Monitor Scheduled Tasks on Windows and Linux

Whether you're running Windows Task Scheduler or Linux cron, scheduled tasks need monitoring. This guide covers both platforms with practical examples for reliable alerting.

Linux: Cron Job Monitoring

Basic Cron Monitoring

Add a heartbeat ping to your cron entry:

# Before
0 2 * * * /home/user/backup.sh

# After
0 2 * * * /home/user/backup.sh && curl -fsS https://wizstatus.com/ping/TOKEN

Wrapper Script Approach

Create a reusable wrapper:

#!/bin/bash
# /usr/local/bin/cron-monitor

PING_URL="$1"
shift

# Run the command
"$@"
EXIT_CODE=$?

# Ping on success
if [ $EXIT_CODE -eq 0 ]; then
  curl -fsS --retry 3 "$PING_URL"
fi

exit $EXIT_CODE

Usage:

0 2 * * * /usr/local/bin/cron-monitor https://wizstatus.com/ping/TOKEN /home/user/backup.sh

Systemd Timers (Modern Linux)

For systemd-based systems, use timer units:

# /etc/systemd/system/backup.service
[Unit]
Description=Daily Backup

[Service]
Type=oneshot
ExecStart=/home/user/backup.sh
ExecStartPost=/usr/bin/curl -fsS https://wizstatus.com/ping/TOKEN

# /etc/systemd/system/backup.timer
[Unit]
Description=Run backup daily

[Timer]
OnCalendar=*-*-* 02:00:00
Persistent=true

[Install]
WantedBy=timers.target

Enable with:

systemctl enable --now backup.timer

Windows: Task Scheduler Monitoring

Method 1: PowerShell Wrapper

Create a PowerShell wrapper script:

# C:\Scripts\Task-Monitor.ps1

param(
    [string]$PingUrl,
    [string]$ScriptPath,
    [string[]]$Arguments
)

try {
    # Run the actual script
    if ($Arguments) {
        & $ScriptPath @Arguments
    } else {
        & $ScriptPath
    }

    # Ping on success
    if ($LASTEXITCODE -eq 0 -or $LASTEXITCODE -eq $null) {
        Invoke-WebRequest -Uri $PingUrl -Method GET -UseBasicParsing | Out-Null
    }
}
catch {
    Write-Error $_.Exception.Message
    exit 1
}

In Task Scheduler, configure:

Program: powershell.exe
Arguments: -ExecutionPolicy Bypass -File "C:\Scripts\Task-Monitor.ps1" -PingUrl "https://wizstatus.com/ping/TOKEN" -ScriptPath "C:\Scripts\backup.ps1"

Method 2: Batch File Wrapper

@echo off
REM C:\Scripts\task-wrapper.bat

SET PING_URL=%1
SHIFT
SET COMMAND=%*

REM Run the command
CALL %COMMAND%

REM Check exit code and ping
IF %ERRORLEVEL% EQU 0 (
    curl -s "%PING_URL%"
)

Method 3: Post-Action in Task Scheduler

Add a second action to your task:

Open Task Scheduler
Edit your task
Go to Actions tab
Add New Action:
- Program: curl.exe
- Arguments: -s https://wizstatus.com/ping/TOKEN

Note: This runs regardless of first action's result. Use wrapper for conditional pinging.

Installing curl on Windows

Modern Windows 10/11 includes curl. For older systems:

# Using winget
winget install curl

# Or use PowerShell's Invoke-WebRequest
Invoke-WebRequest -Uri $URL -Method GET

Cross-Platform Solutions

Python Script

Works on both Windows and Linux:

#!/usr/bin/env python3
# monitor-task.py

import subprocess
import sys
import requests

def main():
    ping_url = sys.argv[1]
    command = sys.argv[2:]

    try:
        result = subprocess.run(command, check=True)

        if result.returncode == 0:
            requests.get(ping_url, timeout=30)

    except subprocess.CalledProcessError as e:
        print(f"Command failed: {e}")
        sys.exit(1)
    except requests.RequestException as e:
        print(f"Ping failed: {e}")

if __name__ == "__main__":
    main()

Usage:

# Linux
python3 monitor-task.py https://wizstatus.com/ping/TOKEN /path/to/script.sh

# Windows
python monitor-task.py https://wizstatus.com/ping/TOKEN C:\Scripts\backup.bat

Configuring Heartbeat Monitors

Linux Cron

For a daily job at 2 AM:

Schedule: Daily at 02:00
Grace period: 60 minutes (for job duration + buffer)
Timezone: Match server timezone

Windows Task Scheduler

For a weekly backup on Sunday at 3 AM:

Schedule: Weekly on Sunday at 03:00
Grace period: 120 minutes
Timezone: Match server timezone

Best Practices

Use Absolute Paths

Cron and Task Scheduler may have different PATH:

# Bad
0 2 * * * backup.sh && curl https://ping-url

# Good
0 2 * * * /home/user/backup.sh && /usr/bin/curl https://ping-url

Log Everything

# Linux
0 2 * * * /home/user/backup.sh >> /var/log/backup.log 2>&1 && curl $PING_URL

# Windows
Start-Transcript -Path "C:\Logs\backup.log" -Append

Handle Failures Gracefully

#!/bin/bash
set -e  # Exit on any error

do_backup
do_verification
do_cleanup

# Only reached if all succeeded
curl $PING_URL

Test After Configuration

Run tasks manually to verify:

# Linux
/home/user/backup.sh && curl $PING_URL

# Windows (Run as the service account)
runas /user:SYSTEM "C:\Scripts\backup.bat"

Troubleshooting

Linux: Job Not Running

Check:

# Is cron running?
systemctl status cron

# Check cron logs
grep CRON /var/log/syslog

# Verify crontab
crontab -l

Windows: Task Not Running