When you need to send a real-time message to everyone, you can use the write all or wall command. It is normally used when there is a need to send an urgent message to everyone who is currently logged onto the system. I use it sparingly because it can be somewhat annoying to the enduser and you want users to pay attention to it. It sends the message immediately to the console. Here is its syntax.
This message is just for illustration purposes and hardly constitutes an emergency.
# wall
I hope everyone had a great and safe 4th of July weekend.
control+d