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Learn Linux Shell Scripting – Fundamentals of Bash 4.4

You're reading from   Learn Linux Shell Scripting – Fundamentals of Bash 4.4 A comprehensive guide to automating administrative tasks with the Bash shell

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Product type Paperback
Published in Dec 2018
Publisher Packt
ISBN-13 9781788995597
Length 452 pages
Edition 1st Edition
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Author (1):
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Sebastiaan Tammer Sebastiaan Tammer
Author Profile Icon Sebastiaan Tammer
Sebastiaan Tammer
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Table of Contents (20) Chapters Close

Preface 1. Introduction FREE CHAPTER 2. Setting Up Your Local Environment 3. Choosing the Right Tools 4. The Linux Filesystem 5. Understanding the Linux Permissions Scheme 6. File Manipulation 7. Hello World! 8. Variables and User Input 9. Error Checking and Handling 10. Regular Expressions 11. Conditional Testing and Scripting Loops 12. Using Pipes and Redirection in Scripts 13. Functions 14. Scheduling and Logging 15. Parsing Bash Script Arguments with getopts 16. Bash Parameter Substitution and Expansion 17. Tips and Tricks with Cheat Sheet 18. Assessments 19. Other Books You May Enjoy

Scheduling with at and cron

We've learned about many things in the world of shell scripting so far: variables, conditionals, loops, redirections, and even functions. In this chapter, we'll explain another important concept that is closely related to shell scripting: scheduling.

Simply put, scheduling is making sure your commands or scripts run at certain times, without the need for you to personally start them every time. A classic example can be found in cleaning up logs; often, older logs are no longer useful and take up too much space. For example, you could fix this with a cleanup script that removes logs older than 45 days. However, such a script should probably be run once a day. On a workday, this shouldn't pose the biggest problem, but having to log in during the weekend is no fun. Actually, we should not even consider this, since scheduling allows us to...

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