how to stop and start a script for 30 seconds

[snippsat]

schedule work fine for this.
You could probably do all in Python,and drop the the shell script.
Here a example of making a file then delete,run_sh example on how to call shell script with subprocess.

import schedule
import time, os
import subprocess

def make_file():
    fn = 'test.out'
    open(fn, 'a').close()
    print(f'Making <{fn}>')

def del_file():
    try:
        fn ='test.out'
        os.remove(fn)
        print(f"Removed <{fn}>")
    except FileNotFoundError:
        print(f'Could not find <{fn}>')

def run_sh():
    '''Example running shell script'''
    subprocess.run(['bash', 'start.sh'])

schedule.every(8).seconds.do(make_file)
schedule.every(12).seconds.do(del_file)
while True:
    schedule.run_pending()
    time.sleep(1)

Output:
λ python remove_file.py
Making <test.out>
Removed <test.out>
Making <test.out>
Removed <test.out>
Making <test.out>
Making <test.out>
Removed <test.out>
Making <test.out>