Fills **File_Command_lineEdit** Widget.

def __File_Command_lineEdit_set_ui(self):
        """
        Fills **File_Command_lineEdit** Widget.
        """

        # Adding settings key if it doesn't exists.
        self.__settings.get_key(self.__settings_section, "file_command").isNull() and \
        self.__settings.set_key(self.__settings_section, "file_command", self.__file_command)

        file_command = self.__settings.get_key(self.__settings_section, "file_command").toString()
        LOGGER.debug("> Setting '{0}' with value '{1}'.".format("File_Command_lineEdit",
                                                                file_command))
        self.__file_command = file_command
        self.File_Command_lineEdit.setText(file_command)