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       Module 2: Users, Groups, and Permissions
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       1. The All-Powerful "Root" and sudo
       
       The Root user is the god-mode account. It can delete the entire operating system
       with one command. Because that's dangerous, we use sudo (SubUser DO).
       
       Command: sudo [command]
       
       Analogy: It’s like a security guard giving you a temporary master key. You 
       perform one task, then give the key back.
       
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       2. Understanding Permissions (ls -l)
       
       When you run ls -l, you see a string like this: -rwxr-xr--
       
       This string is broken into three sets of three:
       
       User (Owner): What the person who owns the file can do.
       Group: What members of the file's assigned group can do.
       Others: What everyone else on the system can do.
       
       The Letters:
       
       r (Read): Can view the file.
       w (Write): Can edit/delete the file.
       x (Execute): Can run the file (like a program or script).
       
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       3. Changing Permissions (chmod)
       
       You change permissions using the chmod command. The easiest way is using
       numbers:
       
       4 = Read
       2 = Write
       1 = Execute
       
       You add them together to get the permission level.
       
       7 (4+2+1) = Full access (rwx)
       5 (4+0+1) = Read & Execute (r-x)
       6 (4+2+0) = Read & Write (rw-)
       
       Example: chmod 755 myfile.txt (Owner gets 7, Group gets 5, Others get 5).
       
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       4. Managing Users
       
       sudo useradd [name]: Creates a new user.
       sudo passwd [name]: Sets the password for that user.
       sudo chown [user]:[group] [file]: Changes who owns the file.
       
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       Module 2 Practical Challenge
       
       This is where you act like a real System Administrator.
       
       Create a New Identity: Create a user named app_user. Give them a password.
       The Secret Folder: Create a directory in /home called top_secret.
       Lock it Down: Change the ownership of top_secret so it belongs to app_user.
       Restrict Access: Change the permissions (chmod) so that app_user can do 
       everything (7), but nobody else on the system (group and others) can even
       see inside the folder (00).
       
       Hint: The command will look like sudo chmod 700 /home/top_secret
       
       Test It: Try to cd into that folder as your regular user. You should get
       a "Permission Denied" error. Then try sudo cd (or sudo ls) to see if the 
       "master key" works.
       
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