Crontab scheduled task common commands

One 、 Common commands

1、 see crontab Task list

crontab -l

2、 edit crontab Scheduled tasks

crontab -e

3、 Delete crontab Timing task

crontab -r

4、 Relevant command ：

systemctl start crond.service # Start the service

systemctl stop crond.service # Close the service

systemctl status crond.service # View service status

systemctl restart crond.service # Restart the service

Two 、 Timed syntax

crontab A time expression ：

The basic format :

*　　*　　*　　*　　*　　command

branch 　 when 　 Japan 　 month 　 Zhou 　 command

Let's start with an example . Every morning 1:00 Execute the backup program ：0 1 * * * /root/backup.sh . among /root/backup.sh This is the script path , To use absolute paths , For the previous date format, please look directly at the figure below

crontab And operators , It needs to be used to realize some complex time setting . Operators have ：

1、* All numbers in the range , On behalf of all .

2、/ How many numbers are passed , Represents every n Long-term .

3、- from X To Z , For a period of time .

4、, Hash numbers , Represents splitting multiple values .

If you still don't understand the code formula , You can use this online Cron Expression generator ：http://cron.qqe2.com/

3、 ... and 、20 Classic examples

Remember to replace it with your own script path . Please add... To the first line of the corresponding script #!/bin/bash, Otherwise, the script cannot be executed in the scheduled task .

example 1： Every time 1 Once per minute

* * * * * /root/backup.sh

example 2： At the end of every hour 3 Minutes and the 15 Once per minute

3,15 * * * * /root/backup.sh

example 3： Daily 8 Point to 11 Point of the first 3 And the 15 Once per minute

3,15 8-11 * * * /root/backup.sh

example 4： Every other morning 8 Point to 11 Point of the first 3 And the 15 Once per minute

3,15 8-11 */2 * * /root/backup.sh

example 5： One morning a week 8 Point to 11 Point of the first 3 And the 15 Once per minute

3,15 8-11 * * 1 /root/backup.sh

example 6： Every night 21:30 Do it once

30 21 * * * /root/backup.sh

example 7： monthly 1、10、22 Japanese 4 : 45 Do it once

45 4 1,10,22 * * /root/backup.sh

example 8： Every Saturday 、 Sunday's 1 : 10 Do it once

10 1 * * 6,0 /root/backup.sh

example 9： Every day 18 : 00 to 23 : 00 Between every 30 Once per minute

0,30 18-23 * * * /root/backup.sh

example 10： Every Saturday night 23: 00 pm Do it once

0 23 * * 6 /root/backup.sh

example 11： Every hour

* */1 * * * /root/backup.sh

example 12： Every night 23 From o'clock to the next morning 7 Between points , It is performed every hour

* 23-7/1 * * * /root/backup.sh

example 13： On the first day of each week （ That is, every Sunday night 24：00 Start execution ）.

@weekly /root/backup.sh

example 14： Monthly 15 Once a day .

0 11 15 * * /root/backup.sh

example 15： On the first day of each month （ I.e. monthly 1 Early morning 0 Start at ）.

@monthly /root/backup.sh

example 16： Execute once in the specified month （ stay 1 month ,4 The month and 6 Every night in June 0 Click to execute once ）.

0 0 * jan,apr,jun * /root/backup.sh

example 17： Execute once after restart .

@reboot /root/backup.sh

example 18： Send an email notification after the scheduled task is executed .

MAILTO="raj"

1 1 * * * /root/backup.sh

example 19： Appoint shell （ The default is /bin/bash）

SHELL=/bin/sh

1 1 * * * /root/backup.sh

example 20： Specify environment variables .

PATH=/sbin:/bin:/usr/sbin:/usr/bin

1 1 * * * /root/backup.sh