patch

patch  1. n. A temporary addition to a piece of code,
   usually as a {quick-and-dirty} remedy to an existing bug or
   misfeature.  A patch may or may not work, and may or may not
   eventually be incorporated permanently into the program.
   Distinguished from a {diff} or {mod} by the fact that a patch
   is generated by more primitive means than the rest of the program;
   the classical examples are instructions modified by using the front
   panel switches, and changes made directly to the binary executable
   of a program originally written in an {HLL}.  Compare
   {one-line fix}.  2. vt. To insert a patch into a piece of code.
   3. [in the UNIX world] n. A {diff} (sense 2).  4. A set of
   modifications to binaries to be applied by a patching program.  IBM
   operating systems often receive updates to the operating system in
   the form of absolute hexadecimal patches.  If you have modified
   your OS, you have to disassemble these back to the source.  The
   patches might later be corrected by other patches on top of them
   (patches were said to "grow scar tissue").  The result was often
   a convoluted {patch space} and headaches galore.  5. [UNIX] the
   `patch(1)' program, written by Larry Wall, which automatically
   applies a patch (sense 3) to a set of source code.

   There is a classic story of a {tiger team} penetrating a secure
   military computer that illustrates the danger inherent in binary
   patches (or, indeed, any patches that you can't -- or don't ---
   inspect and examine before installing).  They couldn't find any
   {trap door}s or any way to penetrate security of IBM's OS, so
   they made a site visit to an IBM office (remember, these were
   official military types who were purportedly on official business),
   swiped some IBM stationery, and created a fake patch.  The patch
   was actually the trapdoor they needed.  The patch was distributed
   at about the right time for an IBM patch, had official stationery
   and all accompanying documentation, and was dutifully installed.
   The installation manager very shortly thereafter learned something
   about proper procedures.