1. <operating system> The {Unix} {superuser} account (with
	user name "root" and user ID 0) that overrides file
	permissions.  The term {avatar} is also used.  By extension,
	the privileged system-maintenance login on any {operating
	system}.

	See {root mode}, {go root}, {wheel}.

	[{Jargon File}]

	(1994-10-27)

	2. <operating system> {root directory}.

	(1996-11-21)

	3. <data> {root node}.

	(1998-11-14)

1. A discrepancy between a computed, observed, or measured
	value or condition and the true, specified, or theoretically
	correct value or condition.

	2. <programming> A mental mistake made by a programmer that
	may result in a program {fault}.

	3. (verb) What a program does when it stops as result of a
	programming error.

	(2000-03-28)

[{Usenet}] 1. To duplicate a portion (or whole) of another's
	message (typically with attribution to the source) in a reply
	or followup, for clarifying the context of one's response.
	See the discussion of inclusion styles under "Hacker Writing
	Style".

	2. [{C}] "#include <disclaimer.h>" has appeared in {sig
	blocks} to refer to a notional "standard {disclaimer} file".

	[{Jargon File}]

<software> (Or "option", "flag", "switch", "option switch") An
	argument to a command that modifies its function rather than
	providing data.  Options generally start with "-" in {Unix} or
	"/" in {MS-DOS}.  This is usually followed by a single letter
	or occasionally a digit.

	Some commands require each option to be a separate argument,
	introduced by a new "-" or "/", others allow multiple option
	letters to be concatenated into a single argument with a
	single "-" or "/", e.g. "ls -al".  A few Unix commands
	(e.g. {ar}, {tar}) allow the "-" to be omitted.  Some options
	may or must be followed by a value, e.g. "cc prog.c -o prog",
	sometimes with and sometimes without an intervening space.

	{getopt} and {getopts} are commands for parsing command line
	options.  There is also a {C} library routine called getopt
	for the same purpose.

	(1996-12-11)

<security> An arbitrary string of characters chosen by a user
	or {system administrator} and used to authenticate the user
	when he attempts to log on, in order to prevent unauthorised
	access to his account.

	A favourite activity among unimaginative {computer nerds} and
	{crackers} is writing programs which attempt to discover
	passwords by using lists of commonly chosen passwords such as
	people's names (spelled forward or backward).  It is
	recommended that to defeat such methods passwords use a
	mixture of upper and lower case letters or digits and avoid
	proper names and real words.  If you have trouble remembering
	random strings of characters, make up an acronym like
	"ihGr8trmP" ("I have great trouble remembering my password").

	(1994-10-27)

Common term for "computer", usually when considered at the
	hardware level.  The {Turing Machine}, an early example of
	this usage, was however neither hardware nor software, but
	only an idea.

	[Earlier use?]

	(1995-02-15)

1. A program which provides some service to other ({client})
	programs.  The connection between client and server is
	normally by means of {message passing}, often over a
	{network}, and uses some {protocol} to encode the client's
	requests and the server's responses.  The server may run
	continuously (as a {daemon}), waiting for requests to arrive
	or it may be invoked by some higher level daemon which
	controls a number of specific servers ({inetd} on {Unix}).

	There are many servers associated with the {Internet}, such as
	those for {HTTP}, {Network File System}, {Network Information
	Service} (NIS), {Domain Name System} (DNS), {FTP}, {news},
	{finger}, {Network Time Protocol}.  On Unix, a long list can
	be found in /etc/services or in the {NIS} database "services".
	See {client-server}.

	2. A computer which provides some service for other computers
	connected to it via a network.  The most common example is a
	{file server} which has a local disk and services requests
	from remote clients to read and write files on that disk,
	often using {Sun}'s {Network File System} (NFS) {protocol} or
	{Novell Netware} on {PCs}.  Another common example is a {web
	server}.

	[{Jargon File}]

	(2003-12-29)

<database> A collection of {records} in a {relational database}.

	(1997-06-04)

See {followup}.

1. <operating system> (Or "erase") To make a file
	inaccessible.

	Usually this operation only deletes information from the
	tables the {file system} uses to locate named files; the
	file's contents still exist on {disk} and can sometimes be
	recovered by scanning the whole disk for strings which are
	known to have been in the file.  Files created subsequently on
	the same disk are quite likely to reuse the same blocks and
	thus overwrite the deleted file's data permanently.

	2. <character> The {control character} with {ASCII} code 127.
	Usually entering this character from the keyboard deletes the
	last character typed from the {input buffer}.  Sadly there is
	great confusion between {operating systems} and keyboard
	manufacturers as to whether this function should be assigned
	to the delete or {backspace} key/character.

	The choice of code 127 (binary 1111111) is not arbitrary but
	dates back to the use of {paper tape} for input.  The delete
	key rewound the tape by one character and punched out all
	seven holes, thus obliterating whatever character was there
	before.  The tape reading software ignored any delete
	characters in the input.

	(1996-12-01)

<operating system> All activities involved in completing any
	project on a computer from start to finish.  A job may involve
	several {processes} and several {programs}.

	This term originates from a time when a user would manually
	submit a job as a deck of {punched cards} which would
	typically include {source code} interspersed with {job control
	language} instructions to guide phases of the job such as
	{compilation}, {linking}, {execution} and printing.

	(2005-03-16)

<algorithm> The arrangement of a number of related operations
	in time.

	There are several kinds of scheduling related to computers:

	{instruction scheduling} - sequencing the instructions
	executed by the {CPU}

	{multitasking} ("process scheduling") - sharing a CPU between
	several processes

	{application} {software} to help organise your daily meetings
	etc.

	{task scheduling} - {algorithms} to solve the general problem
	of satisfying time and resource {constraints} between a number
	of tasks.

	Compare {planning}.

	(1998-04-25)

<graphics> (Or "tone", "luminance", "value", "luminosity",
	"lightness") The coordinate in the {HSB} {colour model} that
	determines the total amount of light in the colour.  Zero
	brightness is black and 100% is white, intermediate values are
	"light" or "dark" colours.

	The other coordinates are {hue} and {saturation}.

	(1999-07-05)