Linux VPS scheduling tasks how to use the crond command

In this article, the editor introduces in detail the "Linux VPS planning task crond command how to use", the content is detailed, the steps are clear, and the details are handled properly. I hope that this "Linux VPS planning task crond command how to use" article can help you solve your doubts, following the editor's ideas slowly in depth, together to learn new knowledge.

First, installation planning tasks

This program may not be preinstalled on some systems and needs to be installed by executing the following command.

Yum install-y vixie-cron

Then start the service

Service crond start

Second, set up scheduled tasks

(1) execute the following command to set the scheduled task:

Crontab-e

The reason for using the above command rather than directly using vi is that cron does a small but necessary syntax check.

(2) set the specification for scheduled tasks:

T1 t2 t3 t4 t5 program

T1 means minutes.

T2 represents hours.

T3 indicates the day of a month.

T4 represents the month

T5 represents the day ordinal of a week.

Program represents the program to run.

(3) some examples:

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

0 * / bin/ls

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

* / 20 6-12 * 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 < / tmp/maildata

00:20, 02:20, 04:20 every day of the month. . Execute echo ""

200-23max 2 * echo ""

The date command is executed every two hours between 11:00 and 8am, and at 8am.

023-7bat 2pm 8 * date

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