"Hackers inside", Unix
1. Something passed between routines or programs that enables the receiver to perform some operation; a capability ticket or opaque identifier. Especially used of
small data objects that contain data encoded in a strange or intrinsically machine-dependent way. E.g., on
non-Unix OSes with a non-byte-stream model of files, the result of ftell(3)
may be a
magic cookie rather than a byte offset; it can be passed to fseek(3), but not operated on in any meaningful way. The phrase `it hands you a
magic cookie' means it returns a result whose contents are not defined but which can be passed back to the same or some other program later.
2. An in-band code for changing graphic rendition (e.g., inverse video or underlining) or performing other control functions (see also cookie). Some older terminals would leave a
blank on the screen corresponding to mode-change magic
cookies; this was also called a glitch (or occasionally a `turd'; compare mouse droppings). S