Linux Permissions Guide for Beginners

In Linux, permissions are the backbone of system security. They control who can access, modify, or execute files and directories. Whether you’re a beginner, developer, or sysadmin, understanding permissions helps you keep your system safe and well-organized.

What Are Linux Permissions? ​

Every file and directory in Linux has a set of permissions that determine:

• Who can read its content
• Who can modify or delete it
• Who can execute it (run scripts or binaries)

These permissions ensure that only the right people can interact with specific files - a must for maintaining system integrity and privacy.

The Three Permission Types ​

In Linux, there are three main types of users involved in file permissions:

• Owner (User) - The person who created the file or directory. They have full control and can change its permissions.
• Group - A set of users who share similar access rights. Perfect for teamwork or shared projects.
• Others - Everyone else on the system who isn’t the owner or in the group.

Each user type can have its own read (r), write (w), and execute (x) permissions.

Permission Basics: r, w, and x ​

Symbol​	Meaning​	Description​
r​	Read​	View file content or list directory contents​
w​	Write​	Modify or delete files, or add files in a directory​
x​	Execute​	Run scripts or programs, or access directories​

Example: drwxr-xr--

Let’s break it down

• d → It’s a directory.
• rwx → The owner can read, write, and execute.
• r-x → The group can read and execute, but not write.
• r-- → Others can only read.

So, drwxr-xr-- means the owner has full control, the group can view and enter, and others can only read.

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Changing Permissions with chmod ​

You can easily change permissions using the chmod command.

Example 1 – Symbolic mode:​

chmod u+x script.sh

This gives the user (u) execute permission on script.sh.

Example 2 – Numeric mode:​

chmod 755 script.sh

Here’s how numeric permissions work:

• 7 = rwx (read + write + execute)
• 5 = r-x (read + execute)
• 0 = --- (no access)

So 755 means:

• User → full control
• Group → read and execute
• Others → read and execute

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Changing Ownership with chown ​

Every file has an owner and a group. You can change them using the chown command:

sudo chown john:developers project.txt

This assigns john as the owner and developers as the group for project.txt.

Pro tip : Always double-check ownership before changing system files!

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Why Permissions Matter ​

Correct permissions protect your system from:

• Unauthorized access
• Accidental file deletion
• Malicious script execution

In multi-user systems, managing permissions ensures collaboration without compromising security.

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Quick Reference Table ​

Task	Command Example
View file permissions	ls -l
Change permissions	chmod 644 file.txt
Add execute permission	chmod +x run.sh
Change file owner	sudo chown user file.txt
Change group	sudo chown :group file.txt

Conclusion ​

Mastering Linux permissions is one of the most valuable skills for any Linux user. It keeps your data safe, your system stable, and your workflow smooth.

Think of permissions as your system’s security gate - when managed properly, they protect everything that matters. So go ahead, explore chmod, chown, and take full control of your Linux world.