Set errorlevel in Windows batch file

@ECHO OFF
SETLOCAL
DEL output.txt 2>nul
REM Loop through each line of input.txt
FOR /F "tokens=1-3 delims=, " %%i IN (.\ready\input.txt) DO (
  ECHO.
  ECHO.
  ECHO.
  ECHO Check %%i exists, set error flag if it doesnt
  if exist .\ready\%%i (set "errorflag=") ELSE (set errorflag=2)
CALL echo return code is %%errorflag%%

  ECHO Run %%i if it exists
  if NOT DEFINED errorflag (
   call .\ready\%%i
   ECHO Move %%i to archive if no error occured
   if errorlevel 1 (SET errorflag=3) ELSE (ECHO copy .\ready\%%i .\archive\%mydate%_%mytime%_%%j_%%k_%%i)
  )
  ECHO Copy line of text to the new output.txt file if an error occured
  if DEFINED errorflag >>output.txt ECHO %%i, %%j, %%k
)
GOTO :EOF

Here's a rewritten procedure.

Note: output.txt is deleted at the start, else the >> would append to any existing file. 2>nul suppresses error messages if the delete fails (eg. file not exist)

Within a block statement (a parenthesised series of statements), the ENTIRE block is parsed and THEN executed. Any %var% within the block will be replaced by that variable's value AT THE TIME THE BLOCK IS PARSED - before the block is executed.

Hence, IF (something) else (somethingelse) will be executed using the values of %variables% at the time the IF is encountered.

Two common ways to overcome this are 1) to use setlocal enabledelayedexpansion and use !var! in place of %var% to access the chnaged value of var or 2) to call a subroutine to perform further processing using the changed values.

Note therefore the use of CALL ECHO %%var%% which displays the changed value of var. CALL ECHO %%errorlevel%% displays, but sadly then RESETS errorlevel.

IF DEFINED var is true if var is CURRENTLY defined.

ERRORLEVEL is a special varable name. It is set by the system, but if set by the user, the user-assigned value overrides the system value.

IF ERRORLEVEL n is TRUE if errorlevel is n OR GREATER THAN n. IF ERRORLEVEL 0 is therefore always true.

The syntax SET "var=value" (where value may be empty) is used to ensure that any stray spaces at the end of a line are NOT included in the value assigned.

The required commands are merely ECHOed for testing purposes. After you've verified that the commands are correct, change ECHO COPY to COPY to actually copy the files.

I used the following input.txt:

seterr1.bat, J1, K1
seterr5.bat,J2,K2
seterr0.bat,J3 K3
seterr5.bat, J4, K4
notexist.bat, J5, K5

With existing files seterr*.bat which contain

@ECHO OFF
EXIT /b 1

(where the 1 in the last line determines the errorlevel returned)

and received the resultant output:

Check seterr1.bat exists, set error flag if it doesnt
return code is 
Run seterr1.bat if it exists
Move seterr1.bat to archive if no error occured
Copy line of text to the new output.txt file if an error occured

Check seterr5.bat exists, set error flag if it doesnt
return code is 
Run seterr5.bat if it exists
Move seterr5.bat to archive if no error occured
Copy line of text to the new output.txt file if an error occured

Check seterr0.bat exists, set error flag if it doesnt
return code is 
Run seterr0.bat if it exists
Move seterr0.bat to archive if no error occured
copy .\ready\seterr0.bat .\archive\__J3_K3_seterr0.bat
Copy line of text to the new output.txt file if an error occured

Check seterr5.bat exists, set error flag if it doesnt
return code is 
Run seterr5.bat if it exists
Move seterr5.bat to archive if no error occured
Copy line of text to the new output.txt file if an error occured

Check notexist.bat exists, set error flag if it doesnt
return code is 2
Run notexist.bat if it exists
Copy line of text to the new output.txt file if an error occured

Note that the COPY is merely ECHOed as I mentioned earlier.

and output.txt

seterr1.bat, J1, K1
seterr5.bat, J2, K2
seterr5.bat, J4, K4
notexist.bat, J5, K5

ERRORLEVEL and %ERRORLEVEL% are two different variables. That means your code with echo return code is %errorlevel% and if %errorlevel% NEQ 0 >>output.txt %%i, %%j, %%k is probably wrong.

ERRORLEVEL is builtin and used to fetch the result of the last command. You can use it like:

IF ERRORLEVEL 1 ECHO error level is 1 or more

ERRORLEVEL cannot be set, just like bash does not let you set ?= ...

%ERRORLEVEL% is an environmental variable. If %ERRORLEVEL% is set, then its used in your script when you use %ERRORLEVEL%. If %ERRORLEVEL% is not set AND if command extensions are enabled, then it falls back to ERRORLEVEL. ERRORLEVEL does not update %ERRORLEVEL%.

Raymond Chen has a good blog entry on it: ERRORLEVEL is not %ERRORLEVEL%. Some of the content in this answer was shamelessly lifted from it.


Use something like the following subroutine:

:return
   ECHO @exit /b %1 >ret.cmd
   CALL ret.cmd
   GOTO :eof

Then use it like this:

:Attempt
   SETLOCAL
   CALL somethingThatFails
   SET retcode=!errorlevel!
   CALL somethingThatPasses : don't care about the errorlevel here
   CALL :return !retcode!
   ENDLOCAL
   CALL :eof

So, the whole thing would looke something like:

test.cmd...

@ECHO OFF

SETLOCAL ENABLEDELAYEDEXPANSION

CALL :Attempt
IF !errorlevel! NEQ 0 (ECHO Attempt Failed) ELSE (ECHO Attempt succeeded!)
GOTO :eof

:Attempt
   SETLOCAL
   CALL somethingThatFails
   SET retcode=!errorlevel!
   CALL somethingThatPasses : don't care about the errorlevel here
   CALL :return %retcode%
   ENDLOCAL
   CALL :eof

:return
   ECHO @exit /b %1 >return.cmd
   CALL ret.bat
   GOTO :eof

somethingthatfails.cmd...

DIR some command that fails >nul 2>&1

somethingthatpasses.cmd...

DIR >nul 2>&1

The one side effect of this is a file laying around called ret.cmd. I usually use an :end subroutine that does cleanup and would delete it.

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