wall
—
write a message to users
wall
displays the contents of file
or, by default, its standard input, on the terminals of all currently logged
in users.
Only the super-user can write on the terminals of users who have
chosen to deny messages or are using a program which automatically denies
messages.
-g
- Send messages to users in this group. This option may be specified
multiple times, and any user in any of the specified groups will receive
the message.
A wall
command appeared in
Version 7 AT&T UNIX. Support for
-g
was added in NetBSD 2.0
(from OpenBSD 2.0).