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windowsprocessbatch-fileexit-code

Check if process returns 0 with batch file

I want to start a process with a batch file and if it returns nonzero, do something else. I need the correct syntax for that.

Something like this:

::x.bat

@set RetCode=My.exe
@if %retcode% is nonzero
   handleError.exe

As a bonus, you may consider answering the following questions, please :)

  • How to write a compound statement with if?
  • If the application My.exe fails to start because some DLL is missing will my if work? If not, how can I detect that My.exe failed to start?
Solution

  • ERRORLEVEL will contain the return code of the last command. Sadly you can only check >= for it.

    Note specifically this line in the MSDN documentation for the If statement:

    errorlevel Number

    Specifies a true condition only if the previous program run by Cmd.exe returned an exit code equal to or greater than Number.

    So to check for 0 you need to think outside the box:

    IF ERRORLEVEL 1 GOTO errorHandling
REM no error here, errolevel == 0
:errorHandling

    Or if you want to code error handling first:

    IF NOT ERRORLEVEL 1 GOTO no_error
REM errorhandling, errorlevel >= 1
:no_error

    Further information about BAT programming: http://www.ericphelps.com/batch/ Or more specific for Windows cmd: MSDN using batch files