Add Cron Jobs to a Specific User in a Linux System

This article we will teach you to schedule a cron job to be executed at a specific time in a day.

General Syntax of a Cron Job

MIN    HOUR    Day of month    Month    Day of Week    Command
0-59   0-23       1-31          1-12       0-6       linux command or script

To see the list of cron jobs which exists on the machine, run the below command

# crontab -u test1 -l
no crontab for test1

To Add the New Cron Job to Test1 User, run the below Command 

#crontab -u test1 -e
no crontab for test1 - using an empty one
Select an editor. To change later, run 'select-editor'.
/bin/ed
/bin/nano <---- easiest
/usr/bin/vim.basic
/usr/bin/vim.tiny
Choose 1-4 [2]:2
# Edit this file to introduce tasks to be run by cron.
#
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
#
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').#
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
#
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
#
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
#
# For more information see the manual pages of crontab(5) and cron(8)
#
# m h dom mon dow command

Scheduling a Job for a different user

The basic usage of cron is to execute a job in a specific time as shown below. This will execute the Full backup shell script (backup_files.sh) on Every day at 9 AM and 6 PM

00 09-18 * * * /home/test1/backup_files.sh

Explanation

00 – 00th Minute
09-18 – 09 AM & 06:00PM
* --Every day of the Month
* -- Every Month.
* --Every day of the week

Conclusion

At the end of the configuration, you should be able to run a script or command at a specific time every day from a particular user. Like this, we can specify Cron jobs to any user. These type of Crons are generally used to take a backup of the users data such as Desktop, Downloads etc.