You can use SORT FIELDS=NONE for removeing duplicates in SORT. This is the easiest way to remove duplicates in a file. Could you pls explain the requirement that you have. Based on that I can give you some more methods to do the same.
where p,m,f describes the key you want to check for duplicates on. p is the starting position, m is the length and f is the format.
I would argue that SELECT is the easiest way to remove duplicates. In addition, SELECT gives you a lot more ways to deal with duplicates than SUM FIELDS=NONE does. Besides FIRST, you can use LAST, FIRSTDUP, LASTDUP, ALLDUPS, NODUPS, HIGHER(n), LOWER(n) and EQUALS(n). SUM FIELDS=NONE only does the FIRST function.
For complete details on the SELECT operator of DFSORT's ICETOOL, see: