Options
-c Separator character used in left-side
-t Separator character used in right-side
-j Column for output from left-side (default: entire row minus key)
Column defined by j will ALWAYS search against column 0 of right-side
-w Number of columns on the right-side (default 2)
-k Column for output from right-side (default: entire row)
-k 0 Pairs the match with first column of right-side
-k 1 Pairs the match with second column of right-side
-s Search column from left-side (default: column 0)
-i Case-insensitive key matching
-t num-threads