Command line ------------ Main parameter is -a : -a field-spec[:func] if not specified, func is rem field-spec: n | n-m | -m | n- | field-spec,field-spec | !field-spec where n and m are positive integers (fields are numbered from 1) func : rem | avg | min | max | sum | first | last | smaller | greatest sum, avg, min and max require numeric values parsable by strtoll().