How to read linux crontab error log

How to view the crontab error log in Linux: 1. View the file directory "/var/log/cron"; 2. Real-time file tail viewing through the "tail -f /var/log/cron" command; 3. . Use the "vim /var/log/cron" command to view it through an advanced text viewer.

The operating environment of this tutorial: linux5.9.8 system, DELL G3 computer

How to read the linux crontab error log?

View crontab log error in Linux

文件目录  /var/log/cron
 
#实时文件尾部查看
tail -f /var/log/cron
 
#高级文本查看器
vim /var/log/cron

Related introduction:

Linux crontab is a command used to execute programs regularly.

After the operating system is installed, this task scheduling command will be started by default.

The crond command will periodically check whether there is work to be performed every minute. If there is work to be performed, it will be automatically executed.

Note: The newly created cron task will not be executed immediately. It will take at least 2 minutes before it can be executed. Of course, you can restart cron to execute it immediately.

The work of Linux task scheduling is mainly divided into the following two categories:

1. Work performed by the system: work to be performed periodically by the system, such as backing up system data and cleaning cache

2. Work performed by individuals: tasks that a user must do regularly, such as checking the mail server every 10 minutes to see if there are new messages. These tasks can be set by each user themselves

Syntax

crontab [ -u user ] file

or

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

Description:

crontab is used to allow users to execute programs at a fixed time or fixed interval. In other words, it is similar to the user's schedule. surface.

-u user refers to setting the schedule of the specified user. The premise is that you must have its authority (for example, root) to specify the schedule of others. If -u user is not used, it means setting your own schedule.

Parameter description:

-e: Execute a text editor to set the schedule. The default text editor is VI. If you want to use another text editor, please first 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 time format 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 the month, and f5 represents the day of the week. . program represents the program to be executed.

When f1 is *, it means the program will be executed every minute, when f2 is *, it means the program will be executed every hour, and so on

When f1 is a-b, it means from minute a It will be executed within the period up to the b-th minute. When f2 is a-b, it means that it will be executed from the a-th hour to the b-th hour, and so on.

When f1 is */n, it means every n-minute time interval. Executed once, if f2 is */n, it means executed once every n hours, and so on.

When f1 is a, b, c,..., it means the a, b, c,... Minutes to be executed, when f2 is a, b, c,..., it means that the a, b, c...th hour to be executed, and so on

*    *    *    *    *
-    -    -    -    -
|    |    |    |    |
|    |    |    |    +----- 星期中星期几 (0 - 6) (星期天 为0)
|    |    |    +---------- 月份 (1 - 12) 
|    |    +--------------- 一个月中的第几天 (1 - 31)
|    +-------------------- 小时 (0 - 23)
+------------------------- 分钟 (0 - 59)

Users can also set all settings first Store it in a file and use crontab file to set the execution time.

Recommended learning: "Linux Video Tutorial"

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