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This article mainly explains "how to achieve timing shutdown under linux". The explanation in the article is simple and clear and easy to learn and understand. Please follow the editor's train of thought to study and learn "how to achieve timing shutdown under linux".

Just use the crontab command. Let's take a look at its detailed usage.

Name: crontab

Permissions: all users

Mode of use:

Crontab [- u user] file

Crontab [- u user] {- l |-r |-e}

Description:

Crontab is used to allow users to execute programs at fixed times or at regular intervals, in other words, similar to the user's schedule. -u user means to set a schedule that specifies user, which requires that you have permission (such as root) to specify someone else's schedule. If you don't use-u user, it means to set your own schedule.

Number of meals:

-e: execute a text editor to set the schedule. The internal text editor is VI. If you want to use another text editor, please set the VISUAL environment variable to specify which text editor to use (for example, setenv VISUAL joe).

-r: delete the current schedule

-l: list the current schedule

The format of the schedule is as follows:

F1 f2 f3 f4 f5 program

Where F1 represents minutes, f2 represents hours, f3 represents the day of a month, f4 represents a month, and f5 represents the day of a week. Program represents the program to be executed.

When F1 is *, it means that every minute will be executed. If program,f2 is *, the program will be executed every hour, and so on.

When F1 is aMub, it will be executed from minute a to minute b, and when f2 is amelb, it will be executed from hour a to hour b, and so on.

When F1 is * / n, it is executed every n minutes, f2 is * / n, it is executed every n hours, and so on.

When F1 is a, b, c. It means a, b, c, etc. Minutes to be executed, f2 is a, b, c. It means a, b, c. Hours to execute, other analogies

Users can also store all the settings in the file file and set the schedule in the way of crontab file.

Example:

Execute / bin/ls once a month at the 0th minute of every hour:

0 7 * / bin/ls

/ usr/bin/backup is performed every 20 minutes from 6 a.m. to 12:00 every December:

0 6-12 beat 3 * 12 * / usr/bin/backup

Send a letter to alex@domain.name at 5:00 every day from Monday to Friday:

0 17 * 1-5 mail-s "hi" alex@domain.name

/ dev/null 2 > & 1 is fine.

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