What Are Permissions?
Imagine you have a diary:
- Only you can read and write (private)
- Your good friend can read but cannot write (read-only)
- Strangers cannot even look (no permissions)
The permission mechanism in Linux follows a similar concept, answering three questions: Who can access this file? What can be done with this file?
Understanding the Permission “Password”
In the previous article, we explained that when you input <span>ls -l</span>, you will see a mysterious string like this:
-rwxr-xr--
Now let’s break down this password in detail: The first character: file type
<span>-</span>= regular file<span>d</span>= directory<span>l</span>= link file
The next 9 characters: grouped in threes, correspond to:
- First 3: Owner permissions (yourself)
- Middle 3: Group permissions (friends)
- Last 3: Other users permissions (strangers)
Each position’s permission is represented by three letters:
<span>r</span>= read permission<span>w</span>= write permission<span>x</span>= execute permission<span>-</span>= no permission
Practical Example Interpretation
-rwxr-xr-- 1 app developers 2025 Dec 19 12:26 my_script.sh
Translated into plain language:
- This is a regular file (
<span>-</span>) - Owner app: readable, writable, executable (
<span>rwx</span>) - Group members developers: readable, executable, but not writable (
<span>r-x</span>) - Other users: can only read, cannot write or execute (
<span>r--</span>)
Let’s Practice
Open the terminal and type:
ls -l /bin/ls
Check what permissions this basic command has? You will find it is executable for almost all users—because it is a tool meant for everyone!