Problem to interrupting process

[DJ_Depannage]

Hello People,

I have problem with my script and I need your help please

i use this :

and push button with Arduino card connect to bluetooth with Raspberry

With library from HZELLER RPI-RGB-LED-MATRIX

Python does not execute any command while a text is displayed on the matrice.
Of course, if I manually call the python file to send the SIGINT signal, everything works.

Could you give me an additional indication to solve this problem please ?

ser = serial.Serial('/dev/rfcomm0', 9600) // Connect to the bluetooth
while True:
	result = ser.read()
	print(result)	           	

         if result == 'f' : 		
    		
		os.system("sudo python ./30.py") // It's display the text on the matrice (library from HZELLER). I Need to do CTRL+C to stop the process.
		
         if result == '7' : 		
    		
		os.system("sudo python ./killprocess.py") // It's not execute because 30.py is launched

[DJ_Depannage]

I will try to be clearer:

I have his files:
file1.py -> I get the data in bluetooth
file2.py -> Send the text to the matrix.
file3.py -> I have to do CTRL-C to clear the matrix, it's obligatory if I want to display another text.

file4.py -> I prepared this code

pid = int (subprocess.Popen (['pgrep', 'python'], stdout = subprocess.PIPE) .stdout.readline () [: - 1])
os.killpg (os.getpgid (pid), signal.SIGINT)

If I manually run the file file4.py, the statement arrives at the file file3.py.
I need to automate the execution of file4.py when I send a new text to the matrix. But how ?