Cron study notes

In cronlinux, the server that runs the scheduled task executes the specific task according to the time specified in the configuration file. Cron (ubuntu) startup service servicecronstart close service servicecronstop restart service servicecronrestart re-load configuration service...

 

In cron linux, the server that runs the scheduled task executes the specific task according to the time specified in the configuration file.

 

Cron (ubuntu)

 

 

Start service cron start

 

Disable service cron stop

 

Restart service cron restart

 

Reload and configure service cron reload

 

 

 

 

There are two methods to configure cron:

 

1. use the crontab command

 

-U is the specified user

 

 

-E: edit your cron service

 

-L list users' cron services

 

-R: deletes the user's cron service.

 

For example, crontab-u root-e is used to edit the cron task of the root user.

 

 

After entering the editing mode

 

Display: # m h dom mon dow command

 

M indicates minute (0-59)

 

H indicates the hour (0-23)

 

Dom indicates the date (1-31)

 

Mon indicates the month (1-12)

 

Dow indicates that the week (0-6) 0 is Sunday

 

For example:

 

30 16 *** echo "Take care of yourself !" >/Dev/null

 

 

At 04:30, run echo "Take care of yourself !"

 

 

 

 

2. modify the/etc/crontab file

 

Vim is displayed

 

# M h dom mon dow user command

 

User

 

For example: 01 **** root run-parts/etc/cron. hourly

 

 

Execute scripts in/etc/cron. hourly every hour

 

Run-parts indicates executing scripts in the folder.

 

Run-parts can be removed and script commands can be directly added.

 

 

The other method is the same as the first method.