change environmental variable in BATCH file

[Ziv Margolin]

Hi

I am trying to set new value for environmental variable BUILD_ID

My batch build is something like that:

BUILD_ID=dontKillMe

start -w c:\mydir\myprog.exe > c:\txt\resoult.txt

findstr c\:"PASS" c:\txt\resoult.txt

if errorlevel 0 (

echo "1"

)

what will be the correct 

Thank you