The Hacker's Dictionary, - [best reads of all time .txt] 📗

around until something happens. "The program displays a menu and then hangs until you type a character." Compare {block}. To attach a peripheral device, esp. in the construction `hang off': "We're going to hang another tape drive off the file server." Implies a device attached with cables, rather than something that is strictly inside the machine's chassis.

:Hanlon's Razor: prov. A corollary of {Finagle's Law}, similar to Occam's Razor, that reads "Never attribute to malice that which can be adequately explained by stupidity." The derivation of the common title Hanlon's Razor is unknown; a similar epigram has been attributed to William James. Quoted here because it seems to be a particular favorite of hackers, often showing up in {fortune cookie} files and the login banners of BBS systems and commercial networks. This probably reflects the hacker's daily experience of environments created by well-intentioned but short-sighted people.

:happily: adv. Of software, used to emphasize that a program is unaware of some important fact about its environment, either because it has been fooled into believing a lie, or because it doesn't care. The sense of `happy' here is not that of elation, but rather that of blissful ignorance. "The program continues to run, happily unaware that its output is going to /dev/null."

:haque: /hak/ [USENET] n. Variant spelling of {hack}, used only for the noun form and connoting an {elegant} hack.

:hard boot: n. See {boot}.

:hardcoded: adj. 1. Said of data inserted directly into a program, where it cannot be easily modified, as opposed to data in some {profile}, resource (see {de-rezz} sense 2), or environment variable that a {user} or hacker can easily modify. 2. In C, this is esp. applied to use of a literal instead of a `#define' macro (see {magic number}).

:hardwarily: /hard-weir'-lee/ adv. In a way pertaining to hardware. "The system is hardwarily unreliable." The adjective `hardwary' is not* traditionally used, though it has recently been reported from the U.K. See {softwarily}.

:hardwired: adj. 1. In software, syn. for {hardcoded}. 2. By extension, anything that is not modifiable, especially in the sense of customizable to one's particular needs or tastes.

:has the X nature: [seems to derive from Zen Buddhist koans of the form "Does an X have the Buddha-nature?"] adj. Common hacker construction for `is an X', used for humorous emphasis. "Anyone who can't even use a program with on-screen help embedded in it truly has the {loser} nature!" See also {the X that can be Y

is not the true X}.

:hash bucket: n. A notional receptacle into which more than one thing accessed by the same key or short code might be dropped.

When you look up a name in the phone book (for example), you typically hash it by extracting its first letter; the hash buckets are the alphabetically ordered letter sections. This is used as techspeak with respect to code that uses actual hash functions; in jargon, it is used for human associative memory as well. Thus, two things `in the same hash bucket' may be confused with each other.

"If you hash English words only by length, you get too many common grammar words in the first couple of hash buckets." Compare {hash collision}.

:hash collision: [from the technical usage] n. (var. `hash clash') When used of people, signifies a confusion in associative memory or imagination, especially a persistent one (see {thinko}). True story: One of us [ESR] was once on the phone with a friend about to move out to Berkeley. When asked what he expected Berkeley to be like, the friend replied: "Well, I have this mental picture of naked women throwing Molotov cocktails, but I think that's just a collision in my hash tables." Compare {hash bucket}.

:hat: n. Common (spoken) name for the circumflex (`^', ASCII 1011110) character. See {ASCII} for other synonyms.

:HCF: /H-C-F/ n. Mnemonic for `Halt and Catch Fire', any of several undocumented and semi-mythical machine instructions with destructive side-effects, supposedly included for test purposes on several well-known architectures going as far back as the IBM 360.

The MC6800 microprocessor was the first for which an HCF opcode became widely known. This instruction caused the processor to {toggle} a subset of the bus lines as rapidly as it could; in some configurations this could actually cause lines to burn up.

:heads down: [Sun] adj. Concentrating, usually so heavily and for so long that everything outside the focus area is missed. See also {hack mode} and {larval stage}, although it is not confined to fledgling hackers.

:heartbeat: n. 1. The signal emitted by a Level 2 Ethernet transceiver at the end of every packet to show that the collision-detection circuit is still connected. 2. A periodic synchronization signal used by software or hardware, such as a bus clock or a periodic interrupt. 3. The `natural' oscillation frequency of a computer's clock crystal, before frequency division down to the machine's clock rate. 4. A signal emitted at regular intervals by software to demonstrate that it is still alive.

Sometimes hardware is designed to reboot the machine if it stops hearing a heartbeat. See also {breath-of-life packet}.

:heatseeker: [IBM] n. A customer who can be relied upon to always buy the latest version of an existing product (not quite the same as a member the {lunatic fringe}). A 1992 example of a heatseeker is someone who, owning a 286 PC and Windows 3.0, goes out and buys Windows 3.1 (which offers no worthwhile benefits unless you have a 386). If all customers were heatseekers, vast amounts of money could be made by just fixing the bugs in each release (n) and selling it to them as release (n+1).

:heavy metal: [Cambridge] n. Syn. {big iron}.

:heavy wizardry: n. Code or designs that trade on a particularly intimate knowledge or experience of a particular operating system or language or complex application interface. Distinguished from {deep magic}, which trades more on arcane theoretical

knowledge. Writing device drivers is heavy wizardry; so is interfacing to {X} (sense 2) without a toolkit. Esp. found in comments similar to "Heavy wizardry begins here ...". Compare {voodoo programming}.

:heavyweight: adj. High-overhead; {baroque}; code-intensive; featureful, but costly. Esp. used of communication protocols, language designs, and any sort of implementation in which maximum generality and/or ease of implementation has been pushed at the expense of mundane considerations such as speed, memory utilization, and startup time. {EMACS} is a heavyweight editor; {X} is an extremely heavyweight window system. This term isn't pejorative, but one man's heavyweight is another's {elephantine} and a third's {monstrosity}. Oppose lightweight'. Usage: now borders on techspeak, especially in the compoundheavyweight process'.

:heisenbug: /hi:'zen-buhg/ [from Heisenberg's Uncertainty Principle in quantum physics] n. A bug that disappears or alters its behavior when one attempts to probe or isolate it. Antonym of {Bohr bug}; see also {mandelbug}, {schroedinbug}. In C, nine out of ten heisenbugs result from either {fandango on core}

phenomena (esp. lossage related to corruption of the malloc {arena}) or errors that {smash the stack}.

:Helen Keller mode: n. 1. State of a hardware or software system that is deaf, dumb, and blind, i.e., accepting no input and generating no output, usually due to an infinite loop or some other excursion into {deep space}. (Unfair to the real Helen Keller, whose success at learning speech was triumphant.) See also {go flatline}, {catatonic}. 2. On IBM PCs under DOS, refers to a specific failure mode in which a screen saver has kicked in over an {ill-behaved} application which bypasses the interrupts the screen saver watches for activity. Your choices are to try to get from the program's current state through a successful save-and-exit without being able to see what you're doing, or re-boot the machine. This isn't (strictly speaking) a crash.

:hello, sailor!: interj. Occasional West Coast equivalent of {hello, world}; seems to have originated at SAIL, later associated with the game {Zork} (which also included "hello, aviator" and "hello, implementor"). Originally from the traditional hooker's greeting to a swabbie fresh off the boat, of course.

:hello, wall!: excl. See {wall}.

:hello, world: interj. 1. The canonical minimal test message in the C/UNIX universe. 2. Any of the minimal programs that emit this message. Traditionally, the first program a C coder is supposed to write in a new environment is one that just prints "hello, world"

to standard output (and indeed it is the first example program in {K&R}). Environments that generate an unreasonably large executable for this trivial test or which require a {hairy}

compiler-linker invocation to generate it are considered to {lose} (see {X}). 3. Greeting uttered by a hacker making an entrance or requesting information from anyone present. "Hello, world! Is the {VAX} back up yet?"

:hex: n. 1. Short for {{hexadecimal}}, base 16. 2. A 6-pack of anything (compare {quad}, sense 2). Neither usage has anything to do with {magic} or {black art}, though the pun is appreciated and occasionally used by hackers. True story: As a joke, some hackers once offered some surplus ICs for sale to be worn as protective amulets against hostile magic. The chips were, of course, hex inverters.

:hexadecimal:: n. Base 16. Coined in the early 1960s to replace earlier `sexadecimal', which was too racy and amusing for stuffy IBM, and later adopted by the rest of the industry.

Actually, neither term is etymologically pure. If we take