appendix-d.html

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<P>C shell&#151;A user interface for UNIX written by Bill Joy at Berkeley. It features C <BR>
programming-like syntax.

<P>CAD&#151;Computer-aided design.

<P>cast&#151;Programming construct to force type conversion.

<P>cat&#151;Concatenate files command.

<P>CD-ROM&#151;Compact Disk-Read Only Memory. Computer-readable data stored on the
same physical form as a musical CD. Large capacity, inexpensive, slower than a hard disk, and
limited to reading. There are versions that are writable (CD-R, CD Recordable) and other
formats that can be written to once or many times.

<P>CGI&#151;Common Gateway Interface. A means of transmitting data between Web pages
and programs or scripts executing on the server. Those programs can then process the data
and send the results back to the user's browser through dynamically creating HTML.

<P>character special&#151;A device file that is used to communicate with character-oriented I/O
devices like terminals, printers, or network communications lines. All I/O access is treated as
a series of bytes (characters).

<P>characters, alphabetic&#151;The letters A through Z and a through z.
</P>

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<P>characters, alphanumeric&#151;The letters A through Z and a through z, and the numbers 0 <BR>
through 9.

<P>characters, control&#151;Any nonprintable characters. The characters are used to control
devices, separate records, and eject pages on printers.

<P>characters, numeric&#151;The numbers 0 through 9.

<P>characters, special&#151;Any of the punctuation characters or printable characters that are
not alphanumeric. Include the space, comma, period, and many others.

<P>child process&#151;See subprocess.

<P>child shell&#151;See subshell.

<P>class&#151;A model of objects that have attributes (data) and behavior (code or functions). It
is also viewed as a collection of objects in their abstracted form.

<P>command-line editing&#151;UNIX shells support the ability to recall a previously entered
command, modify it, and then execute the new version. The command history can remain
between sessions (the commands you did yesterday can be available for you when you log in
today). Some shells support a command-line editing mode that uses a subset of the
vi, emacs, or gmacs editor commands for command recall and modification.

<P>command-line history&#151;See command-line
editing.

<P>command-line parameters&#151;Used to specify parameters to pass to the execute program
or procedure. Also known as command-line arguments.

<P>configuration files&#151;Collections of information used to initialize and set up the
environment for specific commands and programs. Shell configuration files set up the user's environment.

<P>configuration files, shell&#151;For Bourne shell:
/etc/profile and $HOME/.profile.

<P>For Korn and pdksh shells: /etc/profile,
$HOME/.profile, and ENV= file.

<P>For C and tcsh shells: /etc/.login, /etc/cshrc,
$HOME/.login, $HOME/.cshrc, and $HOME/.logout. Older versions might not support the first two files listed.

<P>For bash: /etc/profile/, $HOME/.bash_profile,
$HOME/.bash_login, $HOME/.profile, $HOME/.bashrc, and
~/.bash_logout.

<P>CPU&#151;Central Processing Unit. The primary &quot;brain&quot; of the computer&#151;the calculation
engine and logic controller.

<P>daemon&#151;A system-related background process that often runs with the permissions of
root and services requests from other processes.

<P>DARPA&#151;(U.S. Department of) Defense Advanced Research Projects
Agency. Funded development of TCP/IP and ARPAnet (predecessor of the Internet).

<P>database server&#151;See server, database.
</P>

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<P>device file&#151;File used to implement access to a physical device. This provides a consistent
approach to access of storage media under UNIX; data files and devices (like tapes and
communication facilities) are implemented as files. To the programmer, there is no real difference.

<P>directory&#151;A means of organizing and collecting files together. The directory itself is a
file that consists of a list of files contained within it. The root
(/) directory is the top level and every other directory is contained in it (directly or indirectly). A directory might contain
other directories, known as subdirectories.

<P>directory navigation&#151;The process of moving through directories is known as navigation.
Your current directory is known as the current working directory. Your login directory is known
as the default or home directory. Using the cd command, you can move up and down
through the tree structure of directories.

<P>DNS&#151;Domain Name Server. Used to convert between the name of a machine on the
Internet (name.domain.com) to the numeric address
(123.45.111.123).

<P>DOS&#151;Disk Operating System. Operating system that is based on the use of disks for the
storage of commands. It is also a generic name for MS-DOS and PC-DOS on the personal
computer. MS-DOS is the version Microsoft sells; PC-DOS is the version IBM sells. Both are
based on Microsoft code.

<P>double&#151;Double-precision floating point.

<P>dpi&#151;Dots per inch.

<P>EBCDIC&#151;Extended Binary Coded Decimal Interchange
Code. The code used to represent characters in memory for mainframe computers.

<P>ed&#151;A common tool used for line-oriented text editing.

<P>elm&#151;Interactive mail program.

<P>emacs&#151;A freely available editor now part of the GNU software distribution. Originally
written by Richard M. Stallman at MIT in the late 1970s, it is available for many platforms. It
is extremely extensible and has its own programming language; the name stands for editing
with macros.

<P>e-mail&#151;Messages sent through an electronic medium instead of through the local postal
service. There are many proprietary e-mail systems that are designed to handle mail within a
LAN environment; most of these are also able to send over the Internet. Most Internet (open)
e-mail systems make use of MIME to handle attached data (which can be binary).

<P>encapsulation&#151;The process of combining data (attributes) and functions (behavior in the
form of code) into an object. The data and functions are closely coupled within an object. Instead
of all programmers being able to access the data in a structure their own way, they have to use
the code connected with that data. This promotes code reuse and standardized methods of
working with the data.
</P>

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<P>environment variables&#151;See variables,
environmental.

<P>Ethernet&#151;A networking method where the systems are connected to a single shared bus
and all traffic is available to every machine. The data packets contain an identifier of the
recipient, and that is the only machine that should process that packet.

<P>expression&#151;A constant, variable, or operands and operators combined. Used to set a
value, perform a calculation, or set the pattern for a comparison (regular expressions).

<P>FIFO&#151;First In, First Out. See pipe, named.

<P>file&#151;Collection of bytes stored on a device (typically a disk or tape). Can be source code,
executable binaries or scripts, or data.

<P>file compression&#151;The process of applying mathematical formulas to data, typically
resulting in a form of the data that occupies less space. A compressed file can be uncompressed,
resulting in the original file. When the compress/uncompress process results in exactly the same file
as was originally compressed, it is known as lossless. If information about the original file is
lost, the compression method is known as lossy. Data and programs need lossless compression;
images and sounds can stand lossy compression.

<P>file, indexed&#151;A file based on a file structure where data can be retrieved based on
specific keys (name, employee number, and so on) or sequentially. The keys are stored in an
index. This is not directly supported by the UNIX operating system; usually implemented by the
programmer or by using tools from an ISV. A typical form is known as
ISAM.

<P>file, line sequential&#151;See file, text.

<P>file, sequential&#151;This phrase can mean either a file that can only be accessed sequentially
(not randomly), or a file without record separators (typically fixed length, but UNIX does not
know what that length is and does not care).

<P>file, text&#151;A file with record separators. Can be fixed or variable length; UNIX tools can
handle these files because the tools can tell when the record ends (by the separator).

<P>filename&#151;The name used to identify a collection of data (a file). Without a pathname, it
is assumed to be in the current directory.

<P>filename generation&#151;The process of the shell interpreting metacharacters (wildcards) to
produce a list of matching files. This is referred to as filename expansion or globbing.

<P>filename, fully qualified&#151;The name used to identify a collection of data (a file) and its
location. It includes both the path and name of the file; typically, the pathname is fully
specified (absolute). See also pathname and pathname,
absolute.

<P>filesystem&#151;A collection of disk storage that is connected (mounted) to the directory
structure at some point (sometimes at the root). Filesystems are stored in a disk partition and
are sometimes referred to as being the disk partition.
</P>

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<P>finger&#151;User information lookup program.

<P>firewall&#151;A system used to provide a controlled entry point to the internal network from
the outside (usually the Internet). This is used to prevent outside or unauthorized systems
from accessing systems on your internal network. The capability depends on the individual
software package, but the features typically include filter packets and filter datagrams, system (name
or IP address) aliasing, and rejecting packets from certain IP addresses. In theory, it provides
protection from malicious programs or people on the outside. It can also prevent internal
systems from accessing the Internet on the outside. The name comes from the physical barrier
between connected buildings or within a single building that is supposed to prevent fire from
spreading from one to another.

<P>flags&#151;See options.

<P>float&#151;Single-precision floating point.

<P>foreground&#151;Programs running while connected to the interactive session.

<P>fseek&#151;Internal function used by UNIX to locate data inside a file or filesystem. ANSI
standard fseek accepts a parameter that can hold a value of +2 to -2 billion. This function, used
by the operating system, system tools, and application programs, is the cause of the 2GB file
and filesystem size limitation on most systems. With 64-bit operating systems, this limit is
going away.

<P>FSF&#151;Free Software Foundation.

<P>FTP&#151;File Transfer Protocol or File Transfer Program. A system-independent means of
transferring files between systems connected via TCP/IP. Ensures that the file is transferred <BR>
correctly, even if there are errors during transmission. Can usually handle character set
conversions (ASCII/EBCDIC) and record terminator resolution (linefeed for UNIX, carriage
return and linefeed for MS/PC-DOS).

<P>gateway&#151;A combination of hardware, software, and network connections that provides a
link between one architecture and another. Typically, a gateway is used to connect a LAN or
UNIX server with a mainframe (that uses SNA for networking, resulting in the name SNA
gateway). A gateway can also be the connection between the internal and external network (often
referred to as a firewall). See also firewall.

<P>GID&#151;Group ID number.

<P>globbing&#151;See filename generation.

<P>GNU&#151;GNU stands for GNU's Not UNIX, and is the name of free useful software
packages commonly found in UNIX environments that are being distributed by the GNU project
at MIT, largely through the efforts of Richard Stallman. The circular acronym name
(&quot;GNU&quot; containing the acronym GNU as one of the words it stands for) is a joke on Richard
Stallman's part. One of the textbooks on operating system design is titled
XINU: XINU Is Not UNIX, and GNU follows in that path.
</P>

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<P>GPL&#151;GNU General Public License.

<P>grep&#151;A common tool used to search a file for a pattern.
egrep and fgrep are newer versions. egrep allows the use of extended (hence the
e prefix) regular expressions; fgrep uses limited expressions for faster (hence the
f prefix) searches.

<P>GUI&#151;Graphical user interface.

<P>here document&#151;The &lt;&lt; redirection operator, known as
here document, allows keyboard input (stdin) for the program to be included in the script.

<P>HTML&#151;Hypertext Markup Language. Describes World Wide Web pages. It is the
document language that is used to define the pages available on the Internet through the use of tags.
A browser interprets the HTML to display the desired information.

<P>i-node&#151;Used to describe a file and its storage. The directory contains a cross-reference
between the i-node and pathname/filename combination. Also known as
inode. A file's entry in disk data structure (ls