Exit batch script from inside a function

Question

I have a problem with my batch file. It builds several programs automatically by doing something like this:

• set some compilation flags
• run \'gmake all

Answer 1

Using a fatal syntax error, as jeb demonstrates, does kill all batch processing, but it also has a nasty side effect - environment changes after SETLOCAL are preserved, even though they are supposed to be discarded via implicit ENDLOCAL when batch processing ends. See my DosTips post SETLOCAL continues after batch termination! for more information.

Based on information at Why does a non-interactive batch script think I've pressed control-C?, I have discovered a clean way to exit all batch scripting from within a CALLed routine or script, and all changes after SETLOCAL are properly discarded.

@echo off
setlocal
set test=AFTER main SETLOCAL
call :sub
echo returning from main  NEVER REACHED
exit /b

:sub
setlocal
set test=AFTER sub SETLOCAL
set test
call :ExitBatch
echo returning from sub2 NEVER REACHED
exit /b


:ExitBatch - Cleanly exit batch processing, regardless how many CALLs
if not exist "%temp%\ExitBatchYes.txt" call :buildYes
call :CtrlC <"%temp%\ExitBatchYes.txt" 1>nul 2>&1
:CtrlC
cmd /c exit -1073741510

:buildYes - Establish a Yes file for the language used by the OS
pushd "%temp%"
set "yes="
copy nul ExitBatchYes.txt >nul
for /f "delims=(/ tokens=2" %%Y in (
  '"copy /-y nul ExitBatchYes.txt ExitBatchYes.txt
popd
exit /b

Here is sample output of running the above test.bat. You can see that the script never returned from the :ExitBatch call, and the test variable definition has been properly discarded once batch processing terminates.

C:\test>test.bat
test=AFTER sub SETLOCAL

C:\test>set test
Environment variable test not defined

C:\test>

The :ExitBatch routine can be put into its own ExitBatch.bat script and placed somewhere within your PATH such that it can be conveniently used by any batch script.

@echo off
:ExitBatch - Cleanly exit batch processing, regardless how many CALLs
if not exist "%temp%\ExitBatchYes.txt" call :buildYes
call :CtrlC <"%temp%\ExitBatchYes.txt" 1>nul 2>&1
:CtrlC
cmd /c exit -1073741510

:buildYes - Establish a Yes file for the language used by the OS
pushd "%temp%"
set "yes="
copy nul ExitBatchYes.txt >nul
for /f "delims=(/ tokens=2" %%Y in (
  '"copy /-y nul ExitBatchYes.txt ExitBatchYes.txt
popd
exit /b

Important Update:

It is now possible to implement robust exception handling with pure batch. Not only can you throw an exception that can terminate all batch processing from any CALL level, but you can also catch the exception at a higher level, excecute special exception handling cleanup code, and resume processing, or continue to exit via another throw! See Does Windows batch support exception handling? for more info.