WALL(8) Maintenance Procedures WALL(8)


wall - write to all users


/usr/sbin/wall [-a] [-g grpname] [-z zonename] [-Z] [filename]


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 ...

If filename is given, then the message is read in from that file.
Normally, pseudo-terminals that do not correspond to rlogin sessions are
ignored. Thus, when using a window system, the message appears only on
the console window. However, -a will send the message even to such
pseudo-terminals. Normally, wall sends messages to the current zone only,
from the global zone -Z will send messages to all nonglobal zones, and -z
will send messages to a specified nonglobal zone

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

The sender must be superuser to override any protections the users may
have invoked See mesg(1).

wall runs setgid() to the group ID tty, in order to have write
permissions on other user's terminals. See setuid(2).

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; characters with the high-order bit set
will appear in "meta" notation. For example, `\003' is displayed as `^C'
and `\372' as `M-z'.


The following options are supported:

Broadcast message to the console and pseudo-terminals.

-g grpname
Broadcast to the users in a specified group only, per the
group database (see group(5)).

-z zonename
Broadcast to the users in a specified zone only

Broadcast message to the console and pseudo-terminals of
all zones.


If the LC_* variables (LC_CTYPE, LC_TIME, LC_COLLATE, LC_NUMERIC, and
LC_MONETARY) are not set in the environment, the operational behavior of
wall for each corresponding locale category is determined by the value
of the LANG environment variable. See environ(7). If LC_ALL is set, its
contents are used to override both the LANG and the other LC_*
variables. If none of the above variables are set in the environment, the
"C" (U.S. style) locale determines how wall behaves.




mesg(1), write(1), setuid(2), attributes(7), environ(7)


wall displays ``Cannot send to ...'' when the open on a user's tty file

July 13, 1994 WALL(8)