What does the cron expression 0 4 * * * mean?

The cron expression 0 4 * * * schedules a job to run daily at 4 AM. The five fields represent: minute, hour, day of month, month, and day of week.

How do I schedule a cron job to run daily at 4 AM?

Add this line to your crontab: 0 4 * * * /path/to/command. Open your crontab for editing with crontab -e and paste the expression followed by your command.

How do I monitor a cron job that runs daily at 4 AM?

Add a heartbeat check: 0 4 * * * /path/to/script.sh && curl -fsS https://cronsignal.io/ping/YOUR_CHECK_ID. You'll be alerted if the job doesn't run on schedule.

Cron Job Every Day at 4am — 0 4 * * *

Understanding the Expression

The cron expression 0 4 * * * breaks down as follows:

Field	Value	Meaning
Minute	0	At minute 0
Hour	4	At 4:00
Day of month	*	Every day of the month
Month	*	Every month
Day of week	*	Every day of the week

Example Usage

Basic crontab entry

0 4 * * * /path/to/your/script.sh

With output logging

0 4 * * * /path/to/script.sh >> /var/log/script.log 2>&1

With monitoring

0 4 * * * /path/to/script.sh && curl -fsS https://cronsignal.io/ping/YOUR_CHECK_ID

Common Use Cases for Daily at 4 AM

Database backups: Create daily database snapshots
Log rotation: Archive and compress old log files
Daily reports: Generate and email daily summary reports
Data aggregation: Compile daily statistics and metrics

Platform Equivalents

The same schedule expressed across common platforms and schedulers:

Platform	Syntax
Linux crontab	`0 4 * * *`
GitHub Actions	`- cron: '0 4 * * *'`
systemd timer	`OnCalendar=--* 04:00:00`
Kubernetes CronJob	`schedule: "0 4 * * *"`
AWS EventBridge	`cron(0 4 * * ? *)`

Timezone Considerations

4 AM UTC equals 11 PM EST or 8 PM PST. A classic off-peak maintenance window. For 4 AM local EST, use 0 9 * * * UTC.

Common Mistakes

Cloud maintenance overlap: Many providers run maintenance between 2-6 AM UTC. Add retry logic for critical tasks.
Database backup contention: 4 AM UTC is a popular backup window. Check for lock contention if your job touches a database.
Verify runtime before business hours: A 4 AM job taking 6 hours still runs at 10 AM UTC. Profile runtime and alert on overruns.

Cron Daily at 4 AM