Command: ctty

  Changes TTY (console), the terminal device used to control your system.


  CTTY device
  CTTY [/?]


  device  The terminal device you want to use. Valid devices are prn,
          lpt1, lpt2, lpt3, con, aux, com1, com2, com3, com4, NUL.
  /?      Shows the help.


  CTTY device
  With this command the console device can be changed. A console device
  performs all basic input and output operations. This change is more
  complete than IO-redirections, because latter one might not catch all
  output, for instance the error messages. See example 3 below.
  Because the console is a bidirectional virtual device, meaning it is
  to perform input and output, the specified device must not be a
  unidirectional device, such as PRN.
  To specify a second argument on the command line of FreeCOM has the
  same effect.
  Attention: This command is to effect the whole system, not only
  FreeCOM itself; so the effect of CTTY does not only depend on the
  implementation status of FreeCOM, but on the DOS kernel, too.
  Also, some programs access the screen or keyboard directly, rather
  than using the DOS functions; these programs are not effected by CTTY.
  CTTY is a command internal to and needs no other file
  in order to work.


Example 1:
    CTTY aux
  Changes the console to the AUX: device, which is usually the first
  serial communication port COM1:. If this line is connected to a
  terminal or a terminal emulator, the system can be controlled from
  the terminal by now.
Example 2:
    CTTY nul
  any command sequence
    CTTY con
  The first command discards any output. If a program attempts any
  input operation, it gets none. Some programs may not handle such
  situation correctly.
  So, any output, even error messages, are discarded during the command
  The second command changes the console back to the screen/keyboard
  Example 3:
  To display a string onto screen or read from keybord the usual
  I/O-redirections may be used, for instance:
    ECHO This line appears on the screen >CON
    This PAUSE command will get its input even within the "CTTY nul"

See also:

  Copyright © 2004 Robert Platt, updated 2011 and 2022 by W. Spiegl.

  This file is derived from the FreeDOS Spec Command HOWTO.
  See the file H2Cpying for copying conditions.