General Commands Manual
NAME wall — write a message to users
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.
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.
HISTORY A wall command appeared in Version 7 AT&T UNIX. Support for -g was added in NetBSD 2.0 (from OpenBSD 2.0).