I have a batch file in which I execute the following line to list the contents of an archive:
"\Program Files\7-Zip\7z.exe" l "\Backup Google Docs.7z"
The archive is intentionally corrupted.
cmd.exe displays this:
How can I catch this error in my code?
Any program's exit code is stored in the %ERRORLEVEL% variable in a batch script.
From the 7-zip manual:
7-Zip returns the following exit codes:
Code Meaning
0 No error
1 Warning (Non fatal error(s)). For example, one or more files were locked by some other application, so they were not compressed.
2 Fatal error
7 Command line error
8 Not enough memory for operation
255 User stopped the process
So: you can do:
"\Program Files\7-Zip\7z.exe" l "\Backup Google Docs.7z"
if errorlevel 255 goto:user_stopped_the_process
if errorlevel 8 goto:not_enough_memory
if errorlevel 7 goto:command_line_error
if errorlevel 2 goto:fatal_error
if errorlevel 1 goto:ok_warnings
Caution, if errorlevel N checks that %ERRORLEVEL% is greater or equal than N, therefore you should put them in descending order.
Check if the ERRORLEVEL is set to 1 just after the call to 7z.exe and react appropriately. The ERRORLEVEL is the exit code from the last program that was run. An exit code of 1 or more indicates an error while zero indicates success. The IF ERRORLEVEL command checks if the exit is greater than or equal to the argument so IF ERRORLEVEL checks for an error level of one or more.
Here is an example:
"\Program Files\7-Zip\7z.exe" l "\Backup Google Docs.7z" > nul
IF ERRORLEVEL 1 goto ziperror
#echo 7-Zip worked
goto :eof
:ziperror
#echo 7-Zip failed
goto :eof
Related
I have a post-build event that runs some commands for a c# project. The last command would sometimes cause the ERRORLEVEL value not equals to zero and then the build fails.
I want to append an extra line of command to always set the ERRORLEVEL value to zero. What is the most convenient way to do that?
if you use exit /b 0 you can return an errorlevel 0 from within a child batch script without also exiting the parent.
Seems to do the trick:
ver > nul
Not everything works, and it is not clear why. For example, the following do not:
echo. > nul
cls > nul
In a pre- or post-build event, if the return code of an executable is greater than zero, and the call to the executable is not the last line of the pre- or post-build event, a quick way to mute it and avoid triggering a check for a non-zero errorlevel is to follow the failing line with a line that explicitly returns zero:
cmd /c "exit /b 0"
This is essentially a generic combination of the previously-mentioned solutions that will work with more than just the last line of a pre- or post-build event.
I personally use this:
cd .
Works even in unix shell.
But, this one might be a bit faster:
type nul>nul
Because Process Monitor shows QueryDirectory calls on cd .
PS:
cd . has another nice side effect in the unix shell. It does restore recreated working directory in the terminal if it has been opened before the erase.
Update:
And that is a bit more faster:
call;
Any windows command to find if a file is in use or not ? :https://www.dostips.com/forum/viewtopic.php?t=5542
I found that "exit 0" looks like a good way to deal with this problem.
Usage Example:
NET STOP UnderDevService /Y
exit 0
if the UnderDevService service is not started.
I use VERIFY or VERIFY > nul
If this is a snippet like "Post-build Event" etc., then you'll be fine appending:
(...) || ver > nul
at the end of the last command.
Alternatively
cmd /c "exit /b 0"
is very clean and non-idiomatic -- a reader who knows Windows shell will know what's going on, and what was your intent.
However, if you're in a batch script, you may want to use subrotines, which are a lightweight equivalent of the "child batch script" from akf's answer.
Have a subroutine:
:reset_error
exit /b 0
and then just
call :reset_error
wherever you need it.
Here's a complete example:
#echo off
rem *** main ***
call :raise_error
echo After :raise_error ERRORLEVEL = %ERRORLEVEL%
call :empty
echo After :empty ERRORLEVEL = %ERRORLEVEL%
call :reset_error
echo After :reset_error ERRORLEVEL = %ERRORLEVEL%
:: this is needed at the end of the main body of the script
goto:eof
rem *** subroutines ***
:empty
goto:eof
:raise_error
exit /b 1
:reset_error
exit /b 0
Which outputs:
After :raise_error ERRORLEVEL = 1
After :empty ERRORLEVEL = 1
After :reset_error ERRORLEVEL = 0
As you see - just calling and returning via goto:eof is not enough.
The following works in modern Windows (NT-based) systems that feature cmd.exe:
rem /* This clears `ErrorLevel`; the SPACE can actually be replaced by an
rem arbitrary sequence of SPACE, TAB, `,`, `;`, `=`, NBSP, VTAB, FF: */
(call )
The SPACE (or more precisely, an arbitrary sequence of one or more standard token separators, which are SPACE (code 0x20), TAB (code 0x09), ,, ;, =, NBSP (code 0xFF), VTAB (code 0x0B) and FF (code 0x0C)) is mandatory; if you omit it the ErrorLevel becomes set instead:
rem // This sets `ErrorLevel` to `1`:
(call)
There is a nice thread on DosTips.com where this technique came up.
Here is an alternative method, but which accesses the file system and might therefore be a bit slower:
dir > nul
rem /* Perhaps this is a little faster as a specific file is given rather
rem than just the current directory (`.` implicitly) like above: */
dir /B "%ComSpec%" > nul
Here are some other ways to reset the ErrorLevel state, which even work in MS-DOS (at least for version 6.22):
more < nul > nul
rem // The `> nul` part can be omitted in Windows but is needed in MS-DOS to avoid a line-break to be returned:
sort < nul > nul
The following methods work in MS-DOS only:
command /? > nul
fc nul nul > nul
keyb > nul
For the sake of completeness, this sets the ErrorLevel state to 1, valid for both Windows and MS-DOS:
< nul find ""
After reviewing all of the other answers, I decided to find which way was the most efficient for resetting the ERRORLEVEL. I made a quick script that recorded the time to execute each of these:
"cmd /c "exit /b 0"", "cd .", "ver", "type nul", and "VERIFY"
here is the output:
cmd /v:on /c set ^"q=^"^" & timeit.cmd "cmd /c ^!q^!exit /b 0^!q^!" "cd ." "ver" "type nul" "VERIFY"
cmd /c "exit /b 0" took 0:0:0.02 (0.02s total)
cd . took 0:0:0.00 (0.00s total)
Microsoft Windows [Version 10.0.18362.836]
ver took 0:0:0.00 (0.00s total)
type nul took 0:0:0.00 (0.00s total)
VERIFY is off.
VERIFY took 0:0:0.00 (0.00s total)
This took 0:0:0.06 (0.06s total)
after reviewing with Measure-Command {command} in Powershell, I found that it only really accepted cd . and cmd /c "exit /b 0" --am I doing something wrong?
I'd recommend either cd . or type nul since neither have a footprint on the output of the console, nor are they slow in any measure.
yeah I'm pretty bored
Add >nul after each command that's likely to fail - this seems to prevent the build from failing.
You can still check the result of the command by examining %errorlevel%.
For example:
findstr "foo" c:\temp.txt>nul & if %errorlevel% EQU 0 (echo found it) else (echo didn't find it)
I'm using this:
ping localhost -n 1 >null
I always just used;
set ERRORLEVEL=0
I've been using it for donkey's years.
I am trying to write the below code, and I want it to display the error before it exits, but whenever I run it, it exits right away.
#echo off
cd "haha"
if %errorlevel% 1 (
echo Failure reason given is %errorlevel%
sleep 5
exit /b %errorlevel%
)
echo files deleted successfully!
del /Q *
pause
I have also tried timeout /t 5 doesn't seem to work.
This should work :
#echo off
cd "haha" 2>nul
if %errorlevel%==1 (
echo Failure reason given is %errorlevel%
timeout /t 5
exit /b %errorlevel%
)
The correct syntax is
if errorlevel 1 (
meaning if errorlevel is 1 or greater
OR
if %errorlevel% geq 1 (
which means the same thing.
As it stands, cmd is interpreting you code as
if 1 1 (
(assuming errorlevel is 1). This is a syntax error, so cmd shows a message. If you are running by point-click and giggle, the window will close. If you are running from the prompt, then cmd will report a syntax error.
Be warned however that executing an exit statement from the prompt will abort the cmd instance. Better to use goto :eof unless you have good reason otherwise.
timeout /t 5 should work, but will generate a countdown.
timeout /t 5 >nul should appear simply to wait. The issue is that you have to solve the if syntax first, else the timeout instruction won't be reached.
I'm newbie in using batch on Windows and have a question about the use of errorlevel.
I referenced TechNet(Exit) and many examples on google.
Most of them used /b with %errorlevel% like this
if errorlevel 1 exit /b %errorlevel%
I wonder the difference between
if errorlevel 1 exit /b
and
if errorlevel 1 exit /b %errorlevel%
I think there are no difference because %errorlevel% is not changed. Am I wrong?
TL;DR
Most of the time there should be no difference, but technically exit /b %errorlevel% is strictly worse than exit /b if what you want is to exit without changing the error level.
Analysis
EXIT /B without the optional errorlevel parameter does not change the error level, so as a standalone command it is exactly equivalent to EXIT /B %errorlevel% provided that %errorlevel% resolves to the current error level.
But there are cases where it might not do so:
If an environment variable named ERRORLEVEL is defined then %errorlevel% always resolves to its value (which can be arbitrary), and not to the current error level.
If command extensions are disabled then %errorlevel% will never resolve to the current error level (it will still read the value of the environment variable with that name, if defined). You can verify this by starting a command prompt with CMD /E:OFF and trying ECHO %errorlevel%.
The current error level value as produced by %errorlevel% will be fixed at the time the command is parsed, not at the time execution reaches that expression. This can result in the wrong value being produced for more complex commands. Example:
copy j:\not_existing q:\not_existing & echo %errorlevel%
This will not produce the same result as
copy j:\not_existing q:\not_existing
echo %errorlevel%
because in the first case %errorlevel% will not produce the updated error level caused by the failed copy.
For example, in a batch file, I typed the command below:
xcopy C:\fileA.txt D:\Dir\ /y /d
It will fail absolutely if there was not a file called fileA.txt. But I want to know if it fails, then output some messages to user. How can I do this?
Any help will be grateful, thanks!
Most commands/programs return a 0 on success and some other value, called errorlevel, to signal an error.
You can check for this in you batch for example by
if not errorlevel 0 goto ERR
xcopy errorlevels:
0 - All files were copied without errors
1 - No files were found to copy (invalid source)
2 - XCOPY was terminated by Ctrl-C before copying was complete
4 - An initialization error occurred.
5 - A disk-write error occurred.
[1] http://m.computing.net/answers/dos/xcopy-errorlevels/7510.html
I think what you are interested in is "error levels". See http://www.robvanderwoude.com/errorlevel.php. Basically, in your batch file, you can check the status code of the command (similar to Unix or Linux) by saying
IF ERRORLEVEL 1 <do something>
IF ERRORLEVEL 2 <do something>
where 1 and 2 are possible values of the status code returned by the last program executed. You can also do something like
echo %ERRORLEVEL%
to print out the status code, but note that it does not always behave like a "normal" environment variable. One thing that makes it different is that it does not show up with the "set" command.
I found the accepted answer didn't work but this did:
if %ERRORLEVEL% neq 0 goto ERR
Just use the following structure:
command > nul 2> nul && (
echo Success
REM can be multi line
) || (
echo Error
REM can be multi line
)
I have a post-build event that runs some commands for a c# project. The last command would sometimes cause the ERRORLEVEL value not equals to zero and then the build fails.
I want to append an extra line of command to always set the ERRORLEVEL value to zero. What is the most convenient way to do that?
if you use exit /b 0 you can return an errorlevel 0 from within a child batch script without also exiting the parent.
Seems to do the trick:
ver > nul
Not everything works, and it is not clear why. For example, the following do not:
echo. > nul
cls > nul
In a pre- or post-build event, if the return code of an executable is greater than zero, and the call to the executable is not the last line of the pre- or post-build event, a quick way to mute it and avoid triggering a check for a non-zero errorlevel is to follow the failing line with a line that explicitly returns zero:
cmd /c "exit /b 0"
This is essentially a generic combination of the previously-mentioned solutions that will work with more than just the last line of a pre- or post-build event.
I personally use this:
cd .
Works even in unix shell.
But, this one might be a bit faster:
type nul>nul
Because Process Monitor shows QueryDirectory calls on cd .
PS:
cd . has another nice side effect in the unix shell. It does restore recreated working directory in the terminal if it has been opened before the erase.
Update:
And that is a bit more faster:
call;
Any windows command to find if a file is in use or not ? :https://www.dostips.com/forum/viewtopic.php?t=5542
I found that "exit 0" looks like a good way to deal with this problem.
Usage Example:
NET STOP UnderDevService /Y
exit 0
if the UnderDevService service is not started.
I use VERIFY or VERIFY > nul
If this is a snippet like "Post-build Event" etc., then you'll be fine appending:
(...) || ver > nul
at the end of the last command.
Alternatively
cmd /c "exit /b 0"
is very clean and non-idiomatic -- a reader who knows Windows shell will know what's going on, and what was your intent.
However, if you're in a batch script, you may want to use subrotines, which are a lightweight equivalent of the "child batch script" from akf's answer.
Have a subroutine:
:reset_error
exit /b 0
and then just
call :reset_error
wherever you need it.
Here's a complete example:
#echo off
rem *** main ***
call :raise_error
echo After :raise_error ERRORLEVEL = %ERRORLEVEL%
call :empty
echo After :empty ERRORLEVEL = %ERRORLEVEL%
call :reset_error
echo After :reset_error ERRORLEVEL = %ERRORLEVEL%
:: this is needed at the end of the main body of the script
goto:eof
rem *** subroutines ***
:empty
goto:eof
:raise_error
exit /b 1
:reset_error
exit /b 0
Which outputs:
After :raise_error ERRORLEVEL = 1
After :empty ERRORLEVEL = 1
After :reset_error ERRORLEVEL = 0
As you see - just calling and returning via goto:eof is not enough.
The following works in modern Windows (NT-based) systems that feature cmd.exe:
rem /* This clears `ErrorLevel`; the SPACE can actually be replaced by an
rem arbitrary sequence of SPACE, TAB, `,`, `;`, `=`, NBSP, VTAB, FF: */
(call )
The SPACE (or more precisely, an arbitrary sequence of one or more standard token separators, which are SPACE (code 0x20), TAB (code 0x09), ,, ;, =, NBSP (code 0xFF), VTAB (code 0x0B) and FF (code 0x0C)) is mandatory; if you omit it the ErrorLevel becomes set instead:
rem // This sets `ErrorLevel` to `1`:
(call)
There is a nice thread on DosTips.com where this technique came up.
Here is an alternative method, but which accesses the file system and might therefore be a bit slower:
dir > nul
rem /* Perhaps this is a little faster as a specific file is given rather
rem than just the current directory (`.` implicitly) like above: */
dir /B "%ComSpec%" > nul
Here are some other ways to reset the ErrorLevel state, which even work in MS-DOS (at least for version 6.22):
more < nul > nul
rem // The `> nul` part can be omitted in Windows but is needed in MS-DOS to avoid a line-break to be returned:
sort < nul > nul
The following methods work in MS-DOS only:
command /? > nul
fc nul nul > nul
keyb > nul
For the sake of completeness, this sets the ErrorLevel state to 1, valid for both Windows and MS-DOS:
< nul find ""
After reviewing all of the other answers, I decided to find which way was the most efficient for resetting the ERRORLEVEL. I made a quick script that recorded the time to execute each of these:
"cmd /c "exit /b 0"", "cd .", "ver", "type nul", and "VERIFY"
here is the output:
cmd /v:on /c set ^"q=^"^" & timeit.cmd "cmd /c ^!q^!exit /b 0^!q^!" "cd ." "ver" "type nul" "VERIFY"
cmd /c "exit /b 0" took 0:0:0.02 (0.02s total)
cd . took 0:0:0.00 (0.00s total)
Microsoft Windows [Version 10.0.18362.836]
ver took 0:0:0.00 (0.00s total)
type nul took 0:0:0.00 (0.00s total)
VERIFY is off.
VERIFY took 0:0:0.00 (0.00s total)
This took 0:0:0.06 (0.06s total)
after reviewing with Measure-Command {command} in Powershell, I found that it only really accepted cd . and cmd /c "exit /b 0" --am I doing something wrong?
I'd recommend either cd . or type nul since neither have a footprint on the output of the console, nor are they slow in any measure.
yeah I'm pretty bored
Add >nul after each command that's likely to fail - this seems to prevent the build from failing.
You can still check the result of the command by examining %errorlevel%.
For example:
findstr "foo" c:\temp.txt>nul & if %errorlevel% EQU 0 (echo found it) else (echo didn't find it)
I'm using this:
ping localhost -n 1 >null
I always just used;
set ERRORLEVEL=0
I've been using it for donkey's years.