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psql -U postgres -tA -c 'SELECT datname FROM pg_database' | sort
db=... ; pghost=localhost psql -U postgres -h $pghost -t -A -c "SELECT datname, tup_inserted, tup_updated, tup_deleted FROM pg_stat_database WHERE datname='$db';"
psql -U postgres -t -c 'SELECT datname, pg_size_pretty(pg_database_size(datname)) AS size FROM pg_database' | sort
or
psql -U postgres -t -c "SELECT datname, format('%8s GB.', pg_database_size(datname)/1000000) FROM pg_database" | sort