Actually it's not that complicated
Linux File Permissions in 5 Minutes | MUST KNOW!
I have been taking a course on Linux for the past few months and one aspect of Linux that always confused me was how permissions worked. For example, once I uploaded a file to my web server and got an error, my web host told me to change the file permissions to 755.
I had no idea what that meant, even though changing the permissions solved the problem. I have now discovered that Linux permissions are not that complicated, you just have to understand the system. In this article I will talk about Linux permissions at a high level and show you how to use the chmod command to change permissions on files and folders.
In Linux, there are basically three permissions that you normally have to worry about: read, write, and execute. These three are all pretty self-explanatory. Now, when these permissions are applied to a file, they are applied in levels.