process of being connected to the network or a worker machine; obtaining data from or placing data into storage
access time
the time a computer requires to locate data in its external storage
allocate
to assign storage locations to a program; to assign a specific amount of computer resources to an organization or individual
alphanumeric data
data containing alphabetic characters and digits; may contain special characters and the space character
anonymous FTP
accessing a machine with the FTP protocol without having to obtain an account on that machine; accessing a public repository of material that can be obtained using FTP and logging in using the account name anonymous
array
a group of related items; an orderly structure of items or values
ASCII
(American Standard Code for Information Interchange) default file transfer mode
asynchronous
transmission by individual bytes, not related to specific timing on the transmitting end
B
backbone
high-speed connection within a network which connects shorter (usually slower) branch circuits
backup
a copy of a file made to ensure that the information will not be lost if the original is destroyed; a backup copy of a file can be made by saving it under a different name; backup copies of files are made periodically on the systems.
bandwidth
the difference, in Hertz (Hz), between the highest and lowest frequencies of a transmission channel; the greater the bandwidth the "faster" the line
batch
a group of similar records or programs that are treated as a single unit for processing; the user must wait for the results, and data cannot be supplied during the execution of the program
batch processing
a systems approach to processing in which a number of jobs are executed by an operating system or monitor program with no user interaction
baud
unit of measure of data transmission speed; usually bits/second; may differ from the number of data bits transmitted per second by the use of techniques that encode two or more bits on a single cycle (i.e., 1200bps and 2400bps modems actually transmit at 600 baud)
binary
refers to a condition that has two possible different values; a number system having a base of two (0 and 1)
binhex
(BINary HEXadecimal) method of converting non-text files (non-ASCII) into ASCII; Internet e-mail can only handle ASCII
bit
contraction of "binary digit"; the smallest unit of information in a binary system; a one or zero condition
bridge
a device that acts as a connector between similar local area networks
broadcast
a packet delivery system that delivers a copy of a given packet to all hosts attached to it
browser
a Web client; a program that retrieves and displays information from the Web; also called a user agent
bug
an error in a program (also known as a glitch)
C
character
letter, number, punctuation, control figure, or any other symbol contained in a message
client
the user of a network service; a system or program that requests the activity of one or more systems or programs (the servers) to acomplish specific tasks; does its own processing
code
the unit of instructions that can be executed on a computer; to represent data in a symbolic form acceptable to a computer; programming commands
column
a character position on a terminal screen; a vertical arrangement of characters or expressions (see row)
command
an electronic pulse or signal that starts, stops, or continues an operation; instruction telling the computer what the user wants done; a command string includes all of its parameters and qualifiers
compatibility
the ability of an instruction to be translated or used by more than one type of computer
compiler
a program that translates another program written in a high-level language into computer-readable code (machine code)
concatenate
to combine or link together as a unit; to chain
configuration
the way in which machines, equipment, or systems are linked to work as one
crash
a more or less catastrophic system failure that normally requires an unscheduled dead-start
cue
to call for
D
data
the elements used for communication or computer-related processes
database
an electronic file processing system organized by fields, records, and files; a collection of programs that enables you to enter, organize, and select data in a database
data integrity
a performance measure based on the rate of undetected errors
dedicated
a term used to indicate that a computing resource is reserved to a specific purpose
default
information the operating system assumes as input if the information is not explicitly provided
device
a drive and its controlling logic, such as a disk drive or terminal (e.g., mass-storage controller)
directory
a group of files stored on a disk in a specific place (e.g., the user file directory); sometimes called a folder; the command listing those files
domain
defines a region of jurisdiction for name assignment and of responsibility for name-to-address translation; any computer within the host; in the Internet, a part of the naming hierarchy
download
the process of sending configuration parameters, opening software or related data from a central source to remote stations
E
e-mail
electronic mail; any communications service that permits the electronic transmission and storage of messages and attached or enclosed files
editor (text)
a program that permits interactive users to create or modify text (e.g., EDT, EVE, LSE, EMACS, VI, PICO, and WYLBUR)
emulation
the imitation of a computer system performed by a combination of hardware and software that allows programs to run between incompatible systems
error message
message sent by the system when some action you have requested fails
Ethernet
refers to one of many different methods of transmitting data; name of the coaxial cable used to connect network communication devices and computers; designed by Xerox and characterized by 10 megabit/second baseband transmission over shielded coaxial cable
execute
to perform the operations specified by one or more computer instructions
F
file extension
one to three alphanumeric characters usually chosen by the program to describe the class of information in a file; sometimes called the filetype because it often indicates the nature of the file; the extension is separated from the filename by a period
filenames
UNIX filenames may contain any character except the / character and can be any length (up to a max of around 1024 characters). Upper and Lower case characters are treated as different characters. While there are no enforced rules about extensions, many compilers insist on them.
filter
Any program which reads from standard input, performs some unique permutation on the input and then writes the results on standard output.
firewall
combination of hardware and software that separates a LAN into two or more parts for security purposes; an application that acts as a boundary between networks to control access and improve the flow of network traffic
flat file
A text file. Unlike many other systems, standard UNIX applications use text files instead of imposing particular formatting conventions on the document. This results in much easier sharing of information between applications
FTP
(File Transfer Protocol) a user interface to the network; a program that allows you to transfer files to and from a remote network site
function
a computer subroutine; a subroutine that performs a calculation with variables provided by a program and supplies the program with a single result
G
gateway
a device that acts as a connector between two logically separate networks; interconnects two otherwise incompatible networks, network nodes, subnetworks, or devices
glitches
mistakes, usually referring to software
H
hardware
all of the equipment and physical parts of a computer system
host
information processor that provides supporting services to users and/or other processors; server (remote) with which the FTP is to communicate. Local host is the system you are working from; remote hosts are all the other systems.
hostname
sets or prints the name of the current host system
I
interface
something that links or joins two pieces of hardware, systems, devices, etc.; a shared boundary defined by common physical interconnection characteristics, signal characteristics, and meanings of interchanged signals
interoperability
the ability of software and hardware on multiple machines from multiple vendors to communicate meaningfully
J
job
one or more duties or programs that are treated as a unit of work by the computer
L
language
a specific set of characters that is used to form the words or symbols that allow the computer programmer to manage computer operations
logical file
usually refers to the data preceding an end of file in a physical file
logical name
a user-specified name for any portion or all of a file specification
logging in/on
opens the connection to the host
logging off/out
closes the connection to the remote host and exits (LO, BYE, and QUIT are various log-off commands)
M
memory
data storage in the computer itself; used while running or editing programs
MIME
Multi-purpose Internet Mail Extensions; the standard for Internet mail. It is the specification that offers a way to interchange text--with languages with different character sets--and multimedia e-mail among many different computer systems that use Internet mail standards.
N
network
a group of machines connected together so they can transmit information to one another. There are two kinds of networks: local networks and remote networks.
network path
a series of machine names used to direct electronic mail from one user to another
newline
UNIX does not put both the Carriage Return and Line Feed characters at the end of each line of text. Instead, it puts just the Line Feed character. Because this one character serves both to mark the end of a line and to advance a terminal to the beginning of the next line, it is referred to as the Newline character
node
a computer attached to a network; often a terminating point of a computer or terminal that has the ability to send or receive information over the communication line
node name
the unique name by which each computer is known on the network.
O
operating system
the program that runs the computer and controls the execution of all other programs
operation
one processing step on a computer
output
the final results of a program
P
parameter
a variable that is assigned a specific value for a particular purpose or process (or command)
passwords
UNIX passwords are 8 characters in length and can include almost any character that can be typed. Upper and lower case characters are different. The characters which cannot (or should not) be used include #, @, DEL, and backspace.
peripheral devices
hardware used with the computer for purposes other than processing the data itself, such as printers, tape and disk drives, and terminals
PING
(Packet Internet Groper) a TCP/IP utility that sends packets of information to a computer on a network; it can be used to determine whether a computer is connected to the Internet
platform
an individual hardware or software architecture or an operating system
port
an electrical and mechanical connection where a device is connected to a transmission medium (perhaps a cable)
protocol
a formal set of operating rules governing the format, timing, and error control of transmissions on a network; the protocol that networks use to communicate with each other, e.g., IP, DECNET, and UDP
protocol emulator
a program that lets the hardware think it is another kind of hardware; usually used when dialing up another computer where one computer is not compatible with another
proxy
the procedure that permits a remote user to access a specific account at the local node, without supplying the username and password
Q
queue
a group of items awaiting processing; a waiting line or area
R
RAM
Random Access Memory; read-write volatile memory where data stored is lost if power is turned off
read
to take information from a storage device
record
a group of items that are related and treated as one unit
refresh
(the screen)
returning the display to its prior state before interruption by a system message, usually achieved by pressing CTRL-W
response time
the elapsed time between the generation of the last character of a message at a terminal and the receipt of the first character of the reply (including terminal delay and network delay)
ROM
Read Only Memory; nonvolatile memory manufactured with predefined data content, permanently stored
row
a character position on a terminal screen; a horizontal arrangement of characters or expressions (see column)
run
the process of executing a computer program
S
server
a provider of network service; typically stores information and software; a system or program that receives requests from one or more client systems or programs to perform acitivities that allow the client to accomplish certain tasks
server root
where the actual server software and all of its support files are stored
sessions
period during which a participant maintains dialog on a terminal
software
a general term for any kind of computer program or programs held in some kind of storage medium and loaded into read/write memory (RAM) for execution
special characters
Characters which cause special and/or unexpected things to happen. There are two major sets of these characters: special terminal and special shell characters (see tables following this glossary). Note: Not all shells support or allow all of these special characters.
standard error
The standard place where error messages from programs are sent. By default it will be the user's terminal. It is separate from the output so that it is possible to notice errors automatically.
standard input
The standard place from which input is received by a program. By default it will be the user's keyboard.
standard output
The standard place where output is directed from a program. By default it will be the user's terminal.
statement
an expression in a programming language that specifies a process
string
a connected sequence of characters
synchronous
data communications in which transmissions are sent at a fixed rate with the sending and receiving devices synchronized
T
Telnet
a terminal emulation protocol (or a program based on that protocol); the Internet standard protocol for remote terminal connection service
terminal
an input/output device for a computer that usually has a keyboard for input and a video screen/monitor for output
terminal server
special-purpose computer that has places to plug in modems on one side and a connection to a LAN or host machine on the other side; does the work of answering the calls and passes the connections on to the appropriate node
U
upload
the process of sending a file to a remote computer through a network
uucp
(UNIX-to-UNIX Copy) originally, a UNIX program that permitted file transfer between two UNIX-based PCs via a dial-up connection. The term also refers to a UNIX networking protocol or to a network using that protocol.
V
variable
a symbol whose numeric value can change
virtual circuit
a network service that allows two processes to communicate as if they were directly connected to each other
virtual reader
the temporary holding place for files that have been sent to a username and have not been processed by the RECEIVE command
W
white space
Any string of spaces and/or tabs is referred to as whitespace. Under certain circumstances (depending on the shell and/or function being used) the Newline character may also be counted as whitespace. The name comes simply from the appearance of these characters on a screen: white.
wildcard
Any special characters used by a shell to represent a sequence of characters in a filename. UNIX uses * to represent any string of characters (not containing a /), ? to represent any one character (except for /) and [..] to represent any one character from the set between the square brackets (again, / cannot be matched).
