How exactly does EcalSys handles the processes.

[deo-abhijit]

We are trying to use Ecalsys to run binaries and Shell scripts together, while doing this we faced some hiccups. It would be really helpful if you can provide answers to some of the questions we had.

1. How does ecalsys handles shell scripts. Which shell does it use when the process starts.
2. When stop is executed by the ecalsys, which stop signal (SIGINT, SIGKILL) does it send?

In my bashscript, I've a trap for SIGKILL, and SIGINT which gracefully exits the bashscript.

This works fine when ran in the terminal, but when used from ecalsys, its not getting trapped.

my bash script somewhat looks like this,

# !/bin/bash 


python file1.py & 
pid_f1=$!


python file2.py &
pid_f2=$!

cleanup() {
    kill -9 $pid_f1;
    kill -9 $pid_f2;
    
}

trap cleanup EXIT SIGINT SIGTERM 
wait $pid_f2

This trap works well for the shell script executed from terminal, but not with ecalsys.

Please let me know if there is anything that we are missing here.

Thank you
abhijit

cc: @git-pi-e

[git-pi-e]

I also want to ask further whether there is any other way of cleanup available, using eCAL Sys itself.

TIA

[FlorianReimold]

How does ecalsys handles shell scripts. Which shell does it use when the process starts.

eCAL Sys unfortunately cannot handle shell scripts by itself. It cannot decide which interpreter to start. What you can do however is create a shell script as file and pass it to an interpreter of your choice as argument:

bash /path/to/scriptname

In eCAL Sys, this would translate to:

• Executable: bash
• Arguments: /path/to/scriptname

Note, that eCAL Sys will then only monitor the bash process and will be unaware of any other application that may be started from that script.

When stop is executed by the ecalsys, which stop signal (SIGINT, SIGKILL) does it send?

eCAL Sys will at first send an eCAL Stop signal to the processes (if they are eCAL Processes). This will cause eCAL::OK() to return false and thus enable to Application to perform a graceful shutdown. After 3 Seconds, eCAL Sys will send a SIGINT to the process. It can only send the SIGINT to the process that it started and knows the PID of, so e.g. if you pass arguments to some graphical terminal emulator, this may fail. For instance, the gnome-terminal-emulator probably executes the script in another main process and not the process that eCAL sys started and knows the PID of. I don't know if that is your issue, but it may be worth checking. eCAL Sys shows the PID of the process that it executed, so maybe check if that process continued to run or if it passed arguments to some other process and shut down already.

I also want to ask further whether there is any other way of cleanup available, using eCAL Sys itself.

I do not fully understand what you mean by cleanup and when this cleanup is supposed to happen.

• eCAL Sys stops / kills your processes, when you click the Stop button.
• There is an option available unter Options/Kill all on close that makes eCAL Sys stop all of your applications when you close eCAL Sys.
• When you closed eCAL Sys with your processes still running in the background, eCAL Sys can try to collect your applications again and re-populate the Task list. For that you need to load the same eCAL Sys file againg and click the "Update from cloud" button (the right-most button). You can then stop them again with the stop button. This feature only works for eCAL Tasks, i.e. probably not for your shell scripts.

[deo-abhijit]

@FlorianReimold thanks for the reply.

eCAL Sys unfortunately cannot handle shell scripts by itself. It cannot decide which interpreter to start. What you can do however is create a shell script as file and pass it to an interpreter of your choice as argument:
In eCAL Sys, this would translate to:
Executable: bash
Arguments: /path/to/scriptname

I think this was the missing point in our case.

If you see the generic shell script that i had shared, the script spawns two python processes in the background, and a cleanup function was written to kill the python processes when script receives EXIT signals. When i used the script as an executable in ecalsys, this cleanup was not getting triggered.

However, i changed the executable and arguments like you mentioned and the cleanup function is working.

Again,
Thanks for the detailed reply. It was really helpful.