public TCL.CompletionCode cmdProc( Interp interp, TclObject[] argv )
    {
      string dirName;

      if ( argv.Length > 2 )
      {
        throw new TclNumArgsException( interp, 1, argv, "?dirName?" );
      }

      if ( argv.Length == 1 )
      {
        dirName = "~";
      }
      else
      {

        dirName = argv[1].ToString();
      }
      if ( ( JACL.PLATFORM == JACL.PLATFORM_WINDOWS ) && ( dirName.Length == 2 ) && ( dirName[1] == ':' ) )
      {
        dirName = dirName + "/";
      }

      // Set the interp's working dir.

      interp.setWorkingDir( dirName );
      return TCL.CompletionCode.RETURN;
    }