following guidance from this post although it's an ubuntu build and I'm running Centos the issues are the same. An engineer here says that /usr/share/elasticsearch/bin/elasticsearch-systemd-pre-exec was removed from 6 so it will never work so I made the changes that there recommended against by the elastict team memeber in the origionally quoated post plus removed that line and my install started. I'm still having issues talking to it but I'm going to create a new thread for that as it's a fresh issue. For those who found this and then find the service starts but they keep getting connection refused, for me there was a elasticsearch.yml.rmpnew which I replaced my config file with, essentially it's just
path.data: /var/lib/elasticsearch
path.logs: /var/log/elasticsearch
which allowed me to interact on localhost, but I don't get responses when I try to add a host ip