Unanswered: Could not open postmaster.pid: permission denied
So I have a NAS which has some disks connected via USB to it and on one of those disks I have my database directory. I also have a low power GuruPlug on which I wish to start up the postgresql server so I can use the databases on it.
Everything on my NAS is setup so I can access it's USB disks wirelessly, so I've mounted the necessary partition with this line.
I've solved it myself now. As it turns out, the problem was that while I had run chown on the PostgreSQL directory, the parent directories had a different owner than the one I used to mount it with. After changing the owner on the entire directory, I can now start the server.