Migrate Postgresql users to another server and RDS

postgres-user-migration.txt

-- Export the users
pg_dumpall -g > users.sql

-- Importing to another PostgresSQL
awk '/CREATE/' users.sql > migrate.sql

-- Import to RDS; It won't support super user and replication roles. But we can grant minimal superuser with rds_superuser
psql -h localserver -d postgres -t -c"select 'grant rds_superuser to '||rolname ||';' from pg_roles where rolsuper='t';" -P "footer=off" >> migrate.sql
sed -i -e's/NOSUPERUSER//g; s/SUPERUSER//g; s/NOREPLICATION//g; s//REPLICATION/g' migrate.sql
psql -h rds-endpoint -U adminuser -d postgres < migrate.sql