Chapter 26

:leak: /n./ With qualifier, one of a class of resource-management bugs that occur when resources are not freed properly after operations on them are finished, so they effectively disappear (leak out). This leads to eventual exhaustion as new allocation requests come in. {memory leak} and {fd leak} have their own entries; one might also refer, to, say, a `window handle leak' in a window system.

:leaky heap: /n./ [Cambridge] An {arena} with a {memory leak}.

:leapfrog attack: /n./ Use of userid and password information obtained illicitly from one host (e.g., downloading a file of account IDs and passwords, tapping TELNET, etc.) to compromise another host. Also, the act of TELNETting through one or more hosts in order to confuse a trace (a standard cracker procedure).

:leech: /n./ Among BBS types, crackers and {warez d00dz}, one who consumes knowledge without generating new software, cracks, or techniques. BBS culture specifically defines a leech as someone who downloads files with few or no uploads in return, and who does not contribute to the message section. Cracker culture extends this definition to someone (a {lamer}, usually) who constantly presses informed sources for information and/or assistance, but has nothing to contribute.

:legal: /adj./ Loosely used to mean `in accordance with all the relevant rules', esp. in connection with some set of constraints defined by software. "The older =+ alternate for += is no longer legal syntax in ANSI C." "This parser processes each line of legal input the moment it sees the trailing linefeed." Hackers often model their work as a sort of game played with the environment in which the objective is to maneuver through the thicket of `natural laws' to achieve a desired objective. Their use of `legal' is flavored as much by this game-playing sense as by the more conventional one having to do with courts and lawyers. Compare {language lawyer}, {legalese}.

:legalese: /n./ Dense, pedantic verbiage in a language description, product specification, or interface standard; text that seems designed to obfuscate and requires a {language lawyer} to {parse} it. Though hackers are not afraid of high information density and complexity in language (indeed, they rather enjoy both), they share a deep and abiding loathing for legalese; they associate it with deception, {suit}s, and situations in which hackers generally get the short end of the stick.

:LER: /L-E-R/ /n./ [TMRC, from `Light-Emitting Diode'] A light-emitting resistor (that is, one in the process of burning up). Ohm's law was broken. See also {SED}.

:LERP: /lerp/ /vi.,n./ Quasi-acronym for Linear Interpolation, used as a verb or noun for the operation. "Bresenham's algorithm lerps incrementally between the two endpoints of the line."

:let the smoke out: /v./ To fry hardware (see {fried}). See {magic smoke} for a discussion of the underlying mythology.

:letterbomb: 1. /n./ A piece of {email} containing {live data} intended to do nefarious things to the recipient's machine or terminal. It is possible, for example, to send letterbombs that will lock up some specific kinds of terminals when they are viewed, so thoroughly that the user must cycle power (see {cycle}, sense 3) to unwedge them. Under Unix, a letterbomb can also try to get part of its contents interpreted as a shell command to the mailer. The results of this could range from silly to tragic. See also {Trojan horse}; compare {nastygram}. 2. Loosely, a {mailbomb}.

:lexer: /lek'sr/ /n./ Common hacker shorthand for `lexical analyzer', the input-tokenizing stage in the parser for a language (the part that breaks it into word-like pieces). "Some C lexers get confused by the old-style compound ops like `=-'."

:lexiphage: /lek'si-fayj`/ /n./ A notorious word {chomper} on ITS. See {bagbiter}. This program would draw on a selected victim's bitmapped terminal the words "THE BAG" in ornate letters, followed a pair of jaws biting pieces of it off.

:life: /n./ 1. A cellular-automata game invented by John Horton Conway and first introduced publicly by Martin Gardner ("Scientific American", October 1970); the game's popularity had to wait a few years for computers on which it could reasonably be played, as it's no fun to simulate the cells by hand. Many hackers pass through a stage of fascination with it, and hackers at various places contributed heavily to the mathematical analysis of this game (most notably Bill Gosper at MIT, who even implemented life in {TECO}!; see {Gosperism}). When a hacker mentions `life', he is much more likely to mean this game than the magazine, the breakfast cereal, or the human state of existence. 2. The opposite of {Usenet}. As in "{Get a life!}"

:Life is hard: /prov./ [XEROX PARC] This phrase has two possible interpretations: (1) "While your suggestion may have some merit, I will behave as though I hadn't heard it." (2) "While your suggestion has obvious merit, equally obvious circumstances prevent it from being seriously considered." The charm of the phrase lies precisely in this subtle but important ambiguity.

:light pipe: /n./ Fiber optic cable. Oppose {copper}.

:lightweight: /adj./ Opposite of {heavyweight}; usually found in combining forms such as `lightweight process'.

:like kicking dead whales down the beach: /adj./ Describes a slow, difficult, and disgusting process. First popularized by a famous quote about the difficulty of getting work done under one of IBM's mainframe OSes. "Well, you *could* write a C compiler in COBOL, but it would be like kicking dead whales down the beach." See also {fear and loathing}.

:like nailing jelly to a tree: /adj./ Used to describe a task thought to be impossible, esp. one in which the difficulty arises from poor specification or inherent slipperiness in the problem domain. "Trying to display the `prettiest' arrangement of nodes and arcs that diagrams a given graph is like nailing jelly to a tree, because nobody's sure what `prettiest' means algorithmically."

Hacker use of this term may recall mainstream slang originated early in the 20th century by President Theodore Roosevelt. There is a legend that, weary of inconclusive talks with Colombia over the right to dig a canal through its then-province Panama, he remarked, "Negotiating with those pirates is like trying to nail currant jelly to the wall." Roosevelt's government subsequently encouraged the anti-Colombian insurgency that created the nation of Panama.

:line 666: [from Christian eschatological myth] /n./ The notional line of source at which a program fails for obscure reasons, implying either that *somebody* is out to get it (when you are the programmer), or that it richly deserves to be so gotten (when you are not). "It works when I trace through it, but seems to crash on line 666 when I run it." "What happens is that whenever a large batch comes through, mmdf dies on the Line of the Beast. Probably some twit hardcoded a buffer size."

:line eater, the: /n. obs./ [Usenet] 1. A bug in some now-obsolete versions of the netnews software that used to eat up to BUFSIZ bytes of the article text. The bug was triggered by having the text of the article start with a space or tab. This bug was quickly personified as a mythical creature called the `line eater', and postings often included a dummy line of `line eater food'. Ironically, line eater `food' not beginning with a space or tab wasn't actually eaten, since the bug was avoided; but if there *was* a space or tab before it, then the line eater would eat the food *and* the beginning of the text it was supposed to be protecting. The practice of `sacrificing to the line eater' continued for some time after the bug had been {nailed to the wall}, and is still humorously referred to. The bug itself was still occasionally reported to be lurking in some mail-to-netnews gateways as late as 1991. 2. See {NSA line eater}.

:line noise: /n./ 1. [techspeak] Spurious characters due to electrical noise in a communications link, especially an RS-232 serial connection. Line noise may be induced by poor connections, interference or crosstalk from other circuits, electrical storms, {cosmic rays}, or (notionally) birds crapping on the phone wires. 2. Any chunk of data in a file or elsewhere that looks like the results of line noise in sense 1. 3. Text that is theoretically a readable text or program source but employs syntax so bizarre that it looks like line noise in senses 1 or 2. Yes, there are languages this ugly. The canonical example is {TECO}; it is often claimed that "TECO's input syntax is indistinguishable from line noise." Other non-{WYSIWYG} editors, such as Multics `qed' and Unix `ed', in the hands of a real hacker, also qualify easily, as do deliberately obfuscated languages such as {INTERCAL}.

:line starve: [MIT] 1. /vi./ To feed paper through a printer the wrong way by one line (most printers can't do this). On a display terminal, to move the cursor up to the previous line of the screen. "To print `X squared', you just output `X', line starve, `2', line feed." (The line starve causes the `2' to appear on the line above the `X', and the line feed gets back to the original line.) 2. /n./ A character (or character sequence) that causes a terminal to perform this action. ASCII 0011010, also called SUB or control-Z, was one common line-starve character in the days before microcomputers and the X3.64 terminal standard. Unlike `line feed', `line starve' is *not* standard {{ASCII}} terminology. Even among hackers it is considered a bit silly. 3. [proposed] A sequence such as \c (used in System V echo, as well as {{nroff}} and {{troff}}) that suppresses a {newline} or other character(s) that would normally be emitted.

:linearithmic: /adj./ Of an algorithm, having running time that is O(N log N). Coined as a portmanteau of `linear' and `logarithmic' in "Algorithms In C" by Robert Sedgewick (Addison-Wesley 1990, ISBN 0-201-51425-7).

:link farm: /n./ [Unix] A directory tree that contains many links to files in a master directory tree of files. Link farms save space when one is maintaining several nearly identical copies of the same source tree -- for example, when the only difference is architecture-dependent object files. "Let's freeze the source and then rebuild the FROBOZZ-3 and FROBOZZ-4 link farms." Link farms may also be used to get around restrictions on the number of `-I' (include-file directory) arguments on older C preprocessors. However, they can also get completely out of hand, becoming the filesystem equivalent of {spaghetti code}.

:link-dead: /adj./ [MUD] Said of a {MUD} character who has frozen in place because of a dropped Internet connection.

:lint: [from Unix's `lint(1)', named for the bits of fluff it supposedly picks from programs] 1. /vt./ To examine a program closely for style, language usage, and portability problems, esp. if in C, esp. if via use of automated analysis tools, most esp. if the Unix utility `lint(1)' is used. This term used to be restricted to use of `lint(1)' itself, but (judging by references on Usenet) it has become a shorthand for {desk check} at some non-Unix shops, even in languages other than C. Also as /v./ {delint}. 2. /n./ Excess verbiage in a document, as in "This draft has too much lint".

:Linux:: /lee'nuhks/ or /li'nuks/, *not* /li:'nuhks/ /n./ The free Unix workalike created by Linus Torvalds and friends starting about 1990 (the pronunciation /lee'nuhks/ is preferred because the name `Linus' has an /ee/ sound in Swedish). This may be the most remarkable hacker project in history -- an entire clone of Unix for 386, 486 and Pentium micros, distributed for free with sources over the net (ports to Alpha and Sparc-based machines are underway). This is what {GNU} aimed to be, but the Free Software Foundation has not (as of early 1996) produced the kernel to go with its Unix toolset (which Linux uses). Other, similar efforts like FreeBSD and NetBSD have been much less successful. The secret of Linux's success seems to be that Linus worked much harder early on to keep the development process open and recruit other hackers, creating a snowball effect.

:lion food: /n./ [IBM] Middle management or HQ staff (or, by extension, administrative drones in general). From an old joke about two lions who, escaping from the zoo, split up to increase their chances but agree to meet after 2 months. When they finally meet, one is skinny and the other overweight. The thin one says: "How did you manage? I ate a human just once and they turned out a small army to chase me -- guns, nets, it was terrible. Since then I've been reduced to eating mice, insects, even grass." The fat one replies: "Well, *I* hid near an IBM office and ate a manager a day. And nobody even noticed!"

:Lions Book: /n./ "Source Code and Commentary on Unix level 6", by John Lions. The two parts of this book contained (1) the entire source listing of the Unix Version 6 kernel, and (2) a commentary on the source discussing the algorithms. These were circulated internally at the University of New South Wales beginning 1976--77, and were, for years after, the *only* detailed kernel documentation available to anyone outside Bell Labs. Because Western Electric wished to maintain trade secret status on the kernel, the Lions Book was only supposed to be distributed to affiliates of source licensees. In spite of this, it soon spread by samizdat to a good many of the early Unix hackers.

[1996 update: The Lions book lives again! It will finally see legal public print as ISBN 1-57398-013-7 from Peer-To-Peer Communications, with a forward by Dennis Ritchie.]

:LISP: /n./ [from `LISt Processing language', but mythically from `Lots of Irritating Superfluous Parentheses'] AI's mother tongue, a language based on the ideas of (a) variable-length lists and trees as fundamental data types, and (b) the interpretation of code as data and vice-versa. Invented by John McCarthy at MIT in the late 1950s, it is actually older than any other {HLL} still in use except FORTRAN. Accordingly, it has undergone considerable adaptive radiation over the years; modern variants are quite different in detail from the original LISP 1.5. The dominant HLL among hackers until the early 1980s, LISP now shares the throne with {C}. See {languages of choice}.

All LISP functions and programs are expressions that return values; this, together with the high memory utilization of LISPs, gave rise to Alan Perlis's famous quip (itself a take on an Oscar Wilde quote) that "LISP programmers know the value of everything and the cost of nothing".

One significant application for LISP has been as a proof by example that most newer languages, such as {COBOL} and {Ada}, are full of unnecessary {crock}s. When the {Right Thing} has already been done once, there is no justification for {bogosity} in newer languages.

:list-bomb: /v./ To {mailbomb} someone by forging messages causing the victim to become a subscriber to many mailing lists. This is a self-defeating tactic; it merely forces mailing list servers to require confirmation by return message for every subscription.

:literature, the: /n./ Computer-science journals and other publications, vaguely gestured at to answer a question that the speaker believes is {trivial}. Thus, one might answer an annoying question by saying "It's in the literature." Oppose {Knuth}, which has no connotation of triviality.

:lithium lick: /n./ [NeXT] Steve Jobs. Employees who have gotten too much attention from their esteemed founder are said to have `lithium lick' when they begin to show signs of Jobsian fervor and repeat the most recent catch phrases in normal conversation --- for example, "It just works, right out of the box!"

:little-endian: /adj./ Describes a computer architecture in which, within a given 16- or 32-bit word, bytes at lower addresses have lower significance (the word is stored `little-end-first'). The PDP-11 and VAX families of computers and Intel microprocessors and a lot of communications and networking hardware are little-endian. See {big-endian}, {middle-endian}, {NUXI problem}. The term is sometimes used to describe the ordering of units other than bytes; most often, bits within a byte.

:live: /li:v/ /adj.,adv./ Opposite of `test'. Refers to actual real-world data or a program working with it. For example, the response to "I think the record deleter is finished" might be "Is it live yet?" or "Have you tried it out on live data?" This usage usually carries the connotation that live data is more fragile and must not be corrupted, or bad things will happen. So a more appropriate response might be: "Well, make sure it works perfectly before we throw live data at it." The implication here is that record deletion is something pretty significant, and a haywire record-deleter running amok live would probably cause great harm.

:live data: /n./ 1. Data that is written to be interpreted and takes over program flow when triggered by some un-obvious operation, such as viewing it. One use of such hacks is to break security. For example, some smart terminals have commands that allow one to download strings to program keys; this can be used to write live data that, when listed to the terminal, infects it with a security-breaking {virus} that is triggered the next time a hapless user strikes that key. For another, there are some well-known bugs in {vi} that allow certain texts to send arbitrary commands back to the machine when they are simply viewed. 2. In C code, data that includes pointers to function {hook}s (executable code). 3. An object, such as a {trampoline}, that is constructed on the fly by a program and intended to be executed as code.

:Live Free Or Die!: /imp./ 1. The state motto of New Hampshire, which appears on that state's automobile license plates. 2. A slogan associated with Unix in the romantic days when Unix aficionados saw themselves as a tiny, beleaguered underground tilting against the windmills of industry. The "free" referred specifically to freedom from the {fascist} design philosophies and crufty misfeatures common on commercial operating systems. Armando Stettner, one of the early Unix developers, used to give out fake license plates bearing this motto under a large Unix, all in New Hampshire colors of green and white. These are now valued collector's items. Recently (1994) an inferior imitation of these has been put in circulation with a red corporate logo added.

:livelock: /li:v'lok/ /n./ A situation in which some critical stage of a task is unable to finish because its clients perpetually create more work for it to do after they have been serviced but before it can clear its queue. Differs from {deadlock} in that the process is not blocked or waiting for anything, but has a virtually infinite amount of work to do and can never catch up.

:liveware: /li:v'weir/ /n./ 1. Synonym for {wetware}. Less common. 2. [Cambridge] Vermin. "Waiter, there's some liveware in my salad..."

:lobotomy: /n./ 1. What a hacker subjected to formal management training is said to have undergone. At IBM and elsewhere this term is used by both hackers and low-level management; the latter doubtless intend it as a joke. 2. The act of removing the processor from a microcomputer in order to replace or upgrade it. Some very cheap {clone} systems are sold in `lobotomized' form -- everything but the brain.

:locals, the: /pl.n./ The users on one's local network (as opposed, say, to people one reaches via public Internet or UUCP connects). The marked thing about this usage is how little it has to do with real-space distance. "I have to do some tweaking on this mail utility before releasing it to the locals."

:locked and loaded: /adj./ [from military slang for an M-16 rifle with magazine inserted and prepared for firing] Said of a removable disk volume properly prepared for use -- that is, locked into the drive and with the heads loaded. Ironically, because their heads are `loaded' whenever the power is up, this description is never used of {{Winchester}} drives (which are named after a rifle).

:locked up: /adj./ Syn. for {hung}, {wedged}.

:logic bomb: /n./ Code surreptitiously inserted into an application or OS that causes it to perform some destructive or security-compromising activity whenever specified conditions are met. Compare {back door}.

:logical: /adj./ [from the technical term `logical device', wherein a physical device is referred to by an arbitrary `logical' name] Having the role of. If a person (say, Les Earnest at SAIL) who had long held a certain post left and were replaced, the replacement would for a while be known as the `logical' Les Earnest. (This does not imply any judgment on the replacement.) Compare {virtual}.

At Stanford, `logical' compass directions denote a coordinate system in which `logical north' is toward San Francisco, `logical west' is toward the ocean, etc., even though logical north varies between physical (true) north near San Francisco and physical west near San Jose. (The best rule of thumb here is that, by definition, El Camino Real always runs logical north-and-south.) In giving directions, one might say: "To get to Rincon Tarasco restaurant, get onto {El Camino Bignum} going logical north." Using the word `logical' helps to prevent the recipient from worrying about that the fact that the sun is setting almost directly in front of him. The concept is reinforced by North American highways which are almost, but not quite, consistently labeled with logical rather than physical directions. A similar situation exists at MIT: Route 128 (famous for the electronics industry that has grown up along it) is a 3-quarters circle surrounding Boston at a radius of 10 miles, terminating near the coastline at each end. It would be most precise to describe the two directions along this highway as `clockwise' and `counterclockwise', but the road signs all say "north" and "south", respectively. A hacker might describe these directions as `logical north' and `logical south', to indicate that they are conventional directions not corresponding to the usual denotation for those words. (If you went logical south along the entire length of route 128, you would start out going northwest, curve around to the south, and finish headed due east, passing along one infamous stretch of pavement that is simultaneously route 128 south and Interstate 93 north, and is signed as such!)

:loop through: /vt./ To process each element of a list of things. "Hold on, I've got to loop through my paper mail." Derives from the computer-language notion of an iterative loop; compare `cdr down' (under {cdr}), which is less common among C and Unix programmers. ITS hackers used to say `IRP over' after an obscure pseudo-op in the MIDAS PDP-10 assembler (the same IRP op can nowadays be found in Microsoft's assembler).