Manual Pages  — WALL

wall – write a message to users

SYNOPSIS DESCRIPTION SEE ALSO HISTORY BUGS

wall [-g group] [file]

The wall utility 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 PWB UNIX.

The sender's LC_CTYPE setting is used to determine which characters are safe to write to a terminal, not the receiver's (which wall has no way of knowing).