mesg(1)

NAME
     mesg - permit or deny messages

SYNOPSIS
     mesg [ n ] [ y ]

DESCRIPTION
     Mesg with argument n forbids messages via write and talk(1)  by  revoking
     non-user  write  permission on the user's terminal.  Mesg with argument y
     reinstates permission.  All by itself, mesg  reports  the  current  state
     without changing it.

FILES
     /dev/tty*

SEE ALSO
     write(1), talk(1).

DIAGNOSTICS
     Exit status is 0 if messages are receivable, 1 if not, 2 on error.