Let’s say you have a fairly complicated build structure, with multiple batch files that fire off different aspects of the build (even if, at the end of the day, they just call ant).

And let’s assume that for various historical reasons, these batch files encapsulate their environment variables using SETLOCAL and ENDLOCAL.

At first glance, this is a pretty cool way to scope out your environment variables. But then, you find out that Hudson determines if a build has succeeded or failed by looking at the %ERRORLEVEL% environment variable. If it is not 0, the build has failed.

Uh oh. Your build is failing, but the moment ENDLOCAL is called, %ERRORLEVEL% is set back to its previous value, which, most likely, will be 0.

Given this situation, how do you get the %ERRORLEVEL% back up to Hudson? Well, don’t call ENDLOCAL. Instead use:

EXIT %ERRORLEVEL%

at the end of your batch file. This works because there’s an implicit ENDLOCAL at the end of your batch file, and EXIT will return the ERRORLEVEL as the exit value.