This folder contains 7 standalone Python scripts, each automating a single, specific task-scheduling need (in-process scheduling, cron, Windows Task Scheduler, periodic execution, one-off timed execution, retry-on-failure, and a background job queue).

Every script:

• Is completely independent — you only need the one file for the task you want.
• Can be run directly from the command line.
• Uses argparse, so running it with -h shows help and usage.
• Prints clear success/error messages so you always know what happened.

Repository: https://github.com/aw-junaid/Python-System-Administration/tree/main/modules/Task%20Scheduling/scripts

1. schedule_with_library.py, execute_periodically.py, and execute_at_specific_time.py only run while the script itself is running. Close the terminal or lose the process and the schedule stops. For jobs that must survive reboots/logouts, use schedule_with_cron.py (Linux/macOS) or windows_task_scheduler.py (Windows) instead — those register with the OS.
2. schedule_with_cron.py modifies your real crontab (the current user's). Run crontab -l before and after to see what changed, and always give jobs a --comment label so you can find and remove them later with the remove action.
3. windows_task_scheduler.py modifies real Windows Task Scheduler entries and may require running your terminal as Administrator for some schedule types or system-level tasks.
4. Commands you schedule run with the same permissions as the user/script that scheduled them. Don't schedule commands from untrusted sources.
5. queue_background_jobs.py's worker actually executes every command in the queue — only add commands you trust, and check job_queue.json/job_queue.log if something unexpected runs.
6. Always test your command manually first (run it directly in the terminal) before scheduling it, so you know it works and know what "success" (exit code 0) looks like.
7. Long-running loops (execute_periodically.py without --count, schedule_with_library.py, queue_background_jobs.py worker without --once) run until you press Ctrl+C — know how to stop them.

• Python 3.9+ installed on your system.
• Check your version:

  python3 --version

• Some scripts use only the Python standard library — nothing to install.
• Others need small external packages, listed in requirements.txt.
• schedule_with_cron.py requires a working cron/crontab installation and is Linux/macOS only.
• windows_task_scheduler.py wraps the built-in schtasks command and is Windows only.

1. Clone the repository:

   git clone https://github.com/aw-junaid/Python-System-Administration.git
   cd "Python-System-Administration/modules/Task Scheduling/scripts"

2. (Recommended) Create a virtual environment:

   python3 -m venv venv
   source venv/bin/activate        # On Windows: venv\Scripts\activate

3. Install dependencies:

   pip install -r requirements.txt

   windows_task_scheduler.py, execute_periodically.py, execute_at_specific_time.py, retry_failed_task.py, and queue_background_jobs.py work with zero installs. schedule_with_library.py needs schedule; schedule_with_cron.py needs python-crontab and croniter.

4. Run any script:

   python3 script_name.py --help

   This shows the exact arguments each script expects.

Below, python3 is used for Linux/macOS. On Windows, use python instead.

Requires: pip install -r requirements.txt

python3 schedule_with_library.py "echo Hello" --every 10 --unit seconds
python3 schedule_with_library.py "python3 backup.py" --every 1 --unit hours

Expected output: Confirms the schedule, then runs the command every N --unit (seconds/minutes/hours/days), printing a timestamp and output each time it fires. Runs until Ctrl+C — the script itself must stay running.

Requires: pip install -r requirements.txt · Platform: Linux/macOS only

python3 schedule_with_cron.py add "0 2 * * *" "python3 /home/user/backup.py" --comment "daily-backup"
python3 schedule_with_cron.py list
python3 schedule_with_cron.py remove --comment "daily-backup"

Expected output:

• add: confirms the job was added to your crontab and shows its next run time.
• list: shows every cron job for your user, with enabled/disabled status.
• remove: confirms how many jobs with that comment/label were deleted.

Verify directly with the standard crontab -l command at any time.

Platform: Windows only

python windows_task_scheduler.py add "DailyBackup" "C:\Python312\python.exe C:\scripts\backup.py" --schedule DAILY --time 02:00
python windows_task_scheduler.py list
python windows_task_scheduler.py remove "DailyBackup"

Expected output:

• add: Task 'DailyBackup' created successfully. (uses schtasks /Create under the hood).
• list: full output of schtasks /Query, showing all scheduled tasks on the system.
• remove: Task 'DailyBackup' removed successfully.

Caution: Some schedule types or system-wide tasks require running your terminal as Administrator.

python3 execute_periodically.py "echo Hello" --interval 5
python3 execute_periodically.py "python3 healthcheck.py" --interval 60 --count 10

Expected output: Runs the command every --interval seconds, printing a timestamp and output each time. With --count, stops automatically after that many runs; without it, runs forever until Ctrl+C.

python3 execute_at_specific_time.py "python3 backup.py" --time 23:30
python3 execute_at_specific_time.py "python3 report.py" --datetime "2026-08-01 09:00:00"

Expected output: Prints the target time and how long it will wait, then blocks until that moment and runs the command once. --time HH:MM schedules for today (or tomorrow if that time already passed); --datetime targets an exact date and time. Ctrl+C cancels before it fires.

python3 retry_failed_task.py "curl -f https://example.com/api/ping"
python3 retry_failed_task.py "python3 upload.py" --max-retries 8 --base-delay 3

Expected output: Runs the command; if it exits non-zero, retries with exponential backoff (delay doubles each attempt, capped at --max-delay, default 60s) up to --max-retries times (default 5). Prints Success on attempt N and exits 0 as soon as it succeeds, or gives up and exits 1 after the final attempt.

python3 queue_background_jobs.py add "python3 convert.py file1.csv"
python3 queue_background_jobs.py add "python3 convert.py file2.csv"
python3 queue_background_jobs.py list
python3 queue_background_jobs.py worker

Expected output:

• add: Job #N added to queue: <command>, stored in job_queue.json.
• list: every job with its status (pending, completed, failed).
• worker: processes pending jobs in order, one at a time, logging each start/output/result to job_queue.log. Use worker --once to drain the current queue and exit; without --once, it keeps polling for new jobs every --interval seconds (default 5) until Ctrl+C.

To safely try these scripts without touching real schedules or system state:

mkdir test_area && cd test_area
python3 ../execute_periodically.py "echo tick" --interval 2 --count 3
python3 ../retry_failed_task.py "python3 -c \"import sys; sys.exit(0)\"" --max-retries 2
python3 ../queue_background_jobs.py add "echo queued job"
python3 ../queue_background_jobs.py worker --once

• These scripts are provided for educational and administrative automation purposes.
• Always review a script's code before scheduling it to run automatically or unattended.
• The author is not responsible for issues caused by scheduled commands, including unintended crontab/Task Scheduler changes, runaway loops, or commands run with incorrect permissions.