Perl Programming with Web Development

Perl Versions

The course covers Perl 5 and has been taught to users on: Unix, Linux & MS Windows. The course has been updated to Perl 5.16.

Preparing to Learn Perl

• About This Course
• What is Perl?
• Perl History
• Perl the Language
• Perl Programming Environment
• Running Perl Programs
• Running Perl Programs on Unix
• Running Perl Programs on Windows
• Very Basic Syntax
• Getting Perl to Help You
• A Sample Program
• Online Help

Perl: the Absolute Minimum

• Enough to Get Started
• A module designed for complete beginners
• The print Command
• Variables
• Scalars — Numbers and Strings
• Literal Numbers
• User Defined Constants
• Literal Strings
• Interpolation into Strings
• Assignment
• Truth in Perl
• Comparison Operators
• Conditional Tests
• Comparing Values
• A Popular Coding Error
• Smart Matching with ~~
• Alternative Tests
• Multiple Tests
• Switch Statements — given/when
• More on given for Loops while Loops unless and until use feature & use version #

Arrays and Hashes

• Arrays and Hashes
• Lists
• Writing Lists
• Arrays — for Storing Lists
• Using Lists and Arrays
• Iterating Over Lists
• Using foreach
• The push Function
• Indexing into Arrays
• Hashes
• Fat comma and hashes
• Arrays: fat comma and hash initialising
• Accessing Elements of a Hash
• Hash Example
• Iterating Over Hashes
• Iterating Over Hashes — Example
• Size of Arrays and Hashes

Perl: Input and Functions

• Simple Input
• Providing Standard Input
• Input Example
• Opening Files
• Reading and Writing Files
• Subroutines
• Subroutine Parameters
• Subroutine Parameters — Other Ways
• Calling Subroutines
• Calling Subroutines Without Arguments
• Returning Values from Subroutines
• Function Miscellany
• Persistent Variables

Text Manipulation with Regular Expressions

• Regular Expressions
• Other Metacharacters
• Regular Expression Examples
• Alternation and Grouping
• Built-in Character Classes
• Built-in Character Class Examples
• Matching Strings
• Matching the Default Variable
• Case-Sensitivity and Matching
• Capturing
• Regular Expression Examples
• Substitution
• Global Substitutions

Perl: Operators and Loops

• Concatenating Strings
• Fancy Assignment
• Assignment Shortcuts
• The Yada Yada Statement
• Autoincrement and Autodecrement
• Complex Conditions
• Short-Circuit Operators
• The Conditional Operator (Ternary Operator)
• Logical Defined-Or //
• Bitwise Operators
• Operator Precedence and Associativity; Sequence Points
• Operator Precedence and Associativity
• Undefined Values
• Overview of Flow Control
• Statement Modifiers
• Flow Control with or
• Flow Control with and
• More Loops
• Loop Control — next & last
• Example of next and last Statement redo in loops

Perl: Beyond the Basics

• Quoting Mechanisms
• Disambiguating Interpolation
• Different Quote Symbols q, qq, s///, and m//
• Quoting Lists
• Quoting Really Big Strings
• Changing Between Case
• Splitting Strings into Lists
• Joining Elements of Lists
• Filtering Lists with map
• Combining map and join
• Splitting, Mapping and Rejoining
• Using map to Initialise a Hash
• The sort Function
• Custom Sort Orders
• The grep function
• The Importance of Context
• Arrays in Different Contexts
• File Input in Different Contexts
• Difference Between .. & ... Operators
• Functions in Different Contexts
• Providing the Right Context
• Context Pitfalls
• Boolean Context void Context
• Special Variables
• Examples of Special Variables
• More Special Variables
• Input and Output Special Variables
• Scope
• Localizing Special Variables
• Using Command-Line Arguments
• Options Processing

Complex Data Structures & References

• Limits of Lists
• Nesting Arrays
• References in Arrays
• Dereferencing Array References
• Accessing a Particular Element of an Array Reference
• Arrays of Arrays
• The Data::Dumper
• Flexibility of Nesting Arrays
• Array References are Scalars
• Array Dereferencing Syntax
• Using the Arrow Operator
• Creating a Reference to a Named Array
• Passing Multiple Arrays to Functions
• Returning Multiple Arrays from Functions
• Hashes of Arrays
• Hash References
• Complex Data Structures
• Arrays of Hashes
• Hashes of Hashes
• Code References
• Invoking Code References
• Dispatch Tables

Finding Out More for Yourself

• So Far
• Perl is Big
• Look Things Up
• Main Perl Documentation
• Perl Doc Taxonomy
• Functions
• FAQs
• Reading the FAQs
• Searching FAQs
• The Perl Cookbook
• Other Perl Books
• Perl Websites
• Knowing What to Look for

Using Perl Modules from CPAN

• Perl Modules
• Using Modules
• Standard Modules
• CPAN Modules
• Why Effective Perl Programmers are Efficient CPAN Users
• Finding Modules on CPAN
• Installing Modules
• The cpan Command
• Finding Installed Modules
• Writing Perl Modules
• Perl Module Boilerplate
• Perl Module Boilerplate Explained
• Defining Functions in Modules
• Exporting Functions
• Exporting Functions - II
• Module Variables
• The Exporter
• Module Initialization
• Versions POD Plain Old Documentation File::Copy File::Find Text::Wrap

Debugging Perl

• Bugs
• Avoiding Bugs
• Perl's Built-in Debugger
• Debugger Documentation
• Using the Debugger
• Debugger Commands
• Advanced Debugger Commands
• Other Debugger Functionality
• Graphical Debugging ptkdb DDD
• Komodo
• Shunning the Debugger
• Using warn for Debugging Carp Module
• Printing Nested Data Structures
• Using the Debugger as a Perl Shell
• Unix and Linux Specific Tools
• Run X-Windows on MS Windows for Perl on Unix/Linux

Command-Line Perl

• General Principles
• Quoting Command-Line Perl Programs
• Command-Line Perl
• Command-Line Perl Syntax
• Using Modules
• Using Perl as a Filter
• Looping Through Input with -n
• Transforming Input with -p
• Editing Files In-Place with -i
• Backing Up In-Place Edits
• Other Command-Line Flags
• Autosplit Mode
• Example: Locale-Aware Downcasing
• Example: grep in Perl
• Example: Unix-Epoch Times
• Example: Summing Input Lines
• Example: Selecting a Range of Lines
• Example: Find Emphasised HTML Words
• Example: Printing Unique Input Words

A Whistle-Stop Tour of the World of Perl

• Built-in Functions
• General String Manipulation
• Extracting Bits of Strings
• Changing the Case of Letters
• Converting Between Strings and Numbers
• Mathematical Operations
• Formatted Strings
• Handling Binary Data
• General List Manipulation
• Adding and Removing from Arrays
• File-System Functions
• Idiomatic Perl Programming
• Handy Tricks with Variables
• Removing Duplicates
• Formatting Text
• Sending Email
• Sending Email — Unix-Specific

Perl Style

• Style Issues
• Indentation
• Identifier Naming
• Naming Variables
• Naming Functions
• Global Variables
• Using $_ for Readability
• High-Level Comments
• Low-Level Comments
• Parentheses
• Quoting
• Program Logic
• Structuring Data
• Modelling the World
• Object Orientation
• Style Resources

Handling Databases with Perl

• Interacting with SQL Databases Using Perl
• Using DBI
• Opening a Connection with DBI
• Example Query
• Running a Query
• Retrieving Records from SELECT
• Retrieving a Single Record
• Retrieving All the Records at Once
• Queries Which Don't Return Records
• SQL Injection Attacks
• Placeholders and Bind Values
• Two Last Notes
• Using ODBC
• Opening a Connection
• Executing Queries
• Fetching Records
• Reading Values from Records
• Other ODBC Methods
• Database Related Modules
• Tieing Hashes to Files
• Sample Database

Advanced File Processing

• Opening Files
• File open modes
• Alternative File-Opening Syntaxes
• Predefined File Handles
• Redirection-Style File Opening
• Input and Output
• Controlling Output Formatting
• Controlling Input Formatting
• Reading Paragraphs
• Reading a Whole File
• Reading Fixed-Sized Blocks
• The Flip-Flop Operator
• Handling Binary Files
• Output from Multiple Processes
• Examining Directories
• Examining File Metadata
• File Test Operators
• Symbolic Links
• File Locks
• Locking Files with flock

System Interaction

• Connecting to Other Programs
• Unsafe Pipes
• Using IO::Pipe
• Grabbing a Programs Output
• Other Ways to Run Programs

Perl Security Issues

• Writing Secure Perl
• Taint Checking
• Using Taint Checking
• Dangerous Environment Variables
• Input from Files
• Set-User-ID Perl Programs
• Permissions and Users

Introduction to CGI Programming

• What is CGI?
• A Simple CGI Program
• Running CGI Programs on a Web Server
• Running CGI Programs on Apache
• Running CGI Programs on Microsofts IIS
• Web pages with User Input
• Form Submission & CGI Parameters
• Parsing CGI Parameters with CGI::Lite
• Using Here-Docs
• Queries Using the GET Method
• GET Query Syntax
• Limitations of the GET Method
• POST Queries
• Limitations of the POST Method
• HTML Forms
• Checkbox Controls
• Radio Button Controls
• Submit Button Controls
• Submit Image Controls
• Creating Hyperlinks
• URL Encoding
• Debugging CGI Programs
• Better Error Messages with CGI::Carp
• Displaying Messages in the Browser
• Running CGI Programs at the Command Line
• A Debugging Checklist for CGI Programs
• The CGI Module

Further CGI Programming

• More CGI Issues
• Accessing HTTP Information
• HTTP Information About the Current Page
• Serving Non-HTML Content
• Generating Non-HTML Content
• Client Redirection
• HTTP Status Codes
• Status Codes with Redirection
• Sending Redirection Status Codes
• Maintaining State Across Requests
• Maintaining State with CGI Parameters
• Cookies
• Setting Cookies
• Parsing Cookies
• Using Cookies and CGI Parameters
• Session Handling
• Security of Session IDs
• Generating a Secure Session ID
• Propagating Session IDs
• Sessions Done Easily
• Example of Session Store
• File Upload Forms
• File Upload HTML
• Receiving Uploaded Files
• File Upload Denial-of-Service Issues
• Limitations of CGI
• Alternatives to CGI

Creating Web-Pages with HTML::Template

• Creating Web-Pages
• Using the CGI Module to Produce Web-Pages
• Embedding Perl in HTML
• Achieving Separation
• A Simple HTML::Template Template
• Advantages of HTML::Template
• HTML Character Entities
• Producing Lists
• Conditionals
• Complex Conditionals
• Nesting Structures
• Complex Loop Formatting
• Loop Context Variables
• Including Other Templates
• Deploying HTML::Template
• Flexibility of Using HTML::Template
• Flexibility of Loops
• Changing Templates Used with a Program
• Optional Parameters
• Permitting Optional Parameters
• Finding Out More
• Using HTML::Template
• One Final Point

Creating Web-Pages with HTML::Mason

• Why HTML::Mason ?
• Configuring Apache
• Apache: .mason Files Only
• Mason: Big Picture
• Mason: Concepts
• Escaping Values
• Conditional Values
• Scripted Values
• Formatting HTML
• Calling in Other Components
• Perl Code to Call in Components
• Named Blocks <%perl> Blocks <%args> Blocks
• Example <%args> Block
• Using the <%args> Block
• Component Arguments in %ARGS and @_
• Component Arguments Via GET and POST
• Example Decoding Arguments Via GET and POST <%once> Blocks <%init> Blocks <%cleanup> Blocks <%text> Blocks <%doc> Blocks <%flags> Blocks <%attr> Blocks
• Autohandlers
• Autohandler Example
• Autohandlers for Initialisation
• Autohandler to Open a Database
• Dhandlers
• Finding and Executing a Dhandler
• Comments in Mason

Web Security Issues

• CGI Scripts and Security
• Putting User Input on the Web
• Guest Book Example
• Interpolation of Dangerous Strings
• Removing Special Characters
• Dangerous Strings as File names
• Unsafe Pipes
• Using IO::Pipe
• The Poisoned NUL Character
• File Uploads
• Safe Communication with Databases
• Permissions for CGI Programs

References

• Interesting Web Links