chmod: Understanding Unix File Permissions
Unix permissions determine who can do what with files and directories. Understanding them is fundamental to system security and avoiding “Permission denied” errors. The Permission Model Every file has three permission types for three user classes: Permission Types: r (read) = 4 w (write) = 2 x (execute) = 1 User Classes: u (user/owner) g (group) o (others) Reading Permissions 1 2 ls -l file.txt # -rw-r--r-- 1 user group 1234 Feb 25 12:00 file.txt Breaking down -rw-r--r--: ...