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Introducing UNIX and Linux

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

Exercises

1. Write a Perl script which takes one argument, assumed to be the URL of a web site (such as www.any.site.com), and displays on standard output the email address of postmaster at that site (postmaster@any.site.com). Ensure your script outputs suitable error messages if the script is run without exactly one argument.

2. Write a Perl script to mimic a simple version of fmt. It should read text on standard input, and write the words (a word is a string of characters terminated by a space or the end of a line) one by one to standard output. As many words as possible, separated by single characters, are to be on each output line. Each output line has a maximum width of 72 characters.

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3. You are provided with a file of coordinate data generated by a GPS ('Global Positioning System') device which has logged a journey. This takes the form of a text file in which each line consists of two decimal numbers, representing a map coordinate in kilometres, the first line being the start of the journey and the last line the end. Write a Perl script, taking one argument which is a filename, and outputs a message which is the calculated total length of the journey.

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