permissions.md

Basic

https://en.wikipedia.org/wiki/File_system_permissions

Folder attributes

https://unix.stackexchange.com/questions/21251/execute-vs-read-bit-how-do-directory-permissions-in-linux-work

Sticky bit

TODO

SUID & SGID

https://www.thegeekdiary.com/what-is-suid-sgid-and-sticky-bit/

Notation

To represent the setuid, setgid and sticky or text attributes, the executable character ('x' or '-') is modified. Though these attributes affect the overall file, not only users in one class, the setuid attribute modifies the executable character in the triad for the user, the setgid attribute modifies the executable character in the triad for the group and the sticky or text attribute modifies the executable character in the triad for others. For the setuid or setgid attributes, in the first or second triad, the 'x' becomes 's' and the '-' becomes 'S'. For the sticky or text attribute, in the third triad, the 'x' becomes 't' and the '-' becomes 'T'. Here is an example:

• -rwsr-Sr-t: a file whose user class has read, write and execute permissions; whose group class has read permission; whose others class has read and execute permissions; and which has setuid, setgid and sticky attributes set.

ACL

https://www.geeksforgeeks.org/access-control-listsacl-linux/