Batch file and DEL errorlevel 0 issue

问题:

The batch has to remove files and directories from specific locations and output success or stdout/stderr messages to a new .txt file. I have created the most of the script and it performs exactly as it should, except when the deletion is successful it moves forward to the next line rather than echo a 'successful' message on the log.

echo Basic Deletion Batch Script > results.txt
@echo off
call :filelog >> results.txt 2>&1
notepad results.txt
exit /b

:filelog

call :delete new.txt
call :delete newer.txt
call :delete newest.txt
call :remove c:\NoSuchDirectory

GOTO :EOF

:delete
echo deleting %1
del /f /q c:\Users\newuser\Desktop\%1 
if errorlevel 0 echo succesful

GOTO :EOF

:remove
echo deleting directory %1
rmdir /q /s %1

GOTO :EOF

For some reason I can't find the syntax for if del succeeds echo 'successful'. In the above example if I remove the line

if errorlevel 0 echo successful

Everything works fine, but no success message. With this line left in it echoes success for every line.

回答1:

del and ErrorLevel?

The del command does not set the ErrorLevel as long as the given arguments are valid, it even resets the ErrorLevel to 0 in such cases (at least for Windows 7).

del modifies the ErrorLevel only in case an invalid switch is provided (del /X sets ErrorLevel to 1), no arguments are specified at all (del sets ErrorLevel to 1 too), or an incorrect file path is given (del : sets ErrorLevel to 123), at least for Windows 7.

Possible Work-Around

A possible work-around is to capture the STDERR output of del, because in case of deletion errors, the related messages (Could Not Find [...], Access is denied., The process cannot access the file because it is being used by another process.) are written there. Such might look like:

for /F "tokens=*" %%# in ('del /F /Q "\path\to\the\file_s.txt" 2^>^&1 1^> nul') do (2> nul set =)

To use the code in command prompt directly rather than in a batch file, write %# instead of %%#.

If you do not want to delete read-only files, remove /F from the del command line;
if you do want prompts (in case wildcards ? and/or * are present in the file path), remove /Q.

Explanation of Code

This executes the command line del /F /Q "\path\to\the\file_s.txt". By the part 2>&1 1> nul, the command output at STDOUT will be dismissed, and its STDERR output will be redirected so that for /F receives it.

If the deletion was successful, del does not generate a STDERR output, hence the for /F loop does not iterate, because there is nothing to parse. Notice that ErrorLevel will not be reset in that case, its value remains unchanged.

If for /F recieves any STDERR output from the del command line, the command in the loop body is executed, which is set =; this is an invalid syntax, therefore set sets the ErrorLevel to 1. The 2> nul portion avoids the message The syntax of the command is incorrect. to be displayed.

To set the ErrorLevel explicitly you could also use cmd /C exit /B 1. Perhaps this line is more legible. For sure it is more flexible because you can state any (signed 32-bit) number, including 0 to clear it (omitting the number clears it as well). It might be a bit worse in terms of performance though.

Application Example

The following batch file demonstrates how the above described work-around could be applied:

:DELETE
echo Deleting "%~1"...
rem this line resets ErrorLevel initially:
cmd /C exit /B
rem this line constitutes the work-around:
for /F "tokens=*" %%# in ('del /F /Q "C:\Users\newuser\Desktop\%~1" 2^>^&1 1^> nul') do (2> nul set =)
rem this is the corrected ErrorLevel query:
if not ErrorLevel 1 echo Deleted "%~1" succesfully.
goto :EOF

Presetting ErrorLevel

Besides the above mentioned command cmd /C exit /B, you can also use > nul ver to reset the ErrorLevel. This can be combined with the for /F loop work-around like this:

> nul ver & for /F "tokens=*" %%# in ('del /F /Q "\path\to\the\file_s.txt" 2^>^&1 1^> nul') do (2> nul set =)

Alternative Method Without for /F

Instead of using for /F to capture the STDERR output of del, the find command could also be used like find /V "", which returns an ErrorLevel of 1 if an empty string comes in and 1 otherwise:

del "\path\to\the\file_s.ext" 2>&1 1> nul | find /V "" 1> nul 2>&1

However, this would return an ErrorLevel of 1 in case the deletion has been successful and 0 if not. To reverse that behaviour, an if/else clause could be appended like this:

del "\path\to\the\file_s.ext" 2>&1 1> nul | find /V "" 1> nul 2>&1 & if ErrorLevel 1 (1> nul ver) else (2> nul set =)

回答2:

When using this syntax, instead of this

if errorlevel 0 echo successful

you can use this - because errorlevel 0 is always true.

if not errorlevel 1 echo successful

回答3:

As far I remember the correct syntax is:

if %errorlevel% == 0 echo succesful

That percent signs are a hint to check environment variables.

回答4:

_{This was added as an edit by the original asker, I have converted it to a community wiki answer because it should be an answer, not an edit.}

I found out how to do it... one way anyway.

echo Startup > results.txt
@echo off
call :filelog >> results.txt 2>&1
notepad results.txt
exit /b

:filelog

call :delete new.txt
call :delete newer.txt
call :delete newest.txt
call :remove c:\NoSuchDirectory

GOTO :EOF

:delete
echo deleting %1
dir c:\users\newuser\Desktop\%1  >NUL 2>&1
SET existed=%ERRORLEVEL%
del /f /q c:\Users\newuser\Desktop\%1 
dir c:\users\newuser\Desktop\%1 2>NUL >NUL
if %existed% == 0 (if %ERRORLEVEL% == 1  echo "successful" )

GOTO :EOF

:remove
echo deleting directory %1
rmdir /q /s %1

GOTO :EOF

回答5:

IF ERRORLEVEL 0 [cmd] will execute every time because IF ERRORLEVEL # checks to see if the value of ERRORLEVEL is greater than or equal to #. Therefore, every error code will cause execution of [cmd].

A great reference for this is: http://www.robvanderwoude.com/errorlevel.php

>IF /?
Performs conditional processing in batch programs.

IF [NOT] ERRORLEVEL number command
IF [NOT] string1==string2 command
IF [NOT] EXIST filename command

  NOT               Specifies that Windows should carry out
                    the command only if the condition is false.

  ERRORLEVEL number Specifies a true condition if the last program run
                    returned an exit code equal to or greater than the number
                    specified.

I would recommend modifying your code to something like the following:

:delete
echo deleting %1
del /f /q c:\Users\newuser\Desktop\%1 
if errorlevel 1 (
    rem This block executes if ERRORLEVEL is a non-zero
    echo failed
) else (
    echo succesful
)

GOTO :EOF

If you need something that processes more than one ERRORLEVEL, you could do something like this:

:delete
echo deleting %1
del /f /q c:\Users\newuser\Desktop\%1 
if errorlevel 3 echo Cannot find path& GOTO :delete_errorcheck_done
if errorlevel 2 echo Cannot find file& GOTO :delete_errorcheck_done
if errorlevel 1 echo Unknown error& GOTO :delete_errorcheck_done
echo succesful
:delete_errorcheck_done

GOTO :EOF

OR

:delete
echo deleting %1
del /f /q c:\Users\newuser\Desktop\%1 
goto :delete_error%ERRORLEVEL% || goto :delete_errorOTHER

:delete_errorOTHER
echo Unknown error: %ERRORLEVEL%
GOTO :delete_errorcheck_done
:delete_error3
echo Cannot find path
GOTO :delete_errorcheck_done
:delete_error2
echo Cannot find file
GOTO :delete_errorcheck_done
:delete_error0
echo succesful
:delete_errorcheck_done

GOTO :EOF

回答6:

The answer of aschipfl is great (thanks, helped me a lot!) using the code under Presetting ErrorLevel you get a nice standard function:

Take care to use %~1 instead of %1 in the del statement, or you will get errors if you use a quoted filename.

::######################################################################
::call :DELETE "file.txt"
::call :DELETE "file.txt" "error message"
:DELETE
  >nul ver && for /F "tokens=*" %%# in ('del /F /Q "%~1" 2^>^&1 1^> nul') do (2>nul set =) || (
    if NOT .%2==. echo %~2
  )
goto :EOF

BTW 1: You can give a nifty error message as a second parameter
BTW 2: Using :: instead of REM for comments makes the code even more readable.

回答7:

Just use 'rm' command from the UnxUtils (or gow) tools for windows. It sets the errorlevel correctly in case of any errors deleting the file.