Exporting a CSV from Postgres
There are many ways to run a SQL statement in psql and export the result as a CSV. These are the two I usually reach for.
From a postgres repl:
\copy (SELECT * FROM users) TO 'users.csv' WITH (FORMAT csv, HEADER true);
Shell one-liner:
psql --csv -c "SELECT * FROM users;" --host 127.0.0.1 --port 5432 --user fred --dbname my_db > users.csv