.Use of OS native command
      Select option 6 on MENU screen.                     Chapter-(2)
      Or using DOS command prefix(>) create child Shell   Chapter-(5)

      If environment valiable such as PATH is required
      Use SET/EXPort command.
      ::xe.env is read to set environment variable at xe start if exist.
      if xe___.env(___:os type, ex. xewin.env) is exist this
      is used as alternative.

      For wxe, another process:xesyscmd console application executes the cmd.
      If the cmd requires user interaction, wxe enter to wait cmd response.
      Use Ctrl+C on the command prompt:xesyscmd to break wait.
      grep cmd may cause wait for the reserved filename such as AUX,COMn.
      Use Ctr+C also in that case.