4.0; xon, revision 4.0, 82/03/31.
XON -- Activate the Shell's -X flag.
usage:  XON


FORMAT

  XON


  XON turns on execution tracing. Just before each command is executed,
  its full pathname and arguments are written to the error output stream
  of the Shell. In Shell scripts, XON can be used to show the progress
  being made by the script, and can help debug Shell scripts by showing
  the actual arguments being passed to commands, after all Shell
  processing on them is complete.

  By default, execution tracing is off when a Shell is invoked.

  If XON is turned on in a Shell script, it remains on until that
  Shell script exits, or until over-ridden by a XOFF in a nested
  Shell script. When a Shell script exits, the state of execution
  tracing is returned to the state in effect just before the
  script was invoked.

  XON requires no arguments or options.


RELATED TOPICS

  More information is available.  Type:

    - HELP XOFF
      for details about turning execution tracing off.

    - HELP SH and HELP SHELL
      for details about the Shell command line interpreter.