Chapter 24

1. [common] A problem with the discrete equivalent of a boundary condition, often exhibited in programs by iterative loops. From the following problem: "If you build a fence 100 feet long with posts 10 feet apart, how many posts do you need?" (Either 9 or 11 is a better answer than the obvious 10.) For example, suppose you have a long list or array of items, and want to process items m through n; how many items are there? The obvious answer is n - m, but that is off by one; the right answer is n - m + 1. A program that used the `obvious' formula would have a fencepost error in it. See also zeroth and off-by-one error, and note that not all off-by-one errors are fencepost errors. The game of Musical Chairs involves a catastrophic off-by-one error where N people try to sit in N - 1 chairs, but it's not a fencepost error. Fencepost errors come from counting things rather than the spaces between them, or vice versa, or by neglecting to consider whether one should count one or both ends of a row. 2. [rare] An error induced by unexpected regularities in input values, which can (for instance) completely thwart a theoretically efficient binary tree or hash table implementation. (The error here involves the difference between expected and worst case behaviors of an algorithm.)

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fiber-seeking backhoe

[common among backbone ISP personnel] Any of a genus of large, disruptive machines which routinely cut critical backbone links, creating Internet outages and packet over air problems.

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FidoNet n.

A worldwide hobbyist network of personal computers which exchanges mail, discussion groups, and files. Founded in 1984 and originally consisting only of IBM PCs and compatibles, FidoNet now includes such diverse machines as Apple ][s, Ataris, Amigas, and Unix systems. For years FidoNet actually grew faster than Usenet, but the advent of cheap Internet access probably means its days are numbered. In early 1999 Fidonet has approximately 30,000 nodes, down from 38K in 1996.

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field circus n.

[a derogatory pun on `field service'] The field service organization of any hardware manufacturer, but originally DEC. There is an entire genre of jokes about field circus engineers:

Q: How can you recognize a field circus engineer with a flat tire? A: He's changing one tire at a time to see which one is flat.

Q: How can you recognize a field circus engineer who is out of gas? A: He's changing one tire at a time to see which one is flat.

Q: How can you tell it's your field circus engineer? A: The spare is flat, too.

[See Easter egging for additional insight on these jokes.]

There is also the `Field Circus Cheer' (from the old plan file for DEC on MIT-AI):

Maynard! Maynard! Don't mess with us! We're mean and we're tough! If you get us confused We'll screw up your stuff.

(DEC's service HQ, still extant under the Compaq regime, is located in Maynard, Massachusetts.)

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field servoid [play on `android'] /fee'ld ser'voyd/ n.

Representative of a field service organization (see field circus). This has many of the implications of droid.

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Fight-o-net n.

[FidoNet] Deliberate distortion of FidoNet, often applied after a flurry of flamage in a particular echo, especially the SYSOP echo or Fidonews (see 'Snooze).

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File Attach [FidoNet]

1. n. A file sent along with a mail message from one FidoNet to another. 2. vt. Sending someone a file by using the File Attach option in a FidoNet mailer.

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File Request [FidoNet]

1. n. The FidoNet equivalent of FTP, in which one FidoNet system automatically dials another and snarfs one or more files. Often abbreviated `FReq'; files are often announced as being "available for FReq" in the same way that files are announced as being "available for/by anonymous FTP" on the Internet. 2. vt. The act of getting a copy of a file by using the File Request option of the FidoNet mailer.

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file signature n.

A magic number, sense 3.

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filk /filk/ n.,v.

[from SF fandom, where a typo for `folk' was adopted as a new word] A popular or folk song with lyrics revised or completely new lyrics and/or music, intended for humorous effect when read, and/or to be sung late at night at SF conventions. There is a flourishing subgenre of these called `computer filks', written by hackers and often containing rather sophisticated technical humor. See double bucky for an example. Compare grilf, hing, pr0n, and newsfroup.

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film at 11

[MIT: in parody of TV newscasters] 1. Used in conversation to announce ordinary events, with a sarcastic implication that these events are earth-shattering. "ITS crashes; film at 11." "Bug found in scheduler; film at 11." 2. Also widely used outside MIT to indicate that additional information will be available at some future time, without the implication of anything particularly ordinary about the referenced event. For example, "The mail file server died this morning; we found garbage all over the root directory. Film at 11." would indicate that a major failure had occurred but that the people working on it have no additional information about it as yet; use of the phrase in this way suggests gently that the problem is liable to be fixed more quickly if the people doing the fixing can spend time doing the fixing rather than responding to questions, the answers to which will appear on the normal "11:00 news", if people will just be patient.

The variant "MPEGs at 11" has recently been cited (MPEG is a digital-video format.)

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filter n.

[very common; orig. Unix, now also in MS-DOS] A program that processes an input data stream into an output data stream in some well-defined way, and does no I/O to anywhere else except possibly on error conditions; one designed to be used as a stage in a `pipeline' (see plumbing). Compare sponge.

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Finagle's Law n.

The generalized or `folk' version of Murphy's Law, fully named "Finagle's Law of Dynamic Negatives" and usually rendered "Anything that can go wrong, will". One variant favored among hackers is "The perversity of the Universe tends towards a maximum" (but see also Hanlon's Razor). The label `Finagle's Law' was popularized by SF author Larry Niven in several stories depicting a frontier culture of asteroid miners; this `Belter' culture professed a religion and/or running joke involving the worship of the dread god Finagle and his mad prophet Murphy. Some technical and scientific cultures (e.g., paleontologists) know it under the name `Sod's Law'; this usage may be more common in Great Britain.

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fine adj.

[WPI] Good, but not good enough to be cuspy. The word `fine' is used elsewhere, of course, but without the implicit comparison to the higher level implied by cuspy.

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finger

[WAITS, via BSD Unix] 1. n. A program that displays information about a particular user or all users logged on the system, or a remote system. Typically shows full name, last login time, idle time, terminal line, and terminal location (where applicable). May also display a plan file left by the user (see also Hacking X for Y). 2. vt. To apply finger to a username. 3. vt. By extension, to check a human's current state by any means. "Foodp?" "T!" "OK, finger Lisa and see if she's idle." 4. Any picture (composed of ASCII characters) depicting `the finger'. Originally a humorous component of one's plan file to deter the curious fingerer (sense 2), it has entered the arsenal of some flamers.

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finger trouble n.

Mistyping, typos, or generalized keyboard incompetence (this is surprisingly common among hackers, given the amount of time they spend at keyboards). "I keep putting colons at the end of statements instead of semicolons", "Finger trouble again, eh?".

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finger-pointing syndrome n.

All-too-frequent result of bugs, esp. in new or experimental configurations. The hardware vendor points a finger at the software. The software vendor points a finger at the hardware. All the poor users get is the finger.

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finn v.

[IRC] To pull rank on somebody based on the amount of time one has spent on IRC. The term derives from the fact that IRC was originally written in Finland in 1987. There may be some influence from the `Finn' character in William Gibson's seminal cyberpunk novel "Count Zero", who at one point says to another (much younger) character "I have a pair of shoes older than you are, so shut up!"

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firebottle n.obs.

A large, primitive, power-hungry active electrical device, similar in function to a FET but constructed out of glass, metal, and vacuum. Characterized by high cost, low density, low reliability, high-temperature operation, and high power dissipation. Sometimes mistakenly called a `tube' in the U.S. or a `valve' in England; another hackish term is glassfet.

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firefighting n.

1. What sysadmins have to do to correct sudden operational problems. An opposite of hacking. "Been hacking your new newsreader?" "No, a power glitch hosed the network and I spent the whole afternoon fighting fires." 2. The act of throwing lots of manpower and late nights at a project, esp. to get it out before deadline. See also gang bang, Mongolian Hordes technique; however, the term `firefighting' connotes that the effort is going into chasing bugs rather than adding features.

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firehose syndrome n.

In mainstream folklore it is observed that trying to drink from a firehose can be a good way to rip your lips off. On computer networks, the absence or failure of flow control mechanisms can lead to situations in which the sending system sprays a massive flood of packets at an unfortunate receiving system, more than it can handle. Compare overrun, buffer overflow.

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firewall code n.

1. The code you put in a system (say, a telephone switch) to make sure that the users can't do any damage. Since users always want to be able to do everything but never want to suffer for any mistakes, the construction of a firewall is a question not only of defensive coding but also of interface presentation, so that users don't even get curious about those corners of a system where they can burn themselves. 2. Any sanity check inserted to catch a can't happen error. Wise programmers often change code to fix a bug twice: once to fix the bug, and once to insert a firewall which would have arrested the bug before it did quite as much damage.

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firewall machine n.

A dedicated gateway machine with special security precautions on it, used to service outside network connections and dial-in lines. The idea is to protect a cluster of more loosely administered machines hidden behind it from crackers. The typical firewall is an inexpensive micro-based Unix box kept clean of critical data, with a bunch of modems and public network ports on it but just one carefully watched connection back to the rest of the cluster. The special precautions may include threat monitoring, callback, and even a complete iron box keyable to particular incoming IDs or activity patterns. Syn. flytrap, Venus flytrap.

[When first coined in the mid-1980s this term was pure jargon. Now (1999) it is techspeak, and has been retained only as an example of uptake --ESR]

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fireworks mode n.

1. The mode a machine is sometimes said to be in when it is performing a crash and burn operation. 2. There is (or was) a more specific meaning of this term in the Amiga community. The word fireworks described the effects of a particularly serious crash which prevented the video pointer(s) from getting reset at the start of the vertical blank. This caused the DAC to scroll through the entire contents of CHIP (video or video+CPU) memory. Since each bit plane would scroll separately this was quite a spectacular effect.

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firmware /ferm'weir/ n.

Embedded software contained in EPROM or flash memory. It isn't quite hardware, but at least doesn't have to be loaded from a disk like regular software. Hacker usage differs from straight techspeak in that hackers don't normally apply it to stuff that you can't possibly get at, such as the program that runs a pocket calculator. Instead, it implies that the firmware could be changed, even if doing so would mean opening a box and plugging in a new chip. A computer's BIOS is the classic example, although nowadays there is firmware in disk controllers, modems, video cards and even CD-ROM drives.

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firmy /fer'mee/ n.

Syn. stiffy (a 3.5-inch floppy disk).

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fish n.

[Adelaide University, Australia] 1. Another metasyntactic variable. See foo. Derived originally from the Monty Python skit in the middle of "The Meaning of Life" entitled "Find the Fish". 2. A pun for `microfiche'. A microfiche file cabinet may be referred to as a `fish tank'.

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FISH queue n.

[acronym, by analogy with FIFO (First In, First Out)] `First In, Still Here'. A joking way of pointing out that processing of a particular sequence of events or requests has stopped dead. Also `FISH mode' and `FISHnet'; the latter may be applied to any network that is running really slowly or exhibiting extreme flakiness.

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FITNR // adj.

[Thinking Machines, Inc.] Fixed In The Next Release. A written-only notation attached to bug reports. Often wishful thinking.

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fix n.,v.

What one does when a problem has been reported too many times to be ignored.

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FIXME imp.

[common] A standard tag often put in C comments near a piece of code that needs work. The point of doing so is that a grep or a similar pattern-matching tool can find all such places quickly.

/* FIXME: note this is common in GNU code. */

Compare XXX.

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flag n.

[very common] A variable or quantity that can take on one of two values; a bit, particularly one that is used to indicate one of two outcomes or is used to control which of two things is to be done. "This flag controls whether to clear the screen before printing the message." "The program status word contains several flag bits." Used of humans analogously to bit. See also hidden flag, mode bit.

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flag day n.

A software change that is neither forward- nor backward-compatible, and which is costly to make and costly to reverse. "Can we install that without causing a flag day for all users?" This term has nothing to do with the use of the word flag to mean a variable that has two values. It came into use when a massive change was made to the Multics timesharing system to convert from the short-lived 1965 version of the ASCII code to the 1967 version (in draft at the time); this was scheduled for Flag Day (a U.S. holiday), June 14, 1966. The actual change moved the code point for the ASCII newline character; this required that all of the Multics source code, documentation, and device drivers be changed simultaneously. See also backward combatability.

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flaky adj.

(var sp. `flakey') Subject to frequent lossage. This use is of course related to the common slang use of the word to describe a person as eccentric, crazy, or just unreliable. A system that is flaky is working, sort of -- enough that you are tempted to try to use it -- but fails frequently enough that the odds in favor of finishing what you start are low. Commonwealth hackish prefers dodgy or wonky.

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flamage /flay'm*j/ n.

[very common] Flaming verbiage, esp. high-noise, low-signal postings to Usenet or other electronic fora. Often in the phrase `the usual flamage'. `Flaming' is the act itself; `flamage' the content; a `flame' is a single flaming message. See flame, also dahmum.

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flame

[at MIT, orig. from the phrase `flaming asshole'] 1. vi. To post an email message intended to insult and provoke. 2. vi. To speak incessantly and/or rabidly on some relatively uninteresting subject or with a patently ridiculous attitude. 3. vt. Either of senses 1 or 2, directed with hostility at a particular person or people. 4. n. An instance of flaming. When a discussion degenerates into useless controversy, one might tell the participants "Now you're just flaming" or "Stop all that flamage!" to try to get them to cool down (so to speak).

The term may have been independently invented at several different places. It has been reported from MIT, Carleton College and RPI (among many other places) from as far back as 1969, and from the University of Virginia in the early 1960s.

It is possible that the hackish sense of `flame' is much older than that. The poet Chaucer was also what passed for a wizard hacker in his time; he wrote a treatise on the astrolabe, the most advanced computing device of the day. In Chaucer's "Troilus and Cressida", Cressida laments her inability to grasp the proof of a particular mathematical theorem; her uncle Pandarus then observes that it's called "the fleminge of wrecches." This phrase seems to have been intended in context as "that which puts the wretches to flight" but was probably just as ambiguous in Middle English as "the flaming of wretches" would be today. One suspects that Chaucer would feel right at home on Usenet.

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flame bait n.

[common] A posting intended to trigger a flame war, or one that invites flames in reply. See also troll.

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flame on vi.,interj.

1. To begin to flame. The punning reference to Marvel Comics's Human Torch is no longer widely recognized. 2. To continue to flame. See rave, burble.

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flame war n.

[common] (var. `flamewar') An acrimonious dispute, especially when conducted on a public electronic forum such as Usenet.

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flamer n.

[common] One who habitually flames. Said esp. of obnoxious Usenet personalities.

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flap vt.

1. [obs.] To unload a DECtape (so it goes flap, flap, flap...). Old-time hackers at MIT tell of the days when the disk was device 0 and DEC microtapes were 1, 2,... and attempting to flap device 0 would instead start a motor banging inside a cabinet near the disk. 2. By extension, to unload any magnetic tape. See also macrotape. Modern cartridge tapes no longer actually flap, but the usage has remained. (The term could well be re-applied to DEC's TK50 cartridge tape drive, a spectacularly misengineered contraption which makes a loud flapping sound, almost like an old reel-type lawnmower, in one of its many tape-eating failure modes.)

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flarp /flarp/ n.

[Rutgers University] Yet another metasyntactic variable (see foo). Among those who use it, it is associated with a legend that any program not containing the word `flarp' somewhere will not work. The legend is discreetly silent on the reliability of programs which do contain the magic word.

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flash crowd

Larry Niven's 1973 SF short story "Flash Crowd" predicted that one consequence of cheap teleportation would be huge crowds materializing almost instantly at the sites of interesting news stories. Twenty years later the term passed into common use on the Internet to describe exponential spikes in website or server usage when one passes a certain threshold of popular interest (this may also be called slashdot effect).

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flat adj.

1. [common] Lacking any complex internal structure. "That bitty box has only a flat filesystem, not a hierarchical one." The verb form is flatten. 2. Said of a memory architecture (like that of the VAX or 680x0) that is one big linear address space (typically with each possible value of a processor register corresponding to a unique core address), as opposed to a `segmented' architecture (like that of the 80x86) in which addresses are composed from a base-register/offset pair (segmented designs are generally considered cretinous).

Note that sense 1 (at least with respect to filesystems) is usually used pejoratively, while sense 2 is a Good Thing.

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flat-ASCII adj.

[common] Said of a text file that contains only 7-bit ASCII characters and uses only ASCII-standard control characters (that is, has no embedded codes specific to a particular text formatter markup language, or output device, and no meta-characters). Syn. plain-ASCII. Compare flat-file.

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flat-file adj.

A flattened representation of some database or tree or network structure as a single file from which the structure could implicitly be rebuilt, esp. one in flat-ASCII form. See also sharchive.

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flatten vt.

[common] To remove structural information, esp. to filter something with an implicit tree structure into a simple sequence of leaves; also tends to imply mapping to flat-ASCII. "This code flattens an expression with parentheses into an equivalent canonical form."

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flavor n.

1. [common] Variety, type, kind. "DDT commands come in two flavors." "These lights come in two flavors, big red ones and small green ones." "Linux is a flavor of Unix" See vanilla. 2. The attribute that causes something to be flavorful. Usually used in the phrase "yields additional flavor". "This convention yields additional flavor by allowing one to print text either right-side-up or upside-down." See vanilla. This usage was certainly reinforced by the terminology of quantum chromodynamics, in which quarks (the constituents of, e.g., protons) come in six flavors (up, down, strange, charm, top, bottom) and three colors (red, blue, green) -- however, hackish use of `flavor' at MIT predated QCD. 3. The term for `class' (in the object-oriented sense) in the LISP Machine Flavors system. Though the Flavors design has been superseded (notably by the Common LISP CLOS facility), the term `flavor' is still used as a general synonym for `class' by some LISP hackers.