Scheduled Tasks for Linux

First, check the related services

1. Check Crond Service

Service Crond Status

Installation Services

Yum Install Vixie-cron

2. Check the crontab Configuration tool

Crontab-l

Installing crontab

Yum Install Crontabs

Second, set up the Scheduled tasks

1. View existing Plans

[Email protected] ~]# crontab-l/*1date >>/tmp/log.txt*/1  SleepDate >>/tmp/log.txt

Each row represents a plan. There are 5 on the left of each row * indicates the code to be executed to the right of the scheduled execution time.

Explanation of 5 * In the crontab configuration file.

[Email protected] ~]#Cat/etc/crontab SHELL=/bin/Bashpath=/sbin:/bin:/usr/sbin:/usr/Binmailto=Roothome=/# for details seeMans 4crontabs# Example of Job definition:#.----------------Minute (0- -)# | .-------------Hour (0- at)# |  | .----------Day of Month (1- to)# |  |  | .-------Month (1- A) OR jan,feb,mar,apr ... #|  |  |  | .----Day of Week (0-6) (sunday=0Or7) OR sun,mon,tue,wed,thu,fri,sat#|  |  |  | |# * * * * * * user-name command to be executed

As you can see from the above explanation, the minimum execution time for each plan can only be set to one execution per minute. So how do you set up a schedule that executes every 30s, by setting two identical plans, but the second one will sleep 30s at the time of execution.

2. Editorial Plan

Crontab-e

3. Here are a few simple examples

Executes once per minute.

* * * * * command

Executes every 30 minutes.

0, * * * * command

Every day from 9 to 10 points in the first 1 minutes of execution.

1 9-Ten * * * command

Every 2 days, 10 points of the first 1 minutes of execution.

1 Ten */2 * * command

4. Special symbolic interpretation of the above example

*: represents all possible values.

,: Specify a list range, for example, "1,3,5,7,9"

-: Specifies an integer range, for example, "1-5" for "1,2,3,4,5"

/: The interval frequency of the specified time, for example, "0-23/2", is performed every two hours.

5. View the log for scheduled execution

cat /var/log/: run-parts localhost(/etc/cron.daily ) [1277]: finished logrotate

Third, the matters needing attention

1. Write global path when file path is involved in command.

2, the system automatically perform task scheduling, is not loaded any environment variables.

Scheduled Tasks for Linux