Cron is the daemon that can be used to schedule tasks according to time, day of the month, month, day of the week, and week.

In order to use cron you must have:

1. a package vixie-cron installed.
To check it type:

rpm -q vixie-cron

2. Daemon crond must be running. To check it type:

service crond status

To install crond on Centos type:

yum install vixie-cron

If you want to add some task to cron you must place it in the file


Sample crontab config:


# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name command to be executed
01 00 * * thu,sat root /scripts/./backupvm

Scheduled task is a script ./backupvm which is in folder /scripts. Script is starting as root at 0:01 any day of month, any month, but two days a week: THU an SAT.

On some OS distros you should use

crontab -e

command to edit cron tasks. You can switch to your preferred editor. For example to nano:

EDITOR=nano; export EDITOR

After run again "crontab -e" And place the task. For example we apply to start some script every minute:

* * * * * root /./ >>/testlog.log

Every 2 minutes:

*/2 * * * * root /./ >>/testlog.log

Every time when system starts:

@reboot root /./ >>/testlog.log

Was this answer helpful?

 Print this Article

Also Read

Web server

In this guide we will create our own web server on Centos 6.  We will use Apache...

Set hostname

Set host name on Centos: /etc/sysconfig/network   HOSTNAME="mycomputer"...


Installing mysql: yum install mysql-server Enter to mysql: mysql -u user -p password...

Generating public/private ssh keys

How to generate and use public / private ssh keys This guide is tested on Centos 6 To...

Backing up VPS from the inside

This guide will show you how to backup your vsp/container "from the inside vps". First of...