Understanding Permission Symbols: r, w, x

Understanding Permission Symbols: r, w, x

Welcome to this beginner-friendly tutorial on Linux permissions!

In Linux, every file and directory has a set of permissions that define who can read, write, or execute it. These permissions are represented by the letters: r, w, and x.

What do these symbols mean?

• r (read) – Allows viewing the contents of a file or listing the contents of a directory.
• w (write) – Allows modifying a file or adding/removing files in a directory.
• x (execute) – Allows running a file (like a script), or entering a directory.

Let’s see permissions in action

We’ll use the ls -l command to list files along with their permissions.

ls -l

-rwxr-xr--  1 user user  2048 Jul  1 10:00 hello.sh

This output shows a file named hello.sh. Let’s break down the leftmost part: -rwxr-xr--

Permission breakdown

Part	Meaning
-	It's a file (d for directory, - for regular file)
rwx	User (owner) permissions: read, write, execute
r-x	Group permissions: read, execute (but not write)
r--	Others: read only

Try this example yourself

Create a file and check its default permissions:

touch myfile.txt
ls -l myfile.txt

-rw-r--r-- 1 user user 0 Jul  2 11:30 myfile.txt

This means:

• User can read and write the file
• Group can only read
• Others can only read

What about directories?

Directory permissions behave slightly differently:

• r – Can list directory contents
• w – Can create/delete files in the directory
• x – Can enter ("cd into") the directory

Let’s check a directory’s permissions:

mkdir testdir
ls -ld testdir

drwxr-xr-x 2 user user 4096 Jul  2 11:35 testdir

This means:

• User can list, write, and enter the directory
• Group and others can read and enter, but not modify

Quick tip: Use chmod to change permissions

For example, to add execute permission for everyone on a file:

chmod +x hello.sh
ls -l hello.sh

-rwxr-xr-x 1 user user 2048 Jul  2 11:40 hello.sh

Now everyone can execute the script!

Summary

Permissions are crucial to keeping your Linux system secure and organized. Knowing what r, w, and x mean will help you control access to your files and directories with confidence.

In upcoming lessons, we'll explore changing permissions using chmod, chown, and symbolic vs numeric modes. Stay tuned!