crontab

Why is my Crontab not working, and how can I troubleshoot it?

We all know that Cron or Crontab works as the best job scheduler for the Linux-based system. Whenever you wish to run certain time-bound operations, you can always take the services of the Cron daemon. However, at times, your Crontab might stop working, and you might wonder why? Also, in such situations, you are willing to try out all the possible ways to fix this issue. Therefore, we have dedicated today’s article to the issues that cause a hindrance in the proper working of the Crontab and how they can be troubleshot.

Why is my Crontab not working?

Certain reasons can cause your Crontab to fail. The first and foremost one is that your Cron daemon might not be working for some reason which will consequently cause your Crontab to fail. The environment variables of your system might not have been properly set up. There can be some errors in the script that you are trying to execute with your Crontab. For example, the desired script might be missing Shebang, i.e., the necessary character sequence at the start of the script. The script you are trying to execute with Crontab might not be executable, i.e., its permissions are restricted. The path of the script that you are trying to execute might be incorrect. You might be missing out on the extension of the file that you are trying to execute with Crontab.

How can I Troubleshoot my Faulty Crontab?

Depending upon the actual cause of the Crontab failure, there are different ways to perform troubleshooting. Some of these ways are listed below:

First, you need to ensure that the Cron daemon is active and running in the background. This can be done simply by checking its status with the following command:

$ sudo systemctl status cron

Check the path of the command or the file that you are trying to execute with Crontab and ensure if it is correct.

Ensure that you have provided the exact name of the file or the command you are trying to execute. Moreover, it would be best to make sure that the file or script you are trying to execute has the relevant permissions set up.

If you want to write Cron jobs for the current user, then you must access the Crontab file of the current user with the command shown below:

$ crontab –e

If you write the “sudo” keyword before this command, it will open up the root user’s Crontab file, and the jobs you will write in it will not be executed for the current user; rather, they will be executed for the root user. This thing should especially be taken care of while writing Cron jobs.

Try running your desired script through the terminal to figure out if there are some issues with your script or fail only because of Crontab.

Also, make sure not to skip Shebang while creating your scripts.

Check the Crontab logs with the following command to troubleshoot for errors:

$ cat /var/log/cron.log

Ensure that the syntax of the Cron job that you have listed in your Crontab file is correct.

Make sure to provide the relevant file extensions while executing them as Cron jobs.

Conclusion:

In this article, we did an open-ended discussion on the various issues that can cause your Crontab to fail. After digging deeper into those causes, we shared with you some of the most common and quick methods of troubleshooting these issues for fixing your Crontab immediately.

About the author

Karim Buzdar

Karim Buzdar

Karim Buzdar holds a degree in telecommunication engineering and holds several sysadmin certifications. As an IT engineer and technical author, he writes for various web sites. He blogs at LinuxWays.