Some random observations that may or may not be of use.
Are you making sure to reload PostgreSQL whenever you make a config change?
I also found pg_hba.conf on both folders /var/lib/pgsql/11/data/pg_hba.conf & /var/lib/pgsql/data/pg_hba.conf). I modified it as above and the script is not working even run from the command prompt.
To find out which pg_hba.conf file your running database is using run:
show all;
Then search for hba_file or view directly by:
select setting from pg_settings where name = 'hba_file';
You can verify your pg_hba.conf settings with (as user postgres):
select * from pg_hba_file_rules ;
# export HOSTNAME=hostname
# export USERNAME=postgres
# export DATABASE=postgres
# export PORT 5432
# pg_dump -v -p $PORT -U $USERNAME -d $DATABASE -f /tmp/postgresbakup.sql
Looks like you are missing the "=" between PORT and 5432
Cheers,
Steve