for the pre-login prompt text
sudo nano /etc/issue
(add the following text)
- X E R 0 C O N F -
___________________
OS build on : 2017-02-23
date || time : \d || \t
console @ host : \l @ \n
kernel version : \r
(leave two blank lines at the bottom)
(save and exit --> Ctrl-O, enter, Ctrl-X, enter)
for post-login/ssh-msg/motd text, edit the following file
sudo nano /etc/lsb-release
DISTRIB_ID=xer0conf
DISTRIB_RELEASE=2017.02.23
DISTRIB_CODENAME=tiger
DISTRIB_DESCRIPTION="xer0conf"
(save and exit --> Ctrl-O, enter, Ctrl-X, enter)
additionally comment out the sections in files
/etc/update-motd.d/10-help-text
/etc/update-motd.d/91-release-upgrade