UBD /U-B-D/ [abbreviation for `User Brain Damage'] An abbreviation used to close out trouble reports obviously due to utter cluelessness on the user's part. Compare pilot error; oppose PBD; see also brain-damaged.
UN*X n. Used to refer to the UNIX operating system (a trademark of AT&T) in writing, but avoiding the need for the ugly (TM) typography. Also used to refer to any or all varieties of Unixoid operating systems. Ironically, lawyers now say that the requirement for the TM-postfix has no legal force, but the asterisk usage is entrenched anyhow. It has been suggested that there may be a psychological connection to practice in certain religions (especially Judaism) in which the name of the deity is never written out in full, e.g., `YHWH' or `G--d' is used. See also glob.
undefined external reference excl. [UNIX] A message from UNIX's linker. Used in speech to flag loose ends or dangling references in an argument or discussion.
under the hood [hot-rodder talk] prep.
undocumented feature n. See feature.
UNIX /yoo'niks/ [In the authors' words, "A weak pun on Multics"] n. (also `Unix') An interactive time-sharing system invented in 1969 by Ken Thompson after Bell Labs left the Multics project, originally so he could play games on his scavenged PDP-7. Dennis Ritchie, the inventor of C, is considered a co-author of the system. The turning point in UNIX's history came when it was reimplemented almost entirely in C during 1972--1974, making it the first source-portable OS. UNIX subsequently underwent mutations and expansions at the hands of many different people, resulting in a uniquely flexible and developer-friendly environment. By 1991, UNIX had become the most widely used multiuser general-purpose operating system in the world. Many people consider this the most important victory yet of hackerdom over industry opposition (but see UNIX Weenie and UNIX Conspiracy for an opposing point of view). See Version 7, BSD, USG UNIX.
UNIX brain damage n. Something that has to be done to break a network program (typically a mailer) on a non-UNIX system so that it will interoperate with UNIX systems. The hack may qualify as `UNIX brain damage' if the program conforms to published standards and the UNIX program in question does not. UNIX brain damage happens because it is much easier for other (minority) systems to change their ways to match non-conforming behavior than it is to change all the hundreds of thousands of UNIX systems out there.
An example of UNIX brain damage is a kluge in a mail server to recognize bare line feed (the UNIX newline) as an equivalent form to the Internet standard newline, which is a carriage return followed by a line feed. Such things can make even a hardened jock weep.
UNIX conspiracy [ITS] n. According to a conspiracy theory long popular among ITS and TOPS-20 fans, UNIX's growth is the result of a plot, hatched during the 1970s at Bell Labs, whose intent was to hobble AT&T's competitors by making them dependent upon a system whose future evolution was to be under AT&T's control. This would be accomplished by disseminating an operating system that is apparently inexpensive and easily portable, but also relatively unreliable and insecure (so as to require continuing upgrades from AT&T). This theory was lent a substantial impetus in 1984 by the paper referenced in the back door entry.
In this view, UNIX was designed to be one of the first computer viruses (see virus) --- but a virus spread to computers indirectly by people and market forces, rather than directly through disks and networks. Adherents of this `UNIX virus' theory like to cite the fact that the well-known quotation "UNIX is snake oil" was uttered by DEC president Kenneth Olsen shortly before DEC began actively promoting its own family of UNIX workstations. (Olsen now claims to have been misquoted.)
UNIX weenie [ITS] n.
unixism n. A piece of code or a coding technique that depends on the protected multi-tasking environment with relatively low process-spawn overhead that exists on virtual-memory UNIX systems. Common unixisms include: gratuitous use of `fork(2)'; the assumption that certain undocumented but well-known features of UNIX libraries such as `stdio(3)' are supported elsewhere; reliance on obscure side-effects of system calls (use of `sleep(2)' with a 0 argument to clue the scheduler that you're willing to give up your time-slice, for example); the assumption that freshly allocated memory is zeroed; and the assumption that fragmentation problems won't arise from never `free()'ing memory. Compare vaxocentrism; see also New Jersey.
unleaded adj. Said of decaffeinated coffee, Diet Coke, and other imitation programming fluids. "Do you want regular or unleaded?" Appears to be widespread among programmers associated with the oil industry in Texas (and probably elsewhere). Usage: silly, and probably unintelligible to the next generation of hackers.
unswizzle v. See swizzle.
unwind the stack vi.
unwind-protect [MIT: from the name of a LISP operator] n. A task you must remember to perform before you leave a place or finish a project. "I have an unwind-protect to call my advisor."
upload /uhp'lohd/ v.
upthread adv. Earlier in the discussion (see thread), i.e., `above'. "As Joe pointed out upthread, ..." See also followup.
urchin n. See munchkin.
USENET /yoos'net/ or /yooz'net/ [from `Users' Network'] n. A distributed bboard (bulletin board) system supported mainly by UNIX machines. Originally implemented in 1979--1980 by Steve Bellovin, Jim Ellis, Tom Truscott, and Steve Daniel at Duke University, it has swiftly grown to become international in scope and is now probably the largest decentralized information utility in existence. As of early 1993, it hosts well over 1200 newsgroups and an average of 40 megabytes (the equivalent of several thousand paper pages) of new technical articles, news, discussion, chatter, and flamage every day.
The general theory behind this term is that there are two classes of people who work with a program: there are implementors (hackers) and lusers. The users are looked down on by hackers to some extent because they don't understand the full ramifications of the system in all its glory. (The few users who do are known as `real winners'.) The term is a relative one: a skilled hacker may be a user with respect to some program he himself does not hack. A LISP hacker might be one who maintains LISP or one who uses LISP (but with the skill of a hacker). A LISP user is one who uses LISP, whether skillfully or not. Thus there is some overlap between the two terms; the subtle distinctions must be resolved by context.
user-friendly adj. Programmer-hostile. Generally used by hackers in a critical tone, to describe systems that hold the user's hand so obsessively that they make it painful for the more experienced and knowledgeable to get any work done. See menuitis, drool-proof paper, Macintrash, user-obsequious.
user-obsequious adj. Emphatic form of user-friendly. Connotes a system so verbose, inflexible, and determinedly simple-minded that it is nearly unusable. "Design a system any fool can use and only a fool will want to use it." See WIMP Environment, Macintrash.
USG UNIX /U-S-G yoo'niks/ n. Refers to AT&T UNIX commercial versions after Version 7, especially System III and System V releases 1, 2, and 3. So called because during most of the lifespan of those versions AT&T's support crew was called the `UNIX Support Group'. See BSD, UNIX.
UTSL // [UNIX] n. On-line acronym for `Use the Source, Luke' (a pun on Obi-Wan Kenobi's "Use the Force, Luke!" in "Star Wars") --- analogous to RTFS (sense 1), but more polite. This is a common way of suggesting that someone would be better off reading the source code that supports whatever feature is causing confusion, rather than making yet another futile pass through the manuals, or broadcasting questions on USENET that haven't attracted wizards to answer them.
Once upon a time in Elder Days, everyone running UNIX had source. After 1978, AT&T's policy tightened up, so this objurgation was in theory appropriately directed only at associates of some outfit with a UNIX source license. In practice, bootlegs of UNIX source code (made precisely for reference purposes) were so ubiquitous that one could utter it at almost anyone on the network without concern.
Nowadays, free UNIX clones are becoming common enough that almost anyone can read source legally. The most widely distributed is probably Linux, with 386BSD (aka jolix) running second. Cheap commercial UNIXes with source such as BSD/386 are accelerating this trend.
UUCPNET n. The store-and-forward network consisting of all the world's connected UNIX machines (and others running some clone of the UUCP (UNIX-to-UNIX CoPy) software). Any machine reachable only via a bang path is on UUCPNET. See network address.