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How To Stop Strange Cron Jobs Taking Up 100% of CPU on Ubuntu 18 LTS Server

Ubuntu 18

In this article, we will delve into how to deal with strange cron jobs that are taking up 100% of CPU on an Ubuntu 18 LTS server. We will cover how to identify these jobs, how to stop them, and some preventive measures to avoid similar issues in the future.

Quick Answer

To stop strange cron jobs taking up 100% of CPU on an Ubuntu 18 LTS server, you need to identify the problematic cron job using the top command, investigate it in the crontab files, and then either comment out or remove the line in the crontab file to stop the job from running. Preventive measures include keeping your system secure by regularly updating it, installing software from trusted sources, limiting sudo privileges, and monitoring for unusual activity.

Identifying the Problem

The first step is to identify the cron jobs that are causing high CPU usage. You can do this by using the top command, which provides a dynamic real-time view of the running system.

top

In the output, you will see a list of processes with their corresponding CPU usage. If a cron job is consuming a lot of CPU, it will be listed here.

Investigating the Cron Jobs

Once you have identified the problematic cron job, the next step is to investigate what it is doing. Cron jobs in Ubuntu are stored in the /etc/crontab file or in individual user crontab files, which can be accessed with the crontab -l command.

crontab -l

This command will list all the cron jobs for the current user. If you see any suspicious entries related to the high CPU usage, this is a good place to start your investigation.

Stopping the Cron Jobs

To stop a cron job, you can either comment it out in the crontab file by adding a # at the beginning of the line, or you can remove the line entirely. To edit the crontab file, use the crontab -e command.

crontab -e

Remember to save the file after making your changes. The cron job will stop running after you save the file.

Preventive Measures

To prevent such issues in the future, it’s important to keep your system secure. Here are some tips:

  • Regularly update your system to ensure you have the latest security patches.
  • Only install software from trusted sources.
  • Limit the number of users who have sudo privileges.
  • Regularly monitor your system for any unusual activity.

Conclusion

Dealing with strange cron jobs that take up 100% of CPU can be a challenging task, but with the right tools and knowledge, you can identify and stop these jobs effectively. Always remember to keep your system secure to prevent such issues in the future.

For more detailed information on how to manage cron jobs in Ubuntu, you can refer to the official Ubuntu documentation.

How can I identify the cron jobs that are causing high CPU usage?

You can use the top command to identify the cron jobs that are consuming high CPU. It provides a real-time view of the running system, including the CPU usage of each process.

Where are the cron jobs stored in Ubuntu?

Cron jobs in Ubuntu are stored in the /etc/crontab file or in individual user crontab files. You can access the user crontab files using the crontab -l command.

How can I stop a cron job?

To stop a cron job, you can either comment it out in the crontab file by adding a # at the beginning of the line, or you can remove the line entirely. Use the crontab -e command to edit the crontab file.

What preventive measures can I take to avoid similar issues in the future?

To prevent similar issues in the future, it is important to keep your system secure. Regularly update your system, install software from trusted sources, limit sudo privileges, and monitor your system for any unusual activity.

Where can I find more detailed information on managing cron jobs in Ubuntu?

You can refer to the official Ubuntu documentation for more detailed information on managing cron jobs in Ubuntu.

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