The Ultimate Developer Guide to Linux Crontab Schedules & Cron Syntax
In Unix and Linux systems administration, DevOps pipelines, and cloud automation, the cron daemon executes background jobs and maintenance scripts on fixed schedules. A crontab (cron table) configuration string controls the exact cadence of recurring backups, telemetry reporting, log rotations, and batch jobs.
Our Crontab Generator & Schedule Builder runs 100% client-side inside your browser sandbox. Your proprietary server commands, shell script paths, and automation schedules are parsed locally without transmitting any data to remote endpoints.
1. The 5-Field Linux Cron Expression Anatomy
| Position | Field Name | Allowed Values | Special Characters Allowed | Example Value |
|---|---|---|---|---|
| 1st | Minute | 0 – 59 | * , - / |
*/15 (every 15 min) |
| 2nd | Hour | 0 – 23 (24-hr clock) | * , - / |
0 (midnight), 2,14 |
| 3rd | Day of Month | 1 – 31 | * , - / L |
1,15 (1st and 15th) |
| 4th | Month | 1 – 12 or JAN – DEC | * , - / |
* (every month), 1-6 |
| 5th | Day of Week | 0 – 7 (0 & 7 = Sun) or SUN – SAT | * , - / |
1-5 (Mon through Fri) |
2. Popular Crontab Presets and Shortcuts
* * * * *— Runs every single minute continuously.0 * * * *— Runs at minute zero of every hour (hourly).0 0 * * *(or@daily) — Runs every day at 00:00 midnight.0 0 * * 0(or@weekly) — Runs every Sunday midnight.0 0 1 * *(or@monthly) — Runs on the 1st of every month at midnight.@reboot— Runs once immediately upon system boot/startup.
3. Step-by-Step Server Crontab Deployment
1. In this generator, select Hours: 02 (2:00 AM) and Minutes: 00 (expression: 0 2 * * *).
2. Open your server terminal and edit the cron configuration: crontab -e.
3. Append the full path command: 0 2 * * * /usr/local/bin/pg_dump dbname > /backups/db.sql 2>&1.
4. Save and exit. Confirm the active job with crontab -l.