompt by typing the following command:
\connect database name
Or:
\c databasename
You can now list tables within that database using the ‘\dt’ command and list all other databases with the ‘\l’ command.
If you are not at a PostgreSQL command prompt, but rather a Linux command prompt, you’d use the following command:
psql dbname