Octal Numbers in Linux Filesystem Permissions

• octal numbers - 0-7

• adding up 4, 2 or 1 (always a unique combination)

• set user ID (setuid) - 4

• set group ID (setgid) - 2

• sticky - 1

• owner user read - 4

• owner user write - 2

• owner user execute - 1

• users in group read - 4

• users in group write - 2

• users in group execute - 1

• other users read - 4

• other users write - 2

• other users execute - 1