Error Handling In Dos
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Dos Batch File Error Handling
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helping each other. Join them; it only takes a minute: Sign up Batch Files - Error Handling up vote 34 down vote favorite 2 I'm currently writing my first batch file for deploying an asp.net solution. I've been manual handling dos and donts Googling a bit for a general error handling approach and can't find anything really useful. Basically if any thing goes wrong I want to stop and print out what went wrong. Can anyone give me any pointers? batch-file share|improve this question edited Apr 29 '14 at 11:28 John Saunders 138k20175321 asked Jul 22 '09 at 9:15 bplus 2,87494574 add a comment| 5 Answers 5 active oldest votes up vote 34 down vote I generally find the conditional dos error 5 command concatenation operators much more convenient than ERRORLEVEL. yourCommand && ( echo yourCommand was successful ) || ( echo yourCommand failed ) There is one complication you should be aware of. The error branch will fire if the last command in the success branch raises an error. yourCommand && ( someCommandThatMayFail ) || ( echo This will fire if yourCommand or someCommandThatMayFail raises an error ) The fix is to insert a harmless command that is guaranteed to succeed at the end of the success branch. I like to use (call ), which does nothing except set the ERRORLEVEL to 0. There is a corollary (call) that does nothing except set the ERRORLEVEL to 1. yourCommand && ( someCommandThatMayFail (call ) ) || ( echo This can only fire if yourCommand raises an error ) See Foolproof way to check for nonzero (error) return code in windows batch file for examples of the intricacies needed when using ERRORLEVEL to detect errors. share|improve this answer edited Apr 29 '14 at 11:24 answered Jun 13 '13 at 11:27 dbenham 78k11114180 Would u mind to provide a simple example with copy or del commands, pls? –Dimi Dec 17 '13 at 14:00 Much nicer than keeping track of ERRORLEVEL, thanks! –kaveman Oct 24 '14 at 18:20 add a comment| up vote 6 down vote Other than ERR
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4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Batch Programming, Error Handling, and Start Command up vote 6 down vote favorite I am just starting to http://stackoverflow.com/questions/1164049/batch-files-error-handling learn how to script. I'm trying to understand how the system handles Error Levels and how they can be used in error handling. I know there is a difference between the environment variable %ERRORLEVEL% and the Error Level of the system. If I understand this correctly, then the If ERRORLEVEL 1 code would check the environment variable before it checks the error level of the previous command. So, in my program I http://stackoverflow.com/questions/6498460/batch-programming-error-handling-and-start-command am trying to interface a startup/stop script that will start/stop all scripts of a given machine (for testing I'm just using one application notepad.exe as an example). I have two wrapper scripts that will either start up or stop the applications by passing arguments to the independent script. If there is an error in the independent script, it will set the errorlevel using the EXIT /B n command. Once control is returned to the calling script, it will go to an error handling script if the exit status is non-zero. At first I was setting the %ERRORLEVEL% to zero manually and then testing for an error after a START or TASKKILL command. But then I read that clearing %ERRORLEVEL% with SET ERRORLEVEL= is a better method. My issue comes in when I try to start the app with START "" notepad.exe Whenever I test the errorlevel after this command it is always greater than or equal to 1 unless I use SET ERRORLEVEL=0 before I run the start command. I have inserted the code for the four scripts below. Any insight and advice would be greatly appreciated. appstart.bat: @echo off :: Script for application Start set ERRORLEVEL= :: **** :: Additional Batch files will be executed from within this file :: Example: :: Call A
don't make any sense. I'm sure they made perfect sense to me at the time. ;-) Wednesday, October 5, 2011 Common DOS batch file error handling mistakes I make I write http://armillz.blogspot.com/2011/10/common-dos-batch-file-error-handling.html a decent amount of batch scripts now days to automate things on windows server boxes. http://gerardnico.com/wiki/dos/errorlevel Unfortunately, I don't do it quite frequently enough to remember all the crazy syntax of DOS commands. One of these errors is error handling. These are the things I commonly need to deal with. I found this page (and site) very helpful for all DOS related stuff: http://www.robvanderwoude.com/errorlevel.php Use "IF %ERRORLEVEL% NEQ 0 SET MYERROR=1" to record whether the previous dos error command resulted in an error code. Alternately, you can check for "IF ERRORLEVEL 1 ..." if you want to look for a specific error level. Be cautious of manipulations with ERRORLEVEL. It's not really an environment variable like other variables. In particular, do NOT ever use "set ERRORLEVEL=5" or similar. It will corrupt any further use of %ERRORLEVEL% syntax by fixing it at a value. Use "CALL FOO.BAT" instead of just "FOO.BAT" when calling subscripts. Otherwise, error handling in when that script completes it will not return to the current script. Use "EXIT /B 1" to return an exit code from your script. If you use "EXIT 1" it will exit the entire command shell, including closing your current window if it's running in one. Consider using SETLOCAL and ENDLOCAL within your script to prevent temporary environment variables from carrying through to outer shells. Below is an example script. :: Sample script with some error handling SETLOCAL SET MYPARAM=%1 if "%MYPARAM%"=="" goto :USAGE CALL .\childscript.bat %MYPARAM% if %ERRORLEVEL% NEQ 0 set MYERROR=1 echo. echo Finished child script. Handling errors now... if %MYERROR%==1 GOTO :ERROR echo It worked! ENDLOCAL set SOME_EXTERNAL_VARIABLE=1 GOTO :EOF :USAGE echo Please provide a command line parameter. EXIT /B 2 :ERROR echo It didn't work, dude. EXIT /B 1 Update: I was wrong about the ERRORLEVEL syntax earlier, so I updated after some testing. Posted by Richard Mills at 10:01 AM Labels: DOS, windows No comments: Post a Comment Newer Post Older Post Home Subscribe to: Post Comments (Atom) Followers Blog Archive ► 2013 (1) ► November (1) ► 2012 (9) ► November (1) ► October (2) ► September (1) ► July (1) ► June (3) ► January (1) ▼ 2011 (17) ► December (1) ► November (1) ▼ October (4) Repairing 'svnsync: malformed file' error with sub... DOS bat
(Error Handling|Exit Code) Dos - Errorlevel (Error Handling|Exit Code) Table of Contents 1 - About 2 - Articles Related 3 - Error Level 4 - How to 4.1 - Before ending script 4.2 - check it 4.3 - (reinitialize|reset) it 1 - About exit code in DOS 2 - Articles Related Dos - Dynamic VariableDos - ExitDos - IfDos - (Batch) ScriptDOS - SETLOCAL and ENDLOCAL 3 - Error Level When errorlevel is: = 0, then No Error occurred > 0, then an error occurred 4 - How to 4.1 - Before ending script if %ERRORLEVEL% neq 0 ( exit /b %ERRORLEVEL% ) where: Dos - Exit 4.2 - check it You can test if with the if errorlevel statement: bat files use one % to define a variable (By using 2 %, you will get then an error) @echo off for %%v in (*.bat) do echo %v Running it cause this errors to occur: error.bat v was unexpected at this time When you check the value of the ERRORLEVEL, you get: echo %ERRORLEVEL% 9009 You can then check this kind of error with the if errorlevel statement: if errorlevel 9009 (echo bad variable initialization) else (echo that's all good) bad variable initialization But the default operator is not an equality but a “greater than”, then this “if” statement will also work if errorlevel 9000 (echo a bad thing occurs) else (echo that's all good) a bad thing occurs You can then use a string comparison with the %errorlevel% dynamic variable if %errorlevel% EQ 9009 (echo the error 9009 occurs) else (echo the error 9009 doesn't occurs) the error 9009 occurs 4.3 - (reinitialize|reset) it To reinitialize it to 0 after an error, you use the exit command with the B switch in a child batch script: For instance, with the following script named: resetErrorLevel.bat :: This script is there just to reset the error level exit /B 0 If you start this demo script: @echo off echo Before the error, the errorlevel value is: %ERRORLEVEL% copy badfile badlocation echo After the error, the errorlevel value is: %ERRORLEVEL% call resetErrorLevel.bat echo After the resetErrorLevel.bat, the errorlevel value is %ERRORLEVEL% you will get this output: Before the error, the errorlevel value is: 0 The system cannot find the file specified. After the error, the errorlevel value is: 1 After the resetErrorLevel.bat, the errorlevel value is 0 dos/errorlevel.txt · Last modified: 2015/04/24 14:43 by gerardnico Dos (Win32 Shell Scripting) and Utilities 69 pagesCommand line ArgumentAttrib Command (File Attributes)Cal