This is best explained by way of an example. Suppose the file data contains the lines:
xcol y z v u w i ---- - - - - - - 0 1 2 3 4 * 6 1 2 3 4 5 ** 7 2 3 4 5 6 *** 8 3 4 5 6 7 v 9 4 5 6 7 8 vi 10where exactly one tab-character separates the columns.
The command deal y v xcol < data yields
y v xcol - - ---- 1 3 0 1 2 3 2 3 4 3 4 5 4 5 6on the standard output.
deal is typically used with other reldb commands such as select, in which case the output from one command is piped into another.