The umask value subtracts permission bits from the system defaults (- files: 0666, directories: 0777). With umask 0036(octal): - Files get 0666 & ~0036 = 0640→ -rw-r----- - Directories get 0777 & ~0036 = 0741→ drwxr----x None of the other umask values produce both of these target permissions.