Options: -r reverse, -n numeric (by leading number of the key), -uunique by key, -f fold case, -k START[,END] sort by a field range(1-based, whole fields), -t CHAR field separator (default: runs ofblanks). Like GNU sort, ties on the key fall back to comparing the wholeline (the "last-resort" rule), and any remaining ties keep input order;strings compare by UTF-16 code units. With -u, the first line of eachequal-key group in sorted order is kept.