magic cookie


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magic cookie

(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 operating systems with a non-byte-stream model of files, the result of "ftell" may be a magic cookie rather than a byte offset; it can be passed to "fseek", 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.

magic cookie

(2)
An in-band code for changing graphic rendition (e.g. inverse video or underlining) or performing other control functions. 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).

See also cookie.

magic cookie

A small data file passed from one program to another and sent back without change. Typically used in Unix systems, a magic cookie may be an identification token or password that activates a function. The "magic" implies some obscure data known only to the software and not the user. The Web cookie term was coined after magic cookie. See cookie.
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