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Issue with script that automatically runs at particular time every day

I want a python file to run automatically at 8am every day going forward. I try to use the library schedule as pointed out in the second answer here, in Windows.
import schedule
import time
def query_fun(t):
print('Do a bunch of things')
print("I'm working...", t)
df.to_csv('C:/Documents/Query_output.csv', encoding='utf-8')
schedule.every().day.at("08:00").do(query_fun, 'It is 08:00')
while True:
schedule.run_pending()
time.sleep(60) # wait one minute
But 8am has come and gone, and the csv file hasn't been updated, and it doesn't look like the script runs when I want it to.
Edit: Based on this, I used pythonw.exe to run the script in the command line: C:\Program Files\Python3.7>pythonw.exe daily_query.py but the script doesn't run when expected.

You took out the key part of the script by commenting it out. How is the script magically supposed to rise up at 8 AM to do something? The point is to always keep it running and trigger at the right time using the mechanism provided by schedule library (running any pending jobs at time T on day D that is). What you are doing right now is just declaring the method and exiting without doing anything.
The point is to keep the script running in background and trigger the function by matching the current time with the time specified, running any pending assigned jobs as per your logic. You run your script in background and forget about it until 8 AM:
nohup python MyScheduledProgram.py &
nohup will take care that your terminal doesn’t get any output printed on it from the program. You can view the output from nohup.out though.

Here you can easily see what the skript does:
schedule.every().day.at("08:00").do(query_fun, 'It is 08:00')
tells the scheduler to run the function if it is 8am.
But the other part of the library is this one:
while True:
schedule.run_pending()
time.sleep(60) # wait one minute
this part checks if it should start a skript, then it waits for 60 seconds, and checks again.
EDIT:
The question was related to a Windows machine, therefore my answer has no point here.
If you are on a linux machine, you should consider using crontabs:
Open a terminal and type
crontab -e
After you selected the editor you wanted (lets take nano) it opens a list, where you can add various entries
just add:
0 8 * * * /usr/bin/python3 /home/path/to/skript.py
Then save with STRG + O and exit nano with STRG + X
The skript will run everyday at 8am, just test the command
/usr/bin/python3 /home/path/to/skript.py
to make sure the skript does not produce an error

Python's os.system within a for loop: how to wait for a command to finish before re-starting the loop?

I am new in using os.system (in Python 3) and am trying to execute a program that I would normally run in a Linux terminal. I need to iterate a few times and am using something like the following loop:
for item in item_list:
os.system("gnome-terminal -- program_execute "+item)
The problem is that this loop simutaneously opens n terminal windows (the length of my item_list is n) and executes all of them at the same time. My question is:
How could I run the loop len(item_list) times with the next run starting only after the current one finishes?
I can't use sleep() because the running time varies from item to item and I would like to optimize the process.
EDIT: I've tried using .communicate() and .wait() without success. I would like os.system (or os.subprocess) to understand that the gnome-terminal is still running, only passing by the next element in the loop after gnome-terminal from previous loop has closed.

I used subprocess with the code below and it worked, i.e. the software runs once and finishes completely before going to the next loop.
for item in item_list:
subprocess.call(["gnome-terminal","--disable-factory","--","my_command"])

How can I stop a python script on a batch file

I want to start a python script and then automatically close that script after 2 minutes, run another command, and keep doing the same thing again like this (loop) forever :
Cd c:/location.of.script/
pythonscript.py
Stop (like ctrl+c) pythonscript.py after 120s
Del -f cookies.file
.
.
.
Is this even possible with a batch file on windows 10? If so, can someone please help me with this?
I’ve been looking everywhere but found nothing except the exit() command which stops the script from inside - this isn’t what I want to do.

You can change your python script to exit after 2 minutes, and you could batch file that has a while loop that runs forever and run the python script then deletes the cookie.file, I don't know if that's exactly what you want, but you can do it by putting a timer in your python script.
You can make a separate thread that keeps track of the time and terminates the code after some time.
An example of such a code could be:
import threading
def eternity(): # your method goes here
while True:
pass
t=threading.Thread(target=eternity) # create a thread running your function
t.start() # let it run using start (not run!)
t.join(3) # join it, with your timeout in seconds
And this code is copied from https://stackoverflow.com/a/30186772/4561068

Is on Python 3 any library to relaunch the script?

I have some script in Python, which does some work. I want to re-run this script automatically. Also, I want to relaunch it on any crashes/freezes.
I can do something like this:
while True:
try:
main()
except Exception:
os.execv(sys.executable, ['python'] + sys.argv)
But, for unknown reason, this still crashes or freezes one time in few days. So I see crash, write "Python main.py" in cmd and it started, so I don't know why os.execv don't do this work by self. I guess it's because this code is part of this app. So, I prefer some script/app, which will control relaunch in external way. I hope it will be more stable.
So this script should work in this way:
Start any script
Check that process of this script is working, for example check some file time change and control it by process name|ID|etc.
When it dissapears from process list, launch it again
When file changed more than 5 minutes ago, stop process, wait few sec, launch it again.
In general: be cross-platform (Linux/Windows)
not important log all crashes.
I can do this by self (right now working on it), but I'm pretty sure something like this must already be done by somebody, I just can't find it in Google\Github.
UPDATE: added code from the #hansaplast answer to GitHub. Also added some changes to it: relauncher. Feel free to copy/use it.

As it needs to work both in windows and on linux I don't know a way to do that with standard tools, so here's a DIY solution:
from subprocess import Popen
import os
import time
# change into scripts directory
abspath = os.path.abspath(__file__)
dname = os.path.dirname(abspath)
os.chdir(dname)
while True:
p = Popen(['python', 'my_script.py', 'arg1', 'arg2'])
time.sleep(20) # give the program some time to write into logfile
while True:
if p.poll() != None:
print('crashed or regularly terminated')
break
file_age_in_s = time.time() - os.path.getmtime('output.log')
if file_age_in_s > 60:
print('frozen, killing process')
p.kill()
break
time.sleep(1)
print('restarting..')
Explanation:
time.sleep(20): give script 20 seconds to write into the log file
poll(): regularly check if script died (either crashed or regularly terminated, you can check the return value of poll() to differentiate that)
getmtime(): regularly check output.log and check if that was changed the past 60 seconds
time.sleep(1): between every check wait for 1s as otherwise it would eat up too many system resources
The script assumes that the check-script and the run-script are in the same directory. If that is not the case, change the lines beneath "change into scripts directory"

I personally like supervisor daemon, but it has two issues here:
It is only for unix systems
It restarts app only on crashes, not freezes.
But it has simple XML-RPC API, so It makes your job to write an freeze-watchdog app simplier. You could just start your process under supervisor and restart it via supervisor API when you see it freezes.
You could install it via apt install supervisor on ubuntu and write config like this:
[program:main]
user=vladimir
command=python3 /var/local/main/main.py
process_name=%(program_name)s
directory=/var/local/main
autostart=true
autorestart=true

Can't kill a running subprocess using Python on Windows

I have a Python script that runs all day long checking time every 60 seconds so it can start/end tasks (other python scripts) at specific periods of the day.
This script is running almost all ok. Tasks are starting at the right time and being open over a new cmd window so the main script can keep running and sampling the time. The only problem is that it just won't kill the tasks.
import os
import time
import signal
import subprocess
import ctypes
freq = 60 # sampling frequency in seconds
while True:
print 'Sampling time...'
now = int(time.time())
#initialize the task.. lets say 8:30am
if ( time.strftime("%H:%M", time.localtime(now)) == '08:30'):
# The following method is used so python opens another cmd window and keeps original script running and sampling time
pro = subprocess.Popen(["start", "cmd", "/k", "python python-task.py"], shell=True)
# kill process attempts.. lets say 11:40am
if ( time.strftime("%H:%M", time.localtime(now)) == '11:40'):
pro.kill() #not working - nothing happens
pro.terminate() #not working - nothing happens
os.kill(pro.pid, signal.SIGINT) #not working - windows error 5 access denied
# Kill the process using ctypes - not working - nothing happens
ctypes.windll.kernel32.TerminateProcess(int(pro._handle), -1)
# Kill process using windows taskkill - nothing happens
os.popen('TASKKILL /PID '+str(pro.pid)+' /F')
time.sleep(freq)
Important Note: the task script python-task.py will run indefinitely. That's exactly why I need to be able to "force" kill it at a certain time while it still running.
Any clues? What am I doing wrong? How to kill it?

You're killing the shell that spawns your sub-process, not your sub-process.
Edit: From the documentation:
The only time you need to specify shell=True on Windows is when the command you wish to execute is built into the shell (e.g. dir or copy). You do not need shell=True to run a batch file or console-based executable.
Warning
Passing shell=True can be a security hazard if combined with untrusted input. See the warning under Frequently Used Arguments for details.
So, instead of passing a single string, pass each argument separately in the list, and eschew using the shell. You probably want to use the same executable for the child as for the parent, so it's usually something like:
pro = subprocess.Popen([sys.executable, "python-task.py"])