v7 man page for write

WRITE(1)						      General Commands Manual							  WRITE(1)

NAME
       write  -  write to another user

SYNOPSIS
       write user [ ttyname ]

DESCRIPTION
       Write copies lines from your terminal to that of another user.  When first called, it sends the message

	    Message from yourname yourttyname...

       The recipient of the message should write back at this point.  Communication continues until an end of file is read from the terminal or an
       interrupt is sent.  At that point write writes `EOT' on the other terminal and exits.

       If you want to write to a user who is logged in more than once, the ttyname argument may be used to indicate the appropriate terminal name.

       Permission to write may be denied or granted by use of the mesg command.  At the outset writing is allowed.  Certain commands, in  particu-
       lar nroff and pr(1) disallow messages in order to prevent messy output.

       If the character `!' is found at the beginning of a line, write calls the shell to execute the rest of the line as a command.

       The  following  protocol  is suggested for using write: when you first write to another user, wait for him to write back before starting to
       send.  Each party should end each message with a distinctive signal--(o) for `over' is conventional--that the other may	reply.	 (oo)  for
       `over and out' is suggested when conversation is about to be terminated.

FILES
       /etc/utmp to find user
       /bin/sh	      to execute `!'

SEE ALSO
       mesg(1), who(1), mail(1)

																	  WRITE(1)