wall(1M)

wall -- write to all users

Synopsis

/usr/sbin/wall [-g group] [file]

Description

The wall command reads the named file, or, if no filename appears, it reads the standard input until an end-of-file. It then sends this message to all currently logged-in users preceded by:

   Broadcast Message from source . . .

The command is used to warn all users, typically before shutting down the system. When the -g option is specified, the command uses the /etc/group file to determine which logged in users should receive the message. When the -g option is specified, the message is sent only to members of the specified group, instead of to all users.

The sender must be a privileged user to override any protections the users may have invoked [see mesg(1)].

wall runs setgid [see setuid(2)] to the group ID tty, to ensure write permissions on other user's terminals.

The wall command processes supplementary code set characters according to the locale specified in the LC_CTYPE environment variable [see LANG on environ(5)]. It detects non-printable characters before sending them to a user's terminal. Control characters appear as a ``^'' followed by the appropriate ASCII character; for example, ``\003'' is displayed as ``^C''.

Files

/dev/term/*
/etc/group
/usr/lib/locale/locale/LC_MESSAGES/uxcore: language-specific message file [See LANG on environ(5).]

Diagnostics

UX:wall:ERROR:Cannot send to . . .: The open on a user's tty file failed.

References

mesg(1), write(1)