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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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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

Primary versus secondary groups

Every user in Linux must be a member of a primary group. Primary groups are also referred to as login groups. By default, whenever a new user is created, a group is also created with the same name as the user, and this group becomes the primary group of the new user.

On the other hand, a user may or may not be a member of a secondary group. Secondary groups are also sometimes referred to as supplementary groups. You can think of a secondary group as any group that a user is a member of aside from the user's primary group.

Do not worry if you don't understand the concept of primary and secondary groups just yet; it will become crystal clear by the end of this chapter.

Let's create a new user named dummy:

root@ubuntu-linux:~# useradd -m dummy

Now, if you look at the last line of the /etc/group file, you will see that a group named dummy is also created:

root@ubuntu-linux:~# tail -n 1 /etc/group 
dummy:x:1004:

This dummy group is the primary...

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