Shulou(Shulou.com)06/01 Report--

First, check whether the cron package is installed:

Rpm-qa | grep cron

2. Confirm whether the crond service is set to boot

Service crond status starts and shuts down levels 3 and 5 crond service chkconfig-- level 35 crond onchkconfig-- level 35 crond off

III. Crond configuration files and log files

Use the crontab-e command to customize the task schedule for the current user, which generates files to / var/spool/cron/$USER

The crond service scans all files in the / var/spool/cron directory every minute to execute the instruction information in the file.

Fourth, prepare the crontab task plan

Crontab file format

Execute orders in time, day, month and week

Case: execute the script every 10s

* / 1 * sleep 10s & & script.sh*/1 * sleep 20s & & script.sh*/1 * sleep 30s & & script.sh*/1 * sleep 40s & & script.sh*/1 * sleep 50s & & script.sh

Note: here these five will start at the same time, so the script will be executed every 10s.

Example:

Execute touch / tmp/a.txt at the 10th minute of every hour

10 * touch / tmp/a.txt

Execute at intervals of 10 minutes

* / 10 * touch / tmp/a.txt

Executed at 10: 30 every night.

30 22 * touch / tmp/a.txt

The 30th minute from 8pm to 10:00 every day.

30 20-22 * touch / tmp/a.txt

Implemented at 10: 30 on January 1 every year.

30 10 1 1 * touch / tmp/a.txt

Execute every two hours

0 * / 2 * echo "Have a break now." > > / tmp/test.txt

First check the crond log:

There are two situations.

First: the mission plan was not carried out at all.

1) restart the crond service.

2) determine whether the task schedule run time is written correctly and whether it is the time we want to execute

Second: the task plan was executed and the called script went wrong.

1) permission issue, whether the file or user has the right to execute

2) relative path absolute path problem in script

3) variable problem of script

4) the path was written incorrectly in the task plan, so that the script was not called at all

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