Crontab let Linux execute shell scripts at timed intervals

With Crontab you can execute a shell script or a series of Linux commands at a specified time. For example, the system administrator schedules a backup task to run every day

Entry

# crontab–e

This allows you to open your personal crontab profile in edit mode and then add this line:

XX * * * */home/linrui/xxxxxxxx.sh

This will run the specified. sh file at 00:00 every day.

For scripts that resemble a few minutes of execution, add ">/dev/null 2>&1" at the end, which indicates that the system log is not written:

XX * * * */home/linrui/xxxxxxxx.sh >/dev/null 2>&1

Cron description of each item

The following is the format of the crontab file:

{minute} {Hour} {Day-of-month} {Month} {Day-of-week} {Full-path-to-shell-script}

O minute: Interval is 0–59

O Hour: Interval is 0–23

O Day-of-month: Interval is 0–31

O Month: The interval is 1–12. 1 was January. 12 was December.

O Day-of-week: Interval is 0–7. Sunday can be 0 or 7.

Crontab Example

1. Run at 00:01

* * * */home/linrui/xxxx.sh

2, the backup job every weekday 23:59.

* * 1,2,3,4,5/home/linrui/xxxx.sh

or the following:

* * 1-5/home/linrui/xxxx.sh

3. Run a command every minute

*/1 * * * */home/linrui/xxxx.sh

4, 1th number 14:10 per month to run

* */home/linrui/xxxx.sh

Crontab Options for Commands

The following are the valid options for crontab:

Crontab–e: Modify the crontab file. If the file does not exist, it is created automatically.

Crontab–l: Displays the crontab file.

Crontab-r: Delete the crontab file.

Crontab-ir: Alerts the user before deleting the crontab file.

Reprinted from: https://my.oschina.net/u/2288038/blog/485972

Crontab let Linux execute shell scripts at timed intervals