Restart batch file on crash/error - file

Question

I have a batch file that encounters several errors. These errors require the command prompt to be forcefully closed. Which causes me to have to open the file again to fix the issue.
Due to the nature of this application it is required to run all the time.
I'm looking for a way to automate the file to restart when it encounters an error. Is there a command I can do this with?
Could you please describe in detail and why the command accomplishes such a resolution?

Answer 1

Update:
What I would recommend to accomplish your goal, would be to turn your batch into a Service. (Documentation here) By converting your batch into a Service it no longer becomes subject to users being logged in, permission issues, it will run as a SYSTEM ACCOUNT. This in itself can alleviate a lot of anger for the process.
After you've completed that, you can write a batch file that ensures that your Service is indeed running. Your current issue, is it doesn't automatically restart. Well, a Service always runs- Even if it has an error it will still attempt to run.
Which means unless it has a Fatal Exception your Service should always work- But for certainty you can create a batch that will ensure your Service is running.
An example:
:START
timeout 3600
for /F "tokens=3 delims: " %%H in ('sc query "MyServiceName" ^| findstr "
if /I "%%H" NEQ "RUNNING" (
NET START "MyServiceName"
REM Service has Started...
)
)
GOTO START
So in theory every 3,600 seconds it will test if your Service is running, if it isn't it will start the Service for you.
Important:
This is more the proper way to resolve your issue, rather then circumvent it. However, as I noted your batch should still implore Exception Handling to ensure your application doesn't fall into an unusable state. This still isn't the best way, as it should implore Exception Handling and Verification to test against it's state.
As I mentioned before, you have a lot of methods to solve your issue. However, your thinking in a Linear Mindset. Which means:
Execute Command, Goal Guaranteed.
If I do this, this happens.
Essentially based on the minimal example I saw, it looks like you've created an infinite loop to continually execute your command. My question to you: When your loop has an error, how can it continue to run?
You've already stated that it happens in random areas- Nothing is random, those are more then likely areas that require some verification / testing to ensure it remains in a proper state. The faster your identify the potential problems, the more effective your program can run with no errors.
Hopefully that helps-
What exactly does your batch application do?
The reason I ask is because you can circumvent the issue with Windows Task Scheduler which allows you to configure some parameters to auto start and auto open particular applications based on your specified criteria. Will it be ideal? Will it truly automate to your needs- More then likely not.
As mentioned above by GolezTrol, the cause of your error will be the more important aspect to resolve your issue. Based on your remark
The errors are different each time, to be honest.
That could be an indicator that the batch script doesn't adhere to testing but rather assuming it successfully completed. Without any underlining information such as:
Function
Code Example
Where an error occurred, and during what task.
It makes it relatively difficult to point you in the proper direction. One thing that I would consider is IF. This is a fundamentally basic task but is quite important-
if(Directory.Exists(dirName))
{
// Do This
}
else
{
// Do This
}
I find the C# outline an easier method to understand the purpose of the IF. You can actually implement something similar in your batch. You would accomplish it like this:
if exist { insert file name } (
rem file exists
) else (
rem file doesn't exists
)
or you can accomplish it like this:
if exists c:\myFile.bat notepad c:\myFile.bat
If C:\myFile.bat exists, then open notepad. The reason this is an important is because if the variable doesn't exists, then it can not be affected. This allows your application to essentially make decisions in a very primitive manner.
You have quite a bit of flexibility- There are a lot of examples on this topic because batch programming has been around for a very, very long time. Another alternative would be to eventually move to Powershell. It will have access to the Windows Management Interface (WMI).
Hopefully this points you in the right direction, without more information our answers may not be much help.

Answer 2

I believe, that easiest way is to create one more .bat file with GOTO statement:
#echo off
:startover
echo (%time%) App started.
call "c:\app.bat"
echo (%time%) WARNING: App closed or crashed, restarting.
goto startover

Answer 3

Possibly this will fix your problem:
http://nssm.cc/usage
Basically what it does is you adding some bat file to nssm and making it a service.
In "Action on exit" part it says:
To configure the action which nssm should take when the application exits, edit the default value of the key HKLM\System\CurrentControlSet\Services\servicename\Parameters\AppExit. If the key does not exist in the registry when nssm runs it will create it and set the value to Restart.