wall(1M) MISC. REFERENCE MANUAL PAGES wall(1M)
NAME
wall - write to all users
SYNOPSIS
/usr/sbin/wall
DESCRIPTION
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.
The sender must be super-user to override any protections
the users may have invoked [see mesg(1)].
wall runs setgid() [see setuid(2)] to the group ID tty, in
order to have write permissions on other user's terminals.
wall will detect non-printable characters before sending
them to the user's terminal. Control characters will appear
as a `^' followed by the appropriate ASCII character; char-
acters with the high-order bit set will appear in meta nota-
tion. For example, `\003' is displayed as `^C' and `\372' as
`M-z'.
FILES
/dev/tty*
SEE ALSO
mesg(1), write(1).
NOTES
``Cannot send to ...'' when the open on a user's tty file
fails.
Last change: Essential Utilities 1