title: Wall (Unix)
text: # Wall (Unix)
  
  wall (an abbreviation of write to all) is a Unix command-line utility that displays the contents of a computer file or standard input to all logged-in users. It is typically used by root to send out shutting down message to all users just before poweroff.
  
  ## Invocation
  
  wall reads the message from standard input by default when the filename is omitted. This is done by piping the output of the echo command:
  
  The message may also be typed in much the same way cat is used: invoking wall by typing wall and pressing ↵ Enter followed by a message, pressing ↵ Enter and Ctrl+D:
  
  Using a here-string:
  
  Reading from a file is also supported:
  
  All the commands above should display the following output on terminals that users allow write access to (see mesg(1)):
  
  