Perl
Overview
Introduction
Why yet
another utility?
Beginning
Perl
Invoking Perl
Documentation on
perl
Perl Scripts
Variables
Input
and output
Files and
redirection
Pipes
The DATA
filehandle
Fields
Control structures
Predefined Perl
Functions
Modules
Regular expressions
Single
character translation
String
editing
Perl and the Kernel
Quality
code
When do I use Perl?
Summary
Exercises
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Modules
A Perl module is a collection of Perl programs written
to be used in other programs. You can write your own, or you can
use modules written by other people. Some modules are included with
each distribution of Perl, and others are made freely available on
the Web. The web site www.cpan.org
("Comprehensive Perl Archive Network") is the main place to go to
find out what is available. The site is continually growing, and at
the time of writing contained over 1600 modules, including modules
in the following areas:
- security, encryption and authentication;
- database support for most commercial databases;
- web support, including HTML parsers and HTTP servers;
- email clients and servers;
- mathematics;
- image manipulation;
- archiving and file conversion;
- interfaces to operating systems, including MacOS, OS2 and
Windows;
- hardware drivers; and
- specialised computational modules, such as Neural Networks and
Artificial Intelligence.
In order to use a module, include the line
use name-of-module;
at the start of your program.
Worked example
Write a Perl script to take two arguments, considered to be
filenames, and copy the contents of the first file to the
second.
Solution: Use the copy function in
the File::Copy module:
use File::Copy;
copy($ARGV[0], $ARGV[1]) or die "Cannot perform copy"
Note that we have checked the successful completion of the
copy function and generated an error message if it
failed.
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