magic cookie

magic cookie
 n.

   [Unix; common]

   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}). See also
   {cookie}.
    

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.

   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}.

   [{Jargon File}]

   (1995-01-25)