WALL(1) General Commands Manual WALL(1)
NAME
wallwrite a message to users
SYNOPSIS
wall
[-g group] [file]
DESCRIPTION
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.
SEE ALSO
HISTORY
A wall command appeared in Version 7 AT&T UNIX. Support for -g was added in NetBSD 2.0 (from OpenBSD 2.0).