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Learn Linux Quickly

You're reading from   Learn Linux Quickly A beginner-friendly guide to getting up and running with the world's most powerful operating system

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Product type Paperback
Published in Aug 2020
Publisher Packt
ISBN-13 9781800566002
Length 338 pages
Edition 1st Edition
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Author (1):
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Ahmed AlKabary Ahmed AlKabary
Author Profile Icon Ahmed AlKabary
Ahmed AlKabary
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Toc

Table of Contents (24) Chapters Close

Preface 1. Your First Keystrokes 2. Climbing the Tree FREE CHAPTER 3. Meet the Editors 4. Copying, Moving, and Deleting Files 5. Read Your Manuals! 6. Hard versus Soft Links 7. Who Is Root? 8. Controlling the Population 9. Piping and I/O Redirection 10. Analyzing and Manipulating Files 11. Let's Play Find and Seek 12. You Got a Package 13. Kill the Process 14. The Power of Sudo 15. What's Wrong with the Network? 16. Bash Scripting Is Fun 17. You Need a Cron Job 18. Archiving and Compressing Files 19. Create Your Own Commands 20. Everyone Needs Disk Space 21. echo "Goodbye My Friend" 22. Assessments 23. Other Books You May Enjoy

Using octal notation

Instead of the letters r, w, and x, you can use the numbers 4, 2, and 1 to set file permissions. Take a look at the following image:

Figure 7: Understanding octal notation

Notice that the first number, 7, is basically the addition of the three numbers: 4 (r) + 2 (w) + 1 (x), which sets full permissions to the file owner. The second number, 6, is the addition of the two numbers: 4 (r) + 2(w), which sets the read and write permissions to the group owner. Finally, the third number, 4, which sets the read permission to others.

I know what you are thinking: "Why would I want to do math when I can just use the literal notation rwx?" And trust me, I feel you. A lot of people prefer the literal notation over the numeric notation, but some people just love numbers way too much!

Let's do some practice with the octal notation. There are currently zero permissions on the file mysmurf:

smurf@ubuntu-linux:~$ ls -l mysmurf
---------- 1 smurf developers 64 Oct 23 13...
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