Cmd ошибка при выходе

Wow! that is freaky!

I am able to reproduce the apparent bug from the command line console by running the following (note I use /Q to turn ECHO OFF so output is simpler):

D:\test>cmd /q /c bug.cmd
before
first if

D:\test>echo %errorlevel%
0

I get the same behavior if I rename the script to «bug.bat»

I also get the expected return code of 1 if I remove the 2nd IF.

I agree, this seems to be a bug. Logically, I see no reason for the two similar scripts to yield different results.

I don’t have a full explanation, but I believe I understand an important component to the behavior: The batch ERRORLEVEL and the exit code do not refer to the same thing! Below is the documentation for the EXIT command. The important bit is the description of the exitCode parameter.

D:\test>exit /?
Quits the CMD.EXE program (command interpreter) or the current batch
script.

EXIT [/B] [exitCode]

  /B          specifies to exit the current batch script instead of
              CMD.EXE.  If executed from outside a batch script, it
              will quit CMD.EXE

  exitCode    specifies a numeric number.  if /B is specified, sets
              ERRORLEVEL that number.  If quitting CMD.EXE, sets the process
              exit code with that number.

I think the average person (including myself) does not typically distinguish between the two. But CMD.EXE seems to be very finicky as to when the batch ERRORLEVEL is returned as the exit code.

It is easy to show that the batch script is returning the correct ERRORLEVEL, yet the ERRORLEVEL is not being returned as the CMD exit code. I display the ERRORLEVEL twice to demonstrate that the act of displaying it is not clearing the ERRORLEVEL.

D:\test>cmd /q /v:on /c "bug.cmd&echo !errorlevel!&echo !errorlevel!"
before
first if
1
1

D:\test>echo %errorlevel%
0

As others have pointed out, using CALL does cause the ERRORLEVEL to be returned as the exit code:

D:\test>cmd /q /c "call bug.cmd"
before
first if

D:\test>echo %errorlevel%
1

But that doesn’t work if another command is executed after the CALL

D:\test>cmd /q /v:on /c "call bug.cmd&echo !errorlevel!"
before
first if
1

D:\test>echo %errorlevel%
0

Note that the above behavior is strictly a function of CMD.EXE, having nothing to do with the script, as evidenced by:

D:\test>cmd /q /v:on /c "cmd /c exit 1&echo !errorlevel!"
1

D:\test>echo %errorlevel%
0

You could explicitly EXIT with the ERRORLEVEL at the end of the command chain:

D:\test>cmd /q /v:on /c "call bug.cmd&echo !errorlevel!&exit !errorlevel!"
before
first if
1

D:\test>echo %errorlevel%
1

Here is the same thing without delayed expansion:

D:\test>cmd /q /c "call bug.cmd&call echo %errorlevel%&exit %errorlevel%"
before
first if
1

D:\test>echo %errorlevel%
1

Perhaps the simplest/safest work around is to change your batch script to EXIT 1 instead of EXIT /B 1. But that may not be practical, or desirable, depending on how others may use the script.

EDIT

I’ve reconsidered, and now think it is most likely an unfortunate design «feature» rather than a bug. The IF statements are a bit of a red herring. If a command is parsed after EXIT /B, within the same command block, then the problem manifests, even though the subsequent command never executes.

test.bat

@exit /b 1 & echo NOT EXECUTED

Here are some test runs showing that the behavior is the same:

D:\test>cmd /c test.bat

D:\test>echo %errorlevel%
0

D:\test>cmd /c call test.bat

D:\test>echo %errorlevel%
1

D:\test>cmd /v:on /c "call test.bat&echo !errorlevel!"
1

D:\test>echo %errorlevel%
0

It doesn’t matter what the 2nd command is. The following script shows the same behavior:

@exit /b 1 & rem

The rule is that if the subsequent command would execute if the EXIT /B were something that didn’t exit, then the problem manifests itself.

For example, this has the problem:

@exit /b 1 || rem

But the following works fine without any problem.

@exit /b 1 && rem

And so does this work

@if 1==1 (exit /b 1) else rem

• Overview
• Part 1 – Getting Started
• Part 2 – Variables
• Part 3 – Return Codes
• Part 4 – stdin, stdout, stderr
• Part 5 – If/Then Conditionals
• Part 6 – Loops
• Part 7 – Functions
• Part 8 – Parsing Input
• Part 9 – Logging
• Part 10 – Advanced Tricks

Today we’ll cover return codes as the right way to communicate the outcome of your script’s execution to the world. Sadly, even
skilled Windows programmers overlook the importance of return codes.

Return Code Conventions

By convention, command line execution should return zero when execution succeeds and non-zero when execution fails. Warning messages
typically don’t effect the return code. What matters is did the script work or not?

Checking Return Codes In Your Script Commands

The environmental variable %ERRORLEVEL% contains the return code of the last executed program or script. A very helpful feature is
the built-in DOS commands like ECHO, IF, and SET will preserve the existing value of %ERRORLEVEL%.

The conventional technique to check for a non-zero return code using the NEQ (Not-Equal-To) operator of the IF command:

IF %ERRORLEVEL% NEQ 0 (
  REM do something here to address the error
)

Another common technique is:

IF ERRORLEVEL 1 (
  REM do something here to address the error
)

The ERRORLEVEL 1 statement is true when the return code is any number equal to or greater than 1. However, I don’t use this technique because
programs can return negative numbers as well as positive numbers. Most programs rarely document every possible return code, so I’d rather explicity
check for non-zero with the NEQ 0 style than assuming return codes will be 1 or greater on error.

You may also want to check for specific error codes. For example, you can test that an executable program or script is in your PATH by simply
calling the program and checking for return code 9009.

SomeFile.exe
IF %ERRORLEVEL% EQU 9009 (
  ECHO error - SomeFile.exe not found in your PATH
)

It’s hard to know this stuff upfront – I generally just use trial and error to figure out the best way to check the return code of the program or
script I’m calling. Remember, this is duct tape programming. It isn’t always pretty, but, it gets the job done.

Conditional Execution Using the Return Code

There’s a super cool shorthand you can use to execute a second command based on the success or failure of a command. The first program/script must
conform to the convention of returning 0 on success and non-0 on failure for this to work.

To execute a follow-on command after sucess, we use the && operator:

SomeCommand.exe && ECHO SomeCommand.exe succeeded!

To execute a follow-on command after failure, we use the || operator:

SomeCommand.exe || ECHO SomeCommand.exe failed with return code %ERRORLEVEL%

I use this technique heavily to halt a script when any error is encountered. By default, the command processor will continue executing
when an error is raised. You have to code for halting on error.

A very simple way to halt on error is to use the EXIT command with the /B switch (to exit the current batch script context, and not the command
prompt process). We also pass a specific non-zero return code from the failed command to inform the caller of our script about the failure.

SomeCommand.exe || EXIT /B 1

A simliar technique uses the implicit GOTO label called :EOF (End-Of-File). Jumping to EOF in this way will exit your current script with
the return code of 1.

SomeCommand.exe || GOTO :EOF

Tips and Tricks for Return Codes

I recommend sticking to zero for success and return codes that are positive values for DOS batch files. The positive values are a good idea
because other callers may use the IF ERRORLEVEL 1 syntax to check your script.

I also recommend documenting your possible return codes with easy to read SET statements at the top of your script file, like this:

SET /A ERROR_HELP_SCREEN=1
SET /A ERROR_FILE_NOT_FOUND=2

Note that I break my own convention here and use uppercase variable names – I do this to denote that the variable is constant and should not
be modified elsewhere. Too bad DOS doesn’t support constant values like Unix/Linux shells.

Some Final Polish

One small piece of polish I like is using return codes that are a power of 2.

SET /A ERROR_HELP_SCREEN=1
SET /A ERROR_FILE_NOT_FOUND=2
SET /A ERROR_FILE_READ_ONLY=4
SET /A ERROR_UNKNOWN=8

This gives me the flexibility to bitwise OR multiple error numbers together if I want to record numerous problems in one error code.
This is rare for scripts intended for interactive use, but, it can be super helpful when writing scripts you support but you don’t
have access to the target systems.

@ECHO OFF
SETLOCAL ENABLEEXTENSIONS

SET /A errno=0
SET /A ERROR_HELP_SCREEN=1
SET /A ERROR_SOMECOMMAND_NOT_FOUND=2
SET /A ERROR_OTHERCOMMAND_FAILED=4

SomeCommand.exe
IF %ERRORLEVEL% NEQ 0 SET /A errno^|=%ERROR_SOMECOMMAND_NOT_FOUND%

OtherCommand.exe
IF %ERRORLEVEL% NEQ 0 (
    SET /A errno^|=%ERROR_OTHERCOMMAND_FAILED%
)

EXIT /B %errno%

If both SomeCommand.exe and OtherCommand.exe fail, the return code will be the bitwise combination of 0x1 and 0x2, or decimal 3. This return code tells
me that both errors were raised. Even better, I can repeatedly call the bitwise OR with the same error code and still interpret which errors were
raised.

<< Part 2 – Variables


Part 4 – stdin, stdout, stderr >>

Every scripting and programming language contains an error handler like Java contains try-catch for error handling. In a Batch script, there is no direct way to do this, but we can create an error handler in the Batch script using a built-in variable of the Batch script name %ERRORLEVEL%.

This article will show how we can create a Batch script to handle errors and failures. Also, we are going to some examples that make the topic easier.

Error Handling in Batch Script

When a command successfully executes, it always returns an EXIT CODE that indicates whether the command successfully executed or failed to execute. So, to create an error handling in a Batch file, we can use that EXIT CODE in our program.

You can follow below general format to create an error handler:

@Echo off
SomeCommand && (
  ECHO Message for Success
) || (
  ECHO Message for Failure or Error
)

We can also do that by checking the variable named %ERRORLEVEL%. If the variable contains a value not equal to 0, then there might be a problem or error when executing the command. To test the %ERRORLEVEL% variable, you can follow the below example codes:

@ECHO off
Some Command Here !!!
IF %ERRORLEVEL% NEQ 0 (Echo Error found when running the command &Exit /b 1)

You must note that the keyword NEQ means Not Equal. And the variable %ERRORLEVEL% will only contain a non-zero value if there is a problem or error in the code.

An Example That Contains Errors

Below, we shared an example. We will run a Batch file named Your_file.bat from a location.

We intentionally removed that file from the directory. So it’s an error command.

The code for our example will be:

@echo off
ECHO Running a Batch file
CD G:\BATCH\
CALL Your_file.bat
IF  errorlevel 1 GOTO ERROR
ECHO The file run successfully.
GOTO EOF

:ERROR
ECHO The file didn't run successfully.
CMD /k
EXIT /b 1

:EOF

Now, as the file doesn’t exist in the directory, it will show an error, and you will get the below output when you run the code shared above.

Output:

Running a Batch file
The system cannot find the path specified.
'Your_file.bat' is not recognized as an internal or external command,
operable program or batch file.
The file didn't run successfully.

An Error-Free Code Example That Runs Successfully

In the example above, we made a mistake on the code intentionally to understand how the code works. If we correct it like below:

@echo off
ECHO Running a Batch file
CALL "G:\BATCH\Yourfile.bat"
IF  errorlevel 1 GOTO ERROR
ECHO The file runs successfully.
GOTO EOF

:ERROR
ECHO The file didn't run successfully.
CMD /k
EXIT /b 1

:EOF

Then we will get an output like this:

Running a Batch file
This is from the first file
The file runs successfully.

Remember, all commands we discussed here are only for the Windows Command Prompt or CMD environment.

all DOS versions is the reverse order check.
Start checking the highest errorlevel that can be expected, then check for the one below, etcetera:
IF ERRORLEVEL 255 GOTO Label255
IF ERRORLEVEL 254 GOTO Label254
  •
  •
  •
IF ERRORLEVEL   2 GOTO Label2
IF ERRORLEVEL   1 GOTO Label1
GOTO Label0

This will result in many more lines of batch code, but at least it will work in any DOS version.
In Windows NT (Windows NT 4 … Windows 10) this may not suffice, though, because errorlevels can have negative integer values as well.

page last modified: 2022-04-01