File Permissions and Ownership

After you’ve worked with Linux for a while, it's almost inevitable that you'll bump into a "Permission Denied" message at some point. It's Linux's polite way of keeping order – preventing you from peeping into someone else's private files or inadvertently meddling with crucial system files.

Every file and directory has a set of nine permission bits, looking something like -rwxrwxrwx. These little guys dictate who can do what – read, write, or execute a file.

Here's a breakdown:

• The first three bits apply to the owner’s permission

• The next three apply to the group assigned to the file

• The last three apply to everyone else

In this permission alphabetti-spaghetti, the r stands for read, the w stands for write, and the x stands for execute permissions. If a dash appears in place of a letter, it means that permission is turned off for that associated read, write, or execution bit.

But here’s the twist: files and directories might be different beasts, but they share the same permission bits. The only difference is how these permissions play out for each. Let’s break down what each permission lets you do:

Permission	File	Folder
READ	View what's in the file	Permits listing the directory's contents
WRITE	Change the files contents, rename it, or delete it	Allows creating, deleting, or renaming files in the directory
EXECUTE	Run the file as a program	Permits accessing the directory and its contents