:for values of: [MIT] A common rhetorical maneuver at MIT is to use any of the canonical {random numbers} as placeholders for variables. "The max function takes 42 arguments, for arbitrary values of 42." "There are 69 ways to leave your lover, for 69 = 50." This is especially likely when the speaker has uttered a random number and realizes that it was not recognized as such, but even `non-random' numbers are occasionally used in this fashion. A related joke is that pi equals 3 —- for small values of pi and large values of 3.
Historical note: this usage probably derives from the programming language MAD (Michigan Algorithm Decoder), an Algol-like language that was the most common choice among mainstream (non-hacker) users at MIT in the mid-60s. It had a control structure FOR VALUES OF X = 3, 7, 99 DO … that would repeat the indicated instructions for each value in the list (unlike the usual FOR that only works for arithmetic sequences of values). MAD is long extinct, but similar for-constructs still flourish (e.g. in UNIX's shell languages).
:fora: pl.n. Plural of {forum}.
:foreground: [UNIX] vt. To foreground a task is to bring it to the top of one's {stack} for immediate processing, and hackers often use it in this sense for non-computer tasks. "If your presentation is due next week, I guess I'd better foreground writing up the design document."
Technically, on a time-sharing system, a task executing in foreground is one able to accept input from and return output to the user; oppose {background}. Nowadays this term is primarily associated with {{UNIX}}, but it appears first to have been used in this sense on OS/360. Normally, there is only one foreground task per terminal (or terminal window); having multiple processes simultaneously reading the keyboard is a good way to {lose}.
:fork bomb: [UNIX] n. A particular species of {wabbit} that can be written in one line of C (`main() {for(;;)fork();}') or shell (`$0 & $0 &') on any UNIX system, or occasionally created by an egregious coding bug. A fork bomb process `explodes' by recursively spawning copies of itself (using the UNIX system call `fork(2)'). Eventually it eats all the process table entries and effectively wedges the system. Fortunately, fork bombs are relatively easy to spot and kill, so creating one deliberately seldom accomplishes more than to bring the just wrath of the gods down upon the perpetrator. See also {logic bomb}.
:forked: [UNIX; prob. influenced by a mainstream expletive] adj. Terminally slow, or dead. Originated when one system was slowed to a snail's pace by an inadvertent {fork bomb}.
:Fortrash: /for'trash/ n. Hackerism for the FORTRAN language,
referring to its primitive design, gross and irregular syntax,
limited control constructs, and slippery, exception-filled
semantics.
:fortune cookie: [WAITS, via UNIX] n. A random quote, item of
trivia, joke, or maxim printed to the user's tty at login time or
(less commonly) at logout time. Items from this lexicon have often
been used as fortune cookies. See {cookie file}.
:forum: n. [USENET, GEnie, CI$; pl. `fora' or `forums'] Any discussion group accessible through a dial-in {BBS}, a {mailing list}, or a {newsgroup} (see {network, the}). A forum functions much like a bulletin board; users submit {posting}s for all to read and discussion ensues. Contrast real-time chat via {talk mode} or point-to-point personal {email}.