list directory contents

-l     (The  letter  ell.) Do not follow symbolic links named as operands unless the -H or -L options are
       specified. Write out in long format (see the STDOUT section). When -l (ell) is specified, -1 (one)
       shall be assumed.

-t     Sort with the primary key being time modified (most recently modified first) and the secondary key
       being filename in the collating sequence.

-r     Reverse the order of the sort to get reverse collating sequence or oldest first.