so you have your fresh new Ubuntu system and you log in via ssh to be greeted with

“Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

bla bal bla”

so you fire up vim and change the good ol /etc/motd to sometime a little more along the lines of threating anyone who misuses the system with the wrath of IT.

super your new MOTD works great untill you reboot the system. heres a little secret about Ubuntu notice the first line of the MOTD when you logd in the first time? The line about the kernel version and other system information? Well thats all there because Ubuntu generates the /etc/MOTD file during system startup so any changes you make to this file will be lost on the next reboot. Solution? Ubuntu generates the first line then appends the conents of /etc/MOTD.tail to the end and saves it as /etc/MOTD.

so to use your new MOTD you need to save your message to /etc/MOTD.tail