mesg is a Unix command that sets or reports the permission other users have to write to your terminal using the talk and write commands. It is invoked as:
The 'y' and 'n' options respectively allow and disallow write access to your terminal. When invoked with no option, the current permission is printed.
Input redirection may be used to control the permission of another TTY. For example:
References
Mesg Wikipedia(Text) CC BY-SA