This lack of consistency in the ERRORLEVELs raised makes debugging a. BAT script and the first command fails but the second succeeds, the ERRORLEVEL may or may not remain set depending on which command was run. Other internal and external commands do not follow this rule. BAT batch script running the internal commands: APPEND, ASSOC, PATH, PROMPT, FTYPE and SET will only change the ERRORLEVEL if an error occurs. CMD batch script will set/reset the ERRORLEVEL after every command that you run Mark Zbikowski (MSFT).Ī. There is a key difference between the way. cmd Batch scripts.Īlthough the differences are minor, there are no advantages to the.
#Error code
In most cases the ERRORLEVEL will be the same as the Exit code, but there are some cases where they can differ.Īn Exit Code can be detected directly with redirection operators (Success/Failure ignoring the ERRORLEVEL) this can often be more reliable than trusting the ERRORLEVEL which may or may not have been set correctly. When an external command is run by CMD.EXE, it will detect the executable's Return or Exit Code and set the ERRORLEVEL to match. Some utilities behave differently depending on the severity of the error.Įrror messages are likely to be different for each language/ locale so it is generally more robust to just test the ERRORLEVEL rather than any text message output. Many utilities set an ERRORLEVEL and also output some error text, some utilities set an ERRORLEVEL but don't display error text and some will display error text without setting an ERRORLEVEL. In addition to setting an ERRORLEVEL, many utilities will output an error message on the error stream (STDERR), by default these messages will appear on the console, but they can be redirected with 2>. Raymond Chen explains: ERRORLEVEL is not the same as the %ERRORLEVEL% environment variable. When ending a subroutine, you can use EXIT /b N to set a specific ERRORLEVEL N. This allows you to trap errors that can be negative numbers, you can also test for specific errors: IF %ERRORLEVEL% EQU 0 Echo No error found || Echo An error was found IF %ERRORLEVEL% EQU 0 (Echo No error found) ELSE (Echo An error was found) IF %ERRORLEVEL% EQU 0 Echo No error found IF %ERRORLEVEL% NEQ 0 Echo An error was found
This is not very readable or user friendly and does not account for negative error numbers.Ī preferred method of checking Errorlevels is to use the %ERRORLEVEL% variable: IF ERRORLEVEL N IF NOT ERRORLEVEL N+1 COMMAND To check for a specific error level N, you can use the following construct: IF NOT ERRORLEVEL 3 means if ERRORLEVEL is less than 3 ( 2, 1, 0 or a negative number). IF ERRORLEVEL 1 will return TRUE whether the errorlevel is 1 or 5 or 64 IF ERRORLEVEL 0 will return TRUE whether the errorlevel is 0, 1 or 5 or 64 IF ERRORLEVEL n statements should be read as IF Errorlevel >= number The errorlevel is made available via IF ERRORLEVEL. There are two different methods of checking an errorlevel, the first syntax provides compatibility with old. If you attempt to execute a non-existent command %ERRORLEVEL% will be set to 9009 Detecting Errorlevels Some utilities will return negative numbers as an exit code. The exit codes set by resource kit utilities are not always consistent, they can vary between machines with different Service packs/Resource kit updates applied. The exit codes that are set do vary, in general a code of 0 (false) will indicate successful completion.īy default SCCM will only consider 0 a success, but commands like Robocopy may return success Exit Codes from 0 to 7. Almost all applications and utilities will set an Exit Code when they complete/terminate.
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