wall(1)

NAME
     wall - write to all users

SYNOPSIS
     /sbin/wall [-g group] [msg_file]

DESCRIPTION
     wall reads msg_file (or its standard input if none specified) until an
     end-of-file.  It then sends this message to all currently logged-in users
     preceded by:

          Broadcast Message from ...

     If the -g option is used then only those users in the specified group as
     defined in the file /etc/group or the NIS group map are sent the message.
     The list of logged-on users is derived from the file /var/adm/utmp.

     It is used to warn all users, typically prior to shutting down the
     system.

     The sender must be super-user to override any protections the users may
     have invoked (see mesg(1)).

NOTE
     wall does not send messages to ftp users.

FILES
     /dev/*
     /var/adm/utmp

SEE ALSO
     mesg(1), write(1), who(1).

DIAGNOSTICS
     ``Cannot send to ...'' when the open on a user's tty file fails.