Glossary
action Any task initiated in a script.
actual arguments The scalar values that are supplied to
a subroutine by the programmer when it is called. When &boxer(glove)
is called, 'glove' is the actual argument.
address operator A language construct for manipulating
the actual location of an object in the computer's memory. Not
needed in Perl.
alternatives In Perl, the term refers to alternatives with
regular expressions. They are separated with a single bar: |.
Normal Perl expressions are separated with two bars: ||.
architecture The "kind" of computer used, where
"kind" refers to all the computers that can run the
same binary code. Perl isn't fussy about architecture, whereas
C is.
argument Data supplied as input to a function, subroutine,
or program when the data is asked for. Also called a parameter.
ARGV The name of the array that contains the argument 'vector'
from the command line.
arithmetic operator A symbol, such as + or /, that informs
Perl to perform arithmetic.
array A list of values that has been named, each of which
has a unique key for identification. The key is numeric in an
ordinary array, and a string in an associative array.
array context The list of values, as opposed to a single
value, returned by an expression when required by the code calling
it. It can also mean those functions that have syntax that contains
the non-terminal LIST supply array contexts of any expressions
employed as an element of the list.
array literal A list of scalar literals that is separated
by commas and parenthesis, but contains no variables.
array value A list of scaler values with no name that can
be passed about within a script and passed to any function which
gives an array context.
array variable This is a named list that may be processed
by functions like splice and shift. These functions must have
an array name as their first argument.
ASCII American Standard Code for Information Interchange.
This is a 7-bit character code which represents 128 characters.
Some of these characters are used for communications control and
are not printable.
assignment A statement that is used to change the value
of a variable.
assignment operator An assignment statement that adapts
the value of a variable, i.e., $B -= 1 subtracts 1 from $B.
associative array Key-value pairs in a named list, which
are arranged so that any key can be used to find its associative
value.
associativity Deciding which operator to perform by its
precedence.
autoincrement To automatically add one to a value.
autosplit To automatically split a string or white space.
awk A text processing language that was a forerunner to
Perl.
BLOCK A structure in a Perl script that is constrained
by braces: {}.
block buffering Performing input and output one block at
a time, making the process more efficient.
Boolean context Determining truth based on one or zero;
on or off. Very handy when dealing with bits, which are either
one or zero.
browser A software program that will interpret HTML documents;
a synonym for a Web client.
BSD Stands for Berkeley Standard Distribution.
CGI Common Gateway Interface. This specification, among
other things, allows browsers to communicate with external viewers,
or other applications.
client A software program that makes requests for information
or services from another software program called a server
over a network connection, like the Internet. The client then
presents this information in the manner dictated by its hardware.
command Any character combination in a script that causes
the Perl interpreter to take some action.
compiler A program that reads another program, and then
parses that script into a form that can then be executed. C is
a language that uses a compiler.
data structure The form various pieces of data take in
relation to each other, like a data tree.
declaration A message to the computer to remember something,
but not to do something. The opposite of a statement in Perl.
delimiter Any character or string that places a limit on
the size of any text object in Perl.
DTD Document Type Definition. This is a mark-up language
specification.
domain name An alphabetic name for a computer host. This
is the name which is mapped to the machine's numeric IP address.
element In Perl, the basic component of an array. In HTML,
the unit of structure in HTML documents. HTML elements each have
their own tags.
environmental variable A variable device that allows the
user to pass on her preferences to a script in the form of a key/value
pair, similar to an element in an associative array.
EOF End Of File. Used with the print command to output
designated code between EOF markers.
expression Anything in Perl that requires a value, like
literals, variables, operators, functions, and subroutine calls.
FTP File Transfer Protocol. A method of file exchange over
networks and the Internet.
Gopher A protocol similar to FTP. Gopher is more sophisticated,
with its use of menus that can point to files, documents, links,
or searches of other information services.
global A variable designation that means the entire script
can read that variable. Opposite of a local variable.
hexidecimal A number that is base 16. The digits 1 through
15 are represented by the letters a through f. To use hexidecimals
in Perl, prefix them with 0x.
hits What happens to an HTML document when it has been
accessed by a user. Useful when discussing the frequency of access
a Web site, or server, is receiving.
home directory The directory in which the user gains access
by their login.
HTML HyperText Markup Language. The language that creates
Web documents when viewed by a Web browser.
HTTP HyperText Tansfer Protocol. This is the protocol the
Web uses to transfer HTML documents.
hypertext Text that is not bound to a single flow for perception.
Web-based hypertext is not bound to a single server for creating
significance.
IIS Internet Information Server. The Internet service package
written by Microsoft for the NT.
interpreter A program that reads another program, and then
performs the tasks specified in the read script. Perl uses an
interpreter, which is different from a language like C, which
uses a compiler.
ISO International Standards Organization. The world-wide
organization that sets the standards for many things.
Internet The globally distributed collection of computers
and computer networks using the TCP/IP suite as their standard
for communication.
IP Stands for Internet protocol.
key A piece of data that is used to find another piece
of data, the value, in an associative array.
label A kind of key that is linked to a statement in Perl
so it can be used elsewhere in a script.
LAN Local Area Network. Typically a network of computers
wired together in the same geographical location.
list In Perl, a set of values arranged in an ordered set.
literal Any number or string in a Perl script that renders
an actual value instead of a possible value.
local A variable designation that limits the value of that
variable to a specific, or local, area of a script.
loop A programming structure that allows a script to perform
an action more than once.
MIME Multipurpose Internet Mail Extensions. This is a specification
for multimedia documents.
matrix The set of computers, including large commercial
networks and the Internet, that can share e-mail through gateways.
null character Any character with the ASCII value of "0".
null list Any list with the value of "0".
null string Any string comprised of 0 characters. A string
containing a null character is not a null string, however, because
it would then contain one character.
octal A number with the base of 8, running from 0 to 7.
To use an octal in Perl, use the prefix "0".
operator A Perl function that has a special syntax or symbol.
package A unit in Perl code that limits access from the
other areas of the script, protecting its variables and subroutines
from being changed by another part of the script.
packet A unit of data used in data transmission.
parsing The process of turning a script into a syntax tree,
which can then be read by an interpreter and executed.
path The series of file names that indicates which directories
must be navigated in order to find a specific file.
Perl Stands for Practical Extraction and Reporting Language.
pipe The mechanism by which two adjacent programs are joined
within a pipeline. It is done by connecting the standard output
of one process to the standard input of another. It can also mean
the act of moving data through one of these connections.
pipeline An orchestration by which information is passed
from application to application in sequence.
process An applicaton that is currently being executed.
From UNIX.
recursion Defining something in terms of itself.
regular expressions In Perl, a code line that defines a
pattern for a search to match.
return value The value produced when a subroutine or expression
is called in Perl.
RFC Request For Comment. These are the documents that lay
down the specifications for the various technologies, protocols,
and standards used by the Internet.
scalar A simple value in Perl, like a number or a string.
scalar literal An actual quoted string or number that appears
in a Perl script. This is the opposite of a variable.
SGML Standard Generalized Mark-up Language. This is the
standard for defining a mark-up language, like HTML.
server A software application that provides services or
data in response to client requests.
site One or more files that deal with a self-contained
idea. They may be found on a Web, FTP, or Gopher server.
slice A method of selecting elements from an array.
statement In Perl, a command to the computer to do something
next. Opposite of a declaration.
subroutine A specified piece of Perl code that, once defined,
can be called into action anywhere else in the script.
tags The term given to the HTML codes that are used by
the Web browser to interpret the document.
Telnet This protocol is used to access and run a machine
from a remote location. It uses terminal emulation to share data
across a network.
UNIX An operating system that has variations which run
on many different types of machines.
URL Universal Resource Locator. This is the method for
addressing a Web file.
Usenet A system for distributing asynchonous text discussion
among co-operating computer hosts. Usenet is divided into newsgroups,
each specializing in a particular topic.
value An actual string or number.
variable A string or number used as a storage place in
a script for values.
working directory The current directory.
WWW Stands for World Wide Web.