CRON JOB – Scheduling Jobs in Linux
Scheduling Jobs in Linux with CRON(CRONTAB)
CRONTAB is a very useful utility in Linux to schedule your day to day jobs.CRONTAB or CRON simply runs commands or scripts at a scheduled time.
In this article, we will learn scheduling Jobs in Linux with CRONTAB. We will take examples to understand it.
Also Read : How to install Jenkins on Ubuntu
&& Create your First Build Job in Jenkins
Below are the important crontab commands that we must know.
1.Add a new Job in CRONTAB
$ crontab -e
This command will open an empty file. You need to put your commands or scripts here to run your command or script automatically at a particular interval of time.
2. Display all Scheduled Jobs in CRONTAB
$ crontab -l
This command will display all scheduled jobs.
- CRONTAB Format
Below is the format of CRONTAB or CRON that we put in CRONTAB – I command.
* * * * * /path/to/script.sh
Here definition of * * * * * are as follows:
|min||hour||day of month||month of year||day of week|
1. A Script is scheduled to run 5:10 AM every day.
2. A Script is scheduled to run 5:10 AM to 5:20 AM every day.
3. A script is scheduled to run every 5 min.
4. A script is scheduled to run at 11 AM on 10th of March
5. A script is scheduled to run at 1 AM every Saturday.
6. A command to restart MySQL service at 10 am every day.
3.Remove current Job in CRONTAB
$ crontab -r
4.Prompt before removing a CRONTAB.
$ crontab -ir
5.Add and display CRON for a particular user.
Use “- u username” after crontab -l or crontab -e to display or edit crontab for a particular user.
$crontab – l -u username
$crontab -e -u username
6.List name of the users who have CRONTAB jobs.
$ ll /var/spool/cron
This article ends here.
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