How do I activate a python program at exact whole hours? (12:00:00pm, 04:00:00am)

I want to write a program that keeps running in the background and performs a certain task at each hour of the day. How do I achieve this?

Answer

for production i would add cron or schedule

# Schedule Library imported
import schedule
import time
  
# Functions setup
def sudo_placement():
    print("Get ready for Sudo Placement at Geeksforgeeks")
  
def good_luck():
    print("Good Luck for Test")
  
def work():
    print("Study and work hard")
  
def bedtime():
    print("It is bed time go rest")
      
def geeks():
    print("Shaurya says Geeksforgeeks")
  
# Task scheduling
# After every 10mins geeks() is called. 
schedule.every(10).minutes.do(geeks)
  
# After every hour geeks() is called.
schedule.every().hour.do(geeks)
  
# Every day at 12am or 00:00 time bedtime() is called.
schedule.every().day.at("00:00").do(bedtime)
  
# After every 5 to 10mins in between run work()
schedule.every(5).to(10).minutes.do(work)
  
# Every monday good_luck() is called
schedule.every().monday.do(good_luck)
  
# Every tuesday at 18:00 sudo_placement() is called
schedule.every().tuesday.at("18:00").do(sudo_placement)
  
# Loop so that the scheduling task
# keeps on running all time.
while True:
  
    # Checks whether a scheduled task 
    # is pending to run or not
    schedule.run_pending()
    time.sleep(1)