gistfile1.txt

MODES
     Modes may be absolute or symbolic.  An absolute mode is an octal number constructed from the sum of one
     or more of the following values:

           4000    (the set-user-ID-on-execution bit) Executable files with this bit set will run with
                   effective uid set to the uid of the file owner.  Directories with the set-user-id bit set
                   will force all files and sub-directories created in them to be owned by the directory
                   owner and not by the uid of the creating process, if the underlying file system supports
                   this feature: see chmod(2) and the suiddir option to mount(8).
           2000    (the set-group-ID-on-execution bit) Executable files with this bit set will run with
                   effective gid set to the gid of the file owner.
           1000    (the sticky bit) See chmod(2) and sticky(8).
           0400    Allow read by owner.
           0200    Allow write by owner.
           0100    For files, allow execution by owner.  For directories, allow the owner to search in the
                   directory.
           0040    Allow read by group members.
           0020    Allow write by group members.
           0010    For files, allow execution by group members.  For directories, allow group members to
                   search in the directory.
           0004    Allow read by others.
           0002    Allow write by others.
           0001    For files, allow execution by others.  For directories allow others to search in the
                   directory.

     For example, the absolute mode that permits read, write and execute by the owner, read and execute by
     group members, read and execute by others, and no set-uid or set-gid behaviour is 755
     (400+200+100+040+010+004+001).