Rack: noun Assembly of parallel bars, leaning against the wall (of a barn, a stable, a sheepfold) which is used to receive fodder for cattle.
Denture.
Eat at all the racks: be opportunistic; putting his material interest before his ideas, pleasing everyone out of interest (see the origin of the expression below).
Eat at two racks; eat at the two racks: to be paid by opposing and contradictory interests.
The rack is empty: nothing to eat.
To have the teeth in the rack: to be hungry, not to eat enough.
The expression "Eat at all the racks": Take advantage of all possible situations, without scruples - Draw without hesitation in everything that can be beneficial.