mesg - control write access to your terminal
Mesg controls the access to your terminal by others.
It's typically used to allow or disallow other users to
write to your terminal (see write(1)).
Allow write access to your terminal.
Disallow write access to your terminal.
If no option is given, mesg prints out the current
access state of your terminal.
Mesg assumes that it's standard input is connected to
your terminal. That also means that if you are logged in
multiple times, you can get/set the mesg status of other
sessions by using redirection. For example
Miquel van Smoorenburg (email@example.com)
talk(1), write(1), wall(1)