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.