Automating a Shell Script using Crontab

In this project, we demonstrate how to automate a shell script using crontab on a Linux-based operating system. This guide assumes that you already have a shell script that you want to automate, and a basic understanding of the command line and crontab.

Our shell script will write into mylog.txt file every minute. Shell script :

Prerequisites

• Linux-based operating system (such as Ubuntu)
• Text editor (such as nano or vim)
• Terminal access
• Shell script to automate

Steps

1. Open terminal and run the command crontab -e. This will open the crontab editor.

crontab -e

2. In the editor, add the following line at the end: * * * * * /path/to/script.sh. This sets the cronjob to run the script every minute.

* * * * * /path/to/script.sh

3. Save and close the editor. 4. Check if the cronjob was correctly set by running crontab -l.

crontab -l

5. Wait for a minute and check the output of the shell script in the log file.

Before updating log file :

After updating log file :

Note:

• The path to the script must be the absolute path, not the relative path.
• In the above line, the five stars (* * * * *) represent the schedule of the cronjob, where the first field is for minutes (0-59), the second for hours (0-23), the third for days of the month (1-31), the fourth for months (1-12), and the fifth for days of the week (0-7, both 0 and 7 represent Sunday). You can modify this to run the script at a specific schedule.
• If your script requires environment variables, you need to set them in the crontab file.

Conclusion

In this project, we learned how to automate a shell script using crontab on a Linux-based operating system. We hope this guide will help you automate your own shell script.