Add line to INSTALL to ensure IP Address is set in /etc/hosts

[paulc-fugro]

The /etc/hosts file must have an entry for the host name and the actual IP address of the server.

Otherwise pbs_mom and pbs_comm fail to start silently.

$ hostname
DataServer
$ ifconfig
enp6s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 143.54.134.132  netmask 255.255.255.0  broadcast inet 143.54.134.255
$ cat /etc/hosts
127.0.0.1	localhost
#127.0.1.1	DataServer # Default setting, pbs_mom won't start
143.54.134.132 DataServer # Actual server IP and name

I'm on Ubuntu 20.04