Why is Python subprocess return code always 0 when running Modelsim Executable?

I am using python's subprocess to start modelsim executable. In the CLI, I enter quit -f -code<-5>. This should exit modelsim with exit code -5. I've tried multiple different subprocesses such as call/run/check_call/checkoutput but they all return 0 as if it successfully ran. If modelsim is exiting with a non-zero exit code shouldn't the subprocesses be returning non-zero return code and also raising CalledProcessError?

For example:
python example.py in CLI
status = subprocess.call([r"C:\...\...\vsim.exe", "-c", "-do"]) in python script
quit -f -code<non-zero integer> in CLI

Solution

Instead of quit try "exit -f -code 5".

Note Modelsim uses 1 to 231 for their own error messages so I would use a number above 256.

added: Both quit and exit seems to work OK for me, might be a version issue? I used Modelsim 2019.4 and Python 3.7.1. Here is the code I used:

Python code:

` import sys
import subprocess

def main(argv):
    status = subprocess.call([r"vsim.exe", "-c", "-do", "run.do"])
    print("vsim returned",status)    
    sys.exit(status)

if __name__ == '__main__':    
    main(sys.argv[1:])`

run.do file:

vsim top run 1 us quit -f -code 34

CMD batch file:

python callvsim.py @echo Python returned %ERRORLEVEL%

And the output:

Errors: 0, Warnings: 0 vsim returned 34 Python returned 34

Good luck,

Hans