Crontab overview
What is crontab
Crontab is a toll to schedule commands. You can run your terminal command on a specific schedule like run a command every day or every weekends.
Basic command
crontab [-u user] {-l | -e | -r}
| command | utility |
|---|---|
| -l | list your cron job |
| -r | remove your cron job |
| -e | edit your cron job |
| -u | specific a user |
How to schedule a command
Cron job looks like:
# ┌───────────── minute (0 - 59)
# │ ┌───────────── hour (0 - 23)
# │ │ ┌───────────── day of month (1 - 31)
# │ │ │ ┌───────────── month (1 - 12)
# │ │ │ │ ┌───────────── day of week (0 - 6) (Sunday to Saturday;
# │ │ │ │ │ 7 is also Sunday on some systems)
# │ │ │ │ │
# │ │ │ │ │
# * * * * * command_to_execute
# export date into a file every minutes
* * * * * date >> ~/Desktop/test.txt
# Mon to Fri, 2:00, 2:30 , 4:00, 4:30
*/30 2,4 * * 1-5 echo "hello world"| symbol | meaning |
|---|---|
| * | any value |
| , | value list separator |
| - | range of value |
| / | step values |
crontab.guru
crontab.guru which is a website to check whether your schedule is correct.
Reference
Thanks Corey Schafer’s video