CTTY devicename

The CTTY internal command allows you to change the CONSOLE device from which
commands are entered and to which output is displayed.  Usually commands come
from the keyboard, and output goes to the screen. [Not supported in OS/2]

<devicename>  can be CON, COM1, COM2, or NUL, with an optional trailing ":".

  CTTY COM1			Would change command entry and output display
				from the current CONSOLE to the COM1 device.

  CTTY CON			Would reset command entry and output display
				back to the keyboard and screen.

  CTTY NUL			Would change entry and display to the NUL
				device. Useful only in BATCH files.

  CTTY > LOG.FIL		Would change output display (only) to be
				written to file LOG.FIL. Command entry would
				still come from the keyboard. CTTY < INPUT.FIL
				would similarly change command entry (only) to
				come from the file INPUT.FIL. [This does NOT
				work in DOS 4.0, or on some versions of DOS
				prior to 4.0.]
