rconMessager is a little script to send rcon messages to a game server in defined intervals.
Your need mcrcon installed on your system https://github.com/Tiiffi/mcrcon (it should be on the PATH, say... /usr/bin)
My comrade Taran is making a PowerShell version for you windows lovers ;) https://github.com/tarAn-OD/PoWERSHELL-MOTD-ADMIN-MESSAGES
All the info you need to use it is on the script comments!
