# Crontab ## What's crontab? The cron command-line utility is a job scheduler on Unix-like operating systems. Users who set up and maintain software environments use cron to schedule jobs (commands or shell scripts), also known as cron jobs, to run periodically at fixed times, dates, or intervals.
Format ```java Min Hour Day Mon Weekday * * * * * {command to be executed} ┬ ┬ ┬ ┬ ┬ │ │ │ │ └─ Weekday (0=Sun .. 6=Sat) │ │ │ └────── Month (1..12) │ │ └─────────── Day (1..31) │ └──────────────── Hour (0..23) └───────────────────── Minute (0..59) ```
*** | Operators | Description | | :-------: | :--------------------------: | | `*` | `all values` | | `,` | `separate individual values` | | `-` | `a range of values` | | `/` | `divide a value into steps` | ***
Crontab ```bash # Adding tasks easily echo "@reboot echo hi" | crontab ``` ```bash # Open in editor crontab -e ``` ```bash # List tasks crontab -l [-u user] ```
*** ## Examples
Format exampleDescription
0 * * * *
every hour
*/15 * * * *
every 15 minutes
0 */2 * * *
every 2 hours
0 18 * * 0-6
every week Mon-Sat at 6pm
10 2 * * 6,7
every Sat and Sun on 2:10am
0 0 * * 0
every Sunday midnight
@reboot
every reboot