SysIII/usr/src/man/man1/wall.1m

.TH WALL 1M
.SH NAME
wall \- write to all users
.SH SYNOPSIS
.B /etc/wall
.SH DESCRIPTION
.I Wall\^
reads its standard input until an end-of-file.
It then sends this message to all currently
logged in users preceded by
``Broadcast Message from ...''.
It is used to warn all users,
typically prior to shutting down the system.
.PP
The sender should be super-user to override
any protections the users may have invoked.
.SH FILES
/dev/tty\(**
.SH "SEE ALSO"
mesg(1), write(1).
.SH DIAGNOSTICS
``Cannot send to ...'' when the open on
a user's tty file fails.