A simple function and some commands to grant privileges to every table in a PostgreSQL database. * each file is a different method. You don't need need to use them all in conjunction.

grant_table_privilege_on_all_table_w_psql

Use the commands below to set privileges using the PSQL terminal commands.  

TABLES:
for tbl in `psql -qAt -c "select tablename from pg_tables where schemaname = 'public';" YOUR_DB` ; do  psql -c "alter table $tbl owner to NEW_OWNER" YOUR_DB ; done

SEQUENCES:
for tbl in `psql -qAt -c "select sequence_name from information_schema.sequences where sequence_schema = 'public';" YOUR_DB` ; do  psql -c "alter table $tbl owner to NEW_OWNER" YOUR_DB ; done

VIEWS:
for tbl in `psql -qAt -c "select table_name from information_schema.views where table_schema = 'public';" YOUR_DB` ; do  psql -c "alter table $tbl owner to NEW_OWNER" YOUR_DB ; done

grant_table_privilege_pg.sql

-- Function: user_management(text)

-- DROP FUNCTION user_management(text);

CREATE OR REPLACE FUNCTION user_management(text)
  RETURNS void AS
'BEGIN execute $1; END;'
  LANGUAGE plpgsql VOLATILE
  COST 100;
ALTER FUNCTION user_management(text)
  OWNER TO postgres;
COMMENT ON FUNCTION user_management(text) IS 'run this command to grant SELECT on all tables in the db.

select user_management('grant select on ' || tablename || ' to reader;') from pg_tables where schemaname = 'public';';