-a Include directory entries whose names begin with a dot (.)
-1 Force output to be one entry per line. This is the default when output is not to a terminal
-l List in long format. (See below.) If the
output is to a terminal, a total sum for all the file sizes is output on a
line before the long listing;
-R Recursively list subdirectories encountered;
-S Sort files by size;
-r Reverse the order of the sort to get reverse lexicographical order or the
oldest entries first (or largest files last, if combined with sort by size;
-t Sort by time modified (most recently modified first) before sorting the oper-
ands by lexicographical order.