bread crumbs

Debugging statements inserted into a program that emit output

or log indicators of the program's state to a file so you

can see where it dies or pin down the cause of surprising

behaviour. The term is probably a reference to the Hansel and

Gretel story from the Brothers Grimm; in several variants, a

character leaves a trail of bread crumbs so as not to get lost

in the woods.

[Jargon File]