wall(1M)                                                           wall(1M)


   NAME
         wall - write to all users

   SYNOPSIS
         /usr/sbin/wall

   DESCRIPTION
         wall reads its standard input until an end-of-file.  It then sends
         this message to all currently logged-in users preceded by:

               Broadcast Message from ...

         It is used to warn all users, typically prior to shutting down the
         system.

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

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

         wall will detect non-printable characters before sending them to the
         user's terminal.  Control characters will appear as a `^' followed by
         the appropriate ASCII character; characters with the high-order bit
         set will appear in meta notation. For example, `\003' is displayed as
         `^C' and `\372' as `M-z'.

   FILES
         /dev/tty*

   SEE ALSO
         mesg(1), write(1).

   NOTES
         ``Cannot send to ...'' when the open on a user's tty file fails.


















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