wall(1M)              UNIX System V(Essential Utilities)               wall(1M)


NAME
      wall - write to all users

SYNOPSIS
      /usr/sbin/wall [-g group] [filename . . .]

DESCRIPTION
      wall reads the named files or if no filenames appear, 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.

      If the -g option is given, the message is only sent to members of the
      specified group instead of all users.

      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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