I have experienced (random) weird corruption of environment variables from consecutive calls of multiple (3d party) batch scripts. These individual scripts call #echo off.
Is it possible to force echo on by environment variable/other means or I need to go to the every script and comment/remove the line to see what has been actually executed?
I'm quite sure that this is not possible. You can't force your system to simply ignore a command like ECHO OFF. The only way to I can think of as a workaround is to write a script which replaces all ECHO OFF commands in you bat files before execution and restoring them afterwards.
Take a look at this: https://superuser.com/questions/351661/how-do-i-force-echo-on-for-a-batch-file-without-editing-the-file
Related
I have to maintain a batch script of about 3500 lines littered with GOTO. Seems that the original "developer" hasn't heard of this famous paper and modular programming.
What the script does?
The script deals with the (silent) installation/uninstallation/reinstallation of several programs using different options. It could be split in several files that deal with each program in part. The problem is that if you're trying to take a part in another file that part will still GOTO another section that needs to be in the original script.
Refactoring?
Normally you wouldn't do a refactoring without having automated tests (so you can be sure you didn't break anything), but I don't know how to do it. There's no testing framework for that.
Partial Solution
I have come up with a partial "solution" that is some kind of adaptation of characterization tests (from Working Effectively with Legacy Code by Michael Feathers) and approval tests:
- create another script: test.py that replaces all commands (like copy or msiexec) with echo,
- redirect the output to a text file (good.txt),
- change the original batch script,
- run the test.py script again and save the output to another text file (current.txt),
- diff good.txt and current.txt -> if there are no differences then I didn't break anything, but if they are different I need to check if I broke something.
Problem with partial solution
How can I capture and replace all the commands? I could make a list of commands to replace, but there are also a lot of string concatenations to get the name and path of the program to be installed.
CMD level capture/hook?
Is there any way I can hook into the command line interpreter (CMD.exe) so I can replace on the fly all the calls to installers with echo?
Other suggestions?
Do I approach the problem in the wrong way? Can I do it better somehow? Do you have some advice I could use?
You could replace all COPY, DEL or CALL with %COPY%, %DEL% ,...
So you can use the same file for production and also for the tests.
#echo off
if not defined UNITTEST (
set "COPY=COPY"
set "DEL=DEL"
set "CALL=CALL"
)
%COPY% src dest
%DEL% somefile.txt
%CALL% installer.exe
And from your unittest.bat, you could start it via
#echo off
set "COPY=>>trace.log ECHO COPY"
set "DEL=>>trace.log ECHO DEL"
set "CALL=>>trace.log CALL ECHO "
del trace.log
set "unittest=Active"
call production.bat
fc good.txt trace.log
I'm not an expert in Batch, but I have done my fair share of it. With that said, I can offer a few tips.
Forget trying to do it all at once. Batch is very hard to debug. Echoing out to a log file helps a lot, but it will not capture everything you need if something goes wrong.
Work on breaking out the exe and msiexec calls into self-contained scripts. It is much easier to test the small script for the functionality you desire. Once you have that working, it is simple to call that script from the "Master" script.
Establish a good protocol for passing args to, and return codes from the smaller scripts. If there are common settings needed to be used for all the scripts consider using a central settings file.
GOTOs are not the devil, unless they pass control all over the place. Normally there are two good reasons that I know of to use GOTO’s.
Skip past a block of code that does not need to run.
To SET values into variables. Note there is a bug that can prevent variables from having their value set from within an 'IF' statement block. That little bug caused a big headache for me at one time.
Calls to a label might be better option at times.
Depending on how far back the legacy support is required, consider using Powershell when possible. The power and debugging capabilities of Powershell far out way the benefits of simple scripting of Batch. Which at 3500 lines simplicity has already been lost. You are already looking at Python, so maybe that could be used instead.
If you need a break point, use Pause. ECHO all the settings you need to examine right before the pause. This is as close to a break point I have found for batch.
Echo the command you intend to run to a log file and actually run it.
Write small verification scripts to be used independently or with the “Master” script to confirm you are getting the results you are expecting.
Use the right tool for the job. I like to use EditPadPro, RegexBuddy, and BeyondCompare for batch editing and comparing differences. There free tools that can be used too NotePad++ and Windiff. Making many edits in a file of that size is best handled by a good editor. IE inserting an echo at the beginning of a line that calls a cmd.exe.
Remember it is scripting not programming. While there is a lot of overlap of the two, the same exact approach to a problem may not be viable between the two.
Always make a backup copy of the scripts as a whole before mucking around. A fallback position is greatly appreciated when there is one small bug that you can’t find.
If it ain't broke... well you wouldn't be working on it if everything was working just fine.
Always test changes. And when you are done test it again. After that have someone else test it.
Just my .02. I’m sure someone else can chime in with more advanced advice. My knowledge on Batch has been acquired from the school of hard knocks, supplemented by ss64.com
I'm using cl in cmd and having to run vcvars32.bat every time I open a cmd window is really a pain in the axx. Can anyone offer a way of running it automatically?
From cmd /?:
If /D was NOT specified on the command line, then when CMD.EXE starts, it
looks for the following REG_SZ/REG_EXPAND_SZ registry variables, and if
either or both are present, they are executed first.
HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\AutoRun
and/or
HKEY_CURRENT_USER\Software\Microsoft\Command Processor\AutoRun
You therefore could add vcvars32.bat to one of those AutoRun registry values to have it executed for every cmd.exe instance (except when /D is explicitly specified, of course).
However, be forewarned that doing this could result in other weird side-effects (for example, it could cause other .bat/.cmd scripts to be run in an environment that they aren't expecting).
A workaround that works for some people is to write a batch file and call it A.BAT and make a.bat launch vcvars32.bat. Put a.bat on the path and then it's a matter of opening the cmd prompt and typing a and enter and voila, you're set!
way old, but the easiest way to do this with, say, a shortcut created on your TaskBar is to modify your shortcut (in %appdata%\microsoft\internet explorer\quick launch\user pinned\taskbar, or thereabouts) so the target is:
%windir%\system32\cmd.exe /k vcvars32.cmd
that'll do exactly what you're looking for. The /k tells it to execute the string but keep the window open (string being your batch file). You can either put vcvars32 somewhere in your path, or specify the whole path to vcvars32.
You can use the script in http://www.alteridem.net/2010/09/02/visual-studio-2010-command-prompt-here to make it so when you right-click a folder in explorer the option shows up. After downloading and extracting the zip file you can modify the .inf to point to the correct path to your particular VS version (and change the displayed name if desired). Note the comment on the page about having to rename the file if you are running 64-bit Windows.
If from inside a bat file you called another batch file but still had a few remaining operations to complete, how can you make sure that the call to first bat file will after completion or error, will return to the file that called it in the first instance?
Example:
CD:\MyFolder\MyFiles
Mybatfile.bat
Copy afile toHere
or
CD:\MyFolder\MyFiles
CALL Mybatfile.bat
COPY afile toHere
What is the difference between using CALL or START or none of them at all? Would this have any impact on whether it would return for the results of the copy command or not?
As others have said, CALL is the normal way to call another bat file within a .bat and return to the caller.
However, all batch file processing will cease (control will not return to the caller) if the CALLed batch file has a fatal syntax error, or if the CALLed script terminates with EXIT without the /B option.
You can guarantee control will return to the caller (as long as the console window remains open of course) if you execute the 2nd script via the CMD command.
cmd /c "calledFile.bat"
But this has a limitation that the environment variables set by the called batch will not be preserved upon return.
I'm not aware of a good solution to guarantee return in all cases and preserve environment changes.
If you really need to preserve variables while using CMD, then you can have the "called" script write the variable changes to a temp file, and then have the caller read the temp file and re-establish the variables.
call is necessary for .bat or .cmd files, else the control will not return to the caller.
For exe files it isn't required.
Start isn't the same as call, it creates a new cmd.exe instance, so it can run a called batch file asynchronosly
The `CALL' statement was introduced in MS-DOS 3.3
It is used to call other batch files within a batch file, without aborting the execution of the calling batch file, and using the same environment for both batch files.
So in your case the solution is to use CALL
Okay, I actually didn't even really think about the fact that if you call a batch (regardless of the 'type', i.e. '.bat', or '.cmd') that it won't return if you don't use call.
I've been using call myself though for a different reason that I am actually pretty surprised that no one else has brought up. Maybe I missed it. MAYBE I'M THE ONLY ONE IN THE WORLD WHO KNOWS!! :O
Probably not, but I'm going to drop this knowledge off here because it's super useful.
If you use call you can use binary logic operators to decide how to proceed based on the ERRORLEVEL result. In fact, I always was flabbergasted on how && and || existed in DOS and COULDN'T be used this way. Well, that's why.
The easiest way to test this is to create a return.cmd with notepad, or from the command prompt like so:
c:\> type con >return.cmd
You will now notice the cursor goes down to the next line and hangs. Enter:
#exit /B %1
And then hit ENTER, and then CTRL-Z and that file will be created. Good! You may now feel free to try the following two examples:
call return.cmd 0 && echo Huzzah! A Complete Success! (Or cover up...)
call return.cmd 123 || echo Oops! Something happened. You can check ERRORLEVEL if you want the tinest amount of additional information possible.
So what? Well, run them again with the 0 and the 123 swapped and you should see that the messages DON'T print.
Maybe this multi-line example will make more sense. I use this all the time:
call return.cmd 0 && #(
echo Batch says it completed successfully^^!
) || #(
echo Batch completed, but returned a 'falsey' value of sort.
call echo The specific value returned was: %ERRORLEVEL%
)
(Note the 'call' in the || section before the second 'echo'. I believe this is how people got around not having delayed expansion back in the day. If you DO have delayed expansion enabled (via. setlocal EnableDelayedExpansion inside a batch OR launch a command prompt with cmd /v:on then you can just do !ERRORLEVEL!.)
... This is where I have to apologize and say if you have if ERRORLEVEL trauma in your past you should stop reading. I get it. Trust me. I thought about paying someone on fiverr to remotely type this for me, but for completeness sake I'm just going to take one for the team and mention that you can also do the following to check errorlevel:
if ERRORLEVEL 123 #echo QUICK! MOTHERS, COVER YOUR CHILDREN'S EYES! FINGERS ARE BEING UNDONE! :'(
If you've never typed that before then GOOD! You will live longer without having to read up why exactly you aren't getting the results you expect. Cruel is the word you're looking for, not 'quirky'.
The important part that I really want to get across however is that if you try this and DON'T use 'call' it will ALWAYS execute the 'true' branch. Try it for yourself!
If I'm missing something, or you know a better way to do this, please let me know. I love learning stuff like this!
Additional information I mentioned:
I have known for quite some time that you can put redirects BEFORE commands like so:
>nul echo. This won't be displayed!
But I accidentally discovered the other day by being a dumdum that you can apparently also do:
echo A B>file.txt C
And was REALLY surprised to find a file.txt which consisted of "A B C". It appears yo can place them ANYWHERE, even inside the command. I've never seen anyone do this, nor mention it, but I HAVE seen people mention that you can prefix a line with them.
Maybe it's a bug exclusive to Windows 10 or something. If you have another version and wanna try it out and let me know I'd be interested in what you find out.
Stay nerdy!
I have a bat file as part of larger maintenance system that runs on a nightly basis, performs a bit of housekeeping, SVN updating etc. Part of this involves moving/deleting files, however, occasionally this fails due to another process not releasing a handle on the files/dirs to be moved. Is there any way to force the BAT file to override any existing handles and continue with the MOVE? I can only think of a look up method using ProcessExplorer/Assassin - although I'm not sure that would even work. Alternatively a "sleep" and then reattempt if it failed the first time, although that would be a matter of luck than solving the underlying problem. Any ideas/suggestions much appreciated. Thanks.
Robocopy has a move function, and can wait on error
Here are a few things that I have done in similar situations:
Before the move command, ensure that other script threads CD out of the target directory.
Use robocopy (from the Resource Kits) with options like retry /r:3 and wait /w:5.
Script the first action as COPY so the script can continue working, then later in the script do the deletion at the old/unneeded location.
As you've already mentioned, create a little retry loop using IF ERRORLEVEL commands to test the success of the MOVE command.
I have a batch file, this batch file will not start automatically, it will only run when i double click on it.
Can I run the batch file in the background when I double click on it.
Well, you can start it minimized with start, if that is enough. Really hiding it is difficult (although I can think of an option right now).
Basically you need to determine whether the batch has been started by double-clicking it. You can do this by defining a special variable and look for it:
#echo off
if not defined FOO (
set FOO=1
start /min "" %~0
exit /b
)
rem here whatever you wanted to do originally in the batch
As long as the FOO variable isn't defined (which is probably the default almost everywhere), this batch will launch itself minimized again, but with the variable defined first. Environments are passed to subprocesses, which is why this works.
you would generally need something else to run the script in that manor
i.e.
Create a shortcut, and set the “Run” field for the shortcut to “Minimized’.
Once you click or tab away from the cmd.exe window that the batch file is running it, it's "in the background" -- I'm not really sure what you want but it sounds like you might be asking how to run the batch file without displaying the cmd.exe window.
If so I can think of two ways: first, you can create a shortcut to the batch file, right click it, and in the properties there set the shortcut to run minimized (should be a drop down option next to Run).
You can also wrap invocation of the batch file in a VBScript file using Windows Script Host's shell object (calling the Run method) to run the batch file invisibly. Passing 0 as the intWindowStyle parameter will suppress display of a window or anything.
#Ghyath Serhal
I have used cmdow to do this on another program, it is an external application that can be used to modify the command prompt. To use it, you will need to either enter this code (see below) into it's own batch file, or into the command prompt, where it will run 'BatchFile.bat' with a hidden terminal window. I haven't found a way to use this in a single batch file, but I only found out about this today.
cmdow /run /hid 'BatchFile.bat'
Hope this helps.