@echo off
:: This batch file checks if a drive letter is mapped or not.
:: It exits with 0 if the drive is mapped and 1 if it isn't.
SET gdrive=G
if exist %gdrive%:\ (
    	echo The %gdrive% drive is mapped Exiting with 0 to continue running.
	exit /b 0
)
echo The %gdrive% drive is NOT mapped. Exiting with 1 to restart.
exit /b 1