Linux Messaging Commands

It's embarrassing but I keep forgetting commands to communicate with other users logged inside the Linux server. So, I'm writing it all here for me.

• wall - broadcast to all logged in users.  This is the only one I always remember.
• write - sends a message to the specific user.
• tty - displays the ttyname of the users among other things.
• When writing a message, input, Ctrl+C, or Ctrl+D sends the message.