"permission denied" for pg_dump output file
It looks like your pg_dump is working fine, but it is having problems opening the output file as the sudo user. Just guessing, but, if you do the redirection as the user (presumably the one running the pg_dump command) id, that should do it, that is:
sudo -u user_name pg_dump dbName > /home ..../someWhere/db.sql
Using this technique your pg_dump will run as the postgres user (assuming that is who user_name is) and the file being written in /home... will be written using the permission of the user running the command (this user might have different permissions than the postgres user).
try pg_dump from psql command-line as below:
postgres=# \! pg_dump dbName -f /home ..../someWhere/db.sql
Do it from psql command line like below
-bash-4.1$ pg_dump -Fp dbName -f /home ..../someWhere/db.sql &-F selects the format of the output in which p is Output a plain-text SQL script file
and & at the end will run your backup in the background.