Understanding Permissions

Linux is a multi-user operating system. This means that many people can use the system at once, but they shouldn't necessarily be able to see or modify each other's files.

The 3 Permissions

• r (Read): You can view the contents of the file.
• w (Write): You can modify or delete the file.
• x (Execute): You can run the file as a program or script.

The 3 Categories of Users

• User (Owner): The person who created the file.
• Group: A collection of users who share access to the file.
• Others (World): Everyone else on the system.

Reading the Permissions Output

When you run ls -l, the first 10 characters tell you about the permissions:

Example: -rwxr-xr-- 1. The first character indicates the type (- is a file, d is a directory).
2. The next 3 characters are for the Owner (rwx).
3. The next 3 characters are for the Group (r-x).
4. The last 3 characters are for Others (r--).

The Table of Permissions