Waiting for closing of previously started program - windows

I would like to ask you how to specify waiting for closing of specific program which was started before. I am showing here an example with command waitfor but unfortunately I don't know how to write it correctly, therefore I am asking you for help.
system('"C:\Program Files\Google\Chrome\Application\chrome.exe" &');
waitfor "closing of chrome.exe"

You should follow the advice in this other Q&A to find the PID of the new program right after you start it. Then, in a loop, check to see if that PID is still running (using again the same process as before), and pause(1) to avoid checking too frequently.

I guess you can do something like:
time_in_seconds=60
while ~isfile("output_folder/file.db")
pause(time_in_seconds)
end
Note that this program, as is, requires that file to exist at some point, otherwise infinite loop. Make sure you put safeguards to end it in case the file does not get created (like a time limit).
But I am not sure it makes sense to have MATLAB waiting for 40 minutes for a script to finish...

Related

With Scilab execution paused, how can I find out which point it is at?

When I put a "pause" command into my program, I can precede it with a disp("Just finished averaging") or something of the kind, so I can read on the console which "pause" I am at.
But when I lose my patience with a program that's taking forever to complete, and hit Ctrl-C to see what is going on, I cannot see a way of finding out which code line I interrupted it at. The "whereami" command tells me I am in pause, which is obviously true but hardly helpful; it's like a GPS device telling me I'm in the driver seat. Oh yeah, I figured that myself, thank you Captain.
I am tempted to create a dedicated variable, say MyApproximateCurrentCodeLine, and updating it every few lines of code with hard-wired substitution commands. This would work but would take a lot of time to write, a similar amount of time to remove when I'm done, and would have to be repeated with every program I need to debug. Not to mention it's just plain ugly.
Is there a better way of finding the current execution point?
Once you have interrupted the program
[linenum, callername] = where()
will give you the full calling tree.
S.

run sofware for a fixed time

I am creating a batch file which is calling other batch file. Sometimes the second batch file gives an error (because the license for the software I am running is not found). When the error hits, a window pop ups and I need to close manually (undesirable because it needs to run in a loop).
I would like to call the second batch file and if it didn't finish to run after 90seconds, kill it and go to the next line of my first batch file.
Is that possible?
Pause, sleep, timeout, and a few others can help you.
I would suggest timeout.
timeout /t 90
Here's some more info: http://www.wikihow.com/Delay-a-Batch-File
To do exactly what you want you'll have to work in some logic to decide what to do after the timeout, but you will likely use a loop after that. It depends on the structure of your code. Maybe toggle a boolean variable to determine if you want to go to the top of the script.

How can I handle a `system` call which fails?

I have a Perl script which calls an external program. (Right now I'm actually using backticks, but I could just as easily use system or something from cpan.) Sometimes the program fails, causing Windows to create a dialog box "(external program) has stopped working" with the text
Windows is checking for a solution to the problem...
shortly replaced with
A problem caused the program to stop working correctly. windows will close the program and notify you if a solution is available.
Unfortunately, this error message stops the process from dying, causing Perl to not return until the user (me!) clicks "Cancel" or "Close Program". Is there a way to avoid this behavior?
In my use case it is acceptable to have the program fail -- it does useful but strictly not necessary work. But as it needs to run unattended I can't have it block the program's remaining work.
The problem with your current approach is that backticks & system block while the external program is running/hanging. Possible other aproaches might include.
Using threads & various modules from the Win32 family to busy-wait for the process end or click on the dialong box. This is probably overkill.
Use an Alarm Signal or Event to wake up your program when the external program has taken 'too long' to respond.
Use an IPC Module to open the program and monitor it's progress.
If you don't need the child program's return value, STDOUT or STDERR, simbabque's exec option has merit, but if you need to keep a handle on the process, try Win32::Process. I've found this useful on many an occasion. The module's wait method can be an excellent alternative to my Alarm suggestion or simabque's sleep suggestion with the added benefit that your program will not sleep longer than required by the child.
If you do not need to wait for the external program to finish running to continue, you can do exec instead of system and it will never return.
You could always add a sleep $n afterwards to make it wait for the external program to theoretically finish.
exec('maybe_dies.exe');
sleep 1; # make sure it does stuff before it dies, or not, or whatever...

How to execute and manage ruby script from ruby?

I have a script named program.rb and would like to write a script named main.rb that would do the following:
system("ruby", "program.rb")
constantly check if program.rb is running until it is done
if program.rb has reached completion
exit main.rb
end
otherwise keep doing this until program.rb reaches completion{
if program.rb is not running and stopped before completing
restart program.rb from where it left off
end}
I've looked into Pidify but could not find a way to apply it to fit this exactly the right way...
Any help in how to approach this script would be greatly appreciated!
Update:
I could figure out how to resume running the script from where it left off in program.rb if there's no way to do it in main.rb
It's impossible to "restart script from where it left off" without full cooperation from the program.rb. That is, it should be able to advertise its progress (by writing current state to a file, maybe?) and be able to start correctly from a step specified in ARGV. There's no external ruby magic that can replace this functionality.
Also, if a program terminated abnormally, it means one of two things:
the error is (semi-)permanent (disk is full, no appropriate access rights to a file, etc). In this case, simply restarting the program would cause it to fail again. And again. Infinite fail loop.
the error is temporary (shaky internet connection). In this case, program should do better job with exception handling and retry on its own (instead of terminating).
In either case, there's no need for restarting, IMHO.
Well, here is one way.
Modify program.rb to take an optional flag argument --restart or something.
When program.rb starts up without this argument it will initialize a file to record its current state. Periodically, it will write whatever it needs into this file to record some kind of checkpoint.
When program.rb starts up with the restart flag, it will read its checkpoint file and start processing at that point. For this to work, it must either checkpoint all state changes or arrange for all processing between checkpoints to be idempotent so it can be repeated without ill effect.
There are lots of ways to monitor the health of program.rb. The best way is with some sort of ping, perhaps something like GET /health_check or a dummy message via a socket or pipe. You could just have a locked file to detect if the lock is still held, or you could record the PID on startup and check that it still exists.

Getting previous exit code of an application on Windows

Is there any way to find out what was the last Exit Code of an application the last time it run?
I want to check if application wasn't exit with zero exit code last time (which means abnormal termination in my case) And if so, do some checking and maybe fix/clean up previously generated data.
Since some applications do this (they give a warning and ask if you want to run in Safe Mode this time) I think maybe Windows can tell me this.
And if not, what is the best practice of doing this? Setting a flag on a file or something when application terminated correctly and check that next time it executed?
No, there's no permanent record of the exit code. It exists only as long as a handle to the process is kept open. And returned by GetExitCodeProcess(), it needs that handle. As soon as the last handle is closed then that exit code is gone for good. One technique is a little bootstrapper app that starts the process and keeps the handle. It can then also do other handy things like send alerts, keep a log, clean up partial files or record minidumps of crashes. Use WaitForSingleObject() to detect the process exit.
Btw, you definitely want to exit code number to mean the opposite thing. A zero is always the "normal exit" value. This helps you detect hard crashes. The exit code is always non-zero when Windows terminates the app forcibly, set to the exception code.
There are other ways, you can indeed create a file or registry key that indicates the process is running and check for that when it starts back up. The only real complication with it is that you need to do something meaningful when the user starts the program twice. Which is a hard problem to solve, such apps are usually single-instance apps. You use a named mutex to detect that an instance of the program is already running. Imprinting the evidence with the process ID and start time is workable.
There is no standard way to do this on the Windows Platform.
The easiest way to handle this case is to put a value on the registry and to clear it when the program exits.
If the value is still present when the program starts, then it terminated unexpectedly.
Put a value in the HKCU/Software// to be sure you have sufficient rights (the value will be per user in this case).

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