alex-mctammanys-macbook:campus alexmctammany$ sudo mkdir -p /opt/local/var/db/postgresql84/defaultdb
alex-mctammanys-macbook:campus alexmctammany$ sudo chown postgres:postgres /opt/local/var/db/postgresql84/
alex-mctammanys-macbook:campus alexmctammany$ sudo su postgres -c '/opt/local/lib/postgresql84/bin/initdb -D /opt/local/var/db/postgresql84/defaultdb'
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.

The database cluster will be initialized with locale en_CA.UTF-8.
The default database encoding has accordingly been set to UTF8.
The default text search configuration will be set to "english".

fixing permissions on existing directory /opt/local/var/db/postgresql84/defaultdb ... initdb: could not change permissions of directory "/opt/local/var/db/postgresql84/defaultdb": Operation not permitted