Perl Cookbook, 2nd Edition by Christiansen, Tom -- Read -- Imperial Library of Trantor

Index

Perl Cookbook, 2nd Edition A Note Regarding Supplemental Files Foreword Preface

What’s in This Book What’s New in This Edition Platform Notes Other Books Conventions Used in This Book We’d Like to Hear from You Acknowledgments for the First Edition Acknowledgments for the Second Edition

1. Strings

Introduction 1.1. Accessing Substrings 1.2. Establishing a Default Value 1.3. Exchanging Values Without Using Temporary Variables 1.4. Converting Between Characters and Values 1.5. Using Named Unicode Characters 1.6. Processing a String One Character at a Time 1.7. Reversing a String by Word or Character 1.8. Treating Unicode Combined Characters as Single Characters 1.9. Canonicalizing Strings with Unicode Combined Characters 1.10. Treating a Unicode String as Octets 1.11. Expanding and Compressing Tabs 1.12. Expanding Variables in User Input 1.13. Controlling Case 1.14. Properly Capitalizing a Title or Headline 1.15. Interpolating Functions and Expressions Within Strings 1.16. Indenting Here Documents 1.17. Reformatting Paragraphs 1.18. Escaping Characters 1.19. Trimming Blanks from the Ends of a String 1.20. Parsing Comma-Separated Data 1.21. Constant Variables 1.22. Soundex Matching 1.23. Program: fixstyle 1.24. Program: psgrep

2. Numbers

Introduction 2.1. Checking Whether a String Is a Valid Number 2.2. Rounding Floating-Point Numbers 2.3. Comparing Floating-Point Numbers 2.4. Operating on a Series of Integers 2.5. Working with Roman Numerals 2.6. Generating Random Numbers 2.7. Generating Repeatable Random Number Sequences 2.8. Making Numbers Even More Random 2.9. Generating Biased Random Numbers 2.10. Doing Trigonometry in Degrees, Not Radians 2.11. Calculating More Trigonometric Functions 2.12. Taking Logarithms 2.13. Multiplying Matrices 2.14. Using Complex Numbers 2.15. Converting Binary, Octal, and Hexadecimal Numbers 2.16. Putting Commas in Numbers 2.17. Printing Correct Plurals 2.18. Program: Calculating Prime Factors

3. Dates and Times

Introduction 3.1. Finding Today’s Date 3.2. Converting DMYHMS to Epoch Seconds 3.3. Converting Epoch Seconds to DMYHMS 3.4. Adding to or Subtracting from a Date 3.5. Difference of Two Dates 3.6. Day in a Week/Month/Year or Week Number 3.7. Parsing Dates and Times from Strings 3.8. Printing a Date 3.9. High-Resolution Timers 3.10. Short Sleeps 3.11. Program: hopdelta

4. Arrays

Introduction 4.1. Specifying a List in Your Program 4.2. Printing a List with Commas 4.3. Changing Array Size 4.4. Implementing a Sparse Array 4.5. Iterating Over an Array 4.6. Iterating Over an Array by Reference 4.7. Extracting Unique Elements from a List 4.8. Finding Elements in One Array but Not Another 4.9. Computing Union, Intersection, or Difference of Unique Lists 4.10. Appending One Array to Another 4.11. Reversing an Array 4.12. Processing Multiple Elements of an Array 4.13. Finding the First List Element That Passes a Test 4.14. Finding All Elements in an Array Matching Certain Criteria 4.15. Sorting an Array Numerically 4.16. Sorting a List by Computable Field 4.17. Implementing a Circular List 4.18. Randomizing an Array 4.19. Program: words 4.20. Program: permute

5. Hashes

Introduction 5.1. Adding an Element to a Hash 5.2. Testing for the Presence of a Key in a Hash 5.3. Creating a Hash with Immutable Keys or Values 5.4. Deleting from a Hash 5.5. Traversing a Hash 5.6. Printing a Hash 5.7. Retrieving from a Hash in Insertion Order 5.8. Hashes with Multiple Values per Key 5.9. Inverting a Hash 5.10. Sorting a Hash 5.11. Merging Hashes 5.12. Finding Common or Different Keys in Two Hashes 5.13. Hashing References 5.14. Presizing a Hash 5.15. Finding the Most Common Anything 5.16. Representing Relationships Between Data 5.17. Program: dutree

6. Pattern Matching

Introduction 6.1. Copying and Substituting Simultaneously 6.2. Matching Letters 6.3. Matching Words 6.4. Commenting Regular Expressions 6.5. Finding the Nth Occurrence of a Match 6.6. Matching Within Multiple Lines 6.7. Reading Records with a Separator 6.8. Extracting a Range of Lines 6.9. Matching Shell Globs as Regular Expressions 6.10. Speeding Up Interpolated Matches 6.11. Testing for a Valid Pattern 6.12. Honoring Locale Settings in Regular Expressions 6.13. Approximate Matching 6.14. Matching from Where the Last Pattern Left Off 6.15. Greedy and Non-Greedy Matches 6.16. Detecting Doubled Words 6.17. Matching Nested Patterns 6.18. Expressing AND, OR, and NOT in a Single Pattern 6.19. Matching a Valid Mail Address 6.20. Matching Abbreviations 6.21. Program: urlify 6.22. Program: tcgrep 6.23. Regular Expression Grab Bag

7. File Access

Introduction 7.1. Opening a File 7.2. Opening Files with Unusual Filenames 7.3. Expanding Tildes in Filenames 7.4. Making Perl Report Filenames in Error Messages 7.5. Storing Filehandles into Variables 7.6. Writing a Subroutine That Takes Filehandles as Built-ins Do 7.7. Caching Open Output Filehandles 7.8. Printing to Many Filehandles Simultaneously 7.9. Opening and Closing File Descriptors by Number 7.10. Copying Filehandles 7.11. Creating Temporary Files 7.12. Storing a File Inside Your Program Text 7.13. Storing Multiple Files in the DATA Area 7.14. Writing a Unix-Style Filter Program 7.15. Modifying a File in Place with a Temporary File 7.16. Modifying a File in Place with the -i Switch 7.17. Modifying a File in Place Without a Temporary File 7.18. Locking a File 7.19. Flushing Output 7.20. Doing Non-Blocking I/O 7.21. Determining the Number of Unread Bytes 7.22. Reading from Many Filehandles Without Blocking 7.23. Reading an Entire Line Without Blocking 7.24. Program: netlock 7.25. Program: lockarea

8. File Contents

Introduction 8.1. Reading Lines with Continuation Characters 8.2. Counting Lines (or Paragraphs or Records) in a File 8.3. Processing Every Word in a File 8.4. Reading a File Backward by Line or Paragraph 8.5. Trailing a Growing File 8.6. Picking a Random Line from a File 8.7. Randomizing All Lines 8.8. Reading a Particular Line in a File 8.9. Processing Variable-Length Text Fields 8.10. Removing the Last Line of a File 8.11. Processing Binary Files 8.12. Using Random-Access I/O 8.13. Updating a Random-Access File 8.14. Reading a String from a Binary File 8.15. Reading Fixed-Length Records 8.16. Reading Configuration Files 8.17. Testing a File for Trustworthiness 8.18. Treating a File as an Array 8.19. Setting the Default I/O Layers 8.20. Reading or Writing Unicode from a Filehandle 8.21. Converting Microsoft Text Files into Unicode 8.22. Comparing the Contents of Two Files 8.23. Pretending a String Is a File 8.24. Program: tailwtmp 8.25. Program: tctee 8.26. Program: laston 8.27. Program: Flat File Indexes

9. Directories

Introduction 9.1. Getting and Setting Timestamps 9.2. Deleting a File 9.3. Copying or Moving a File 9.4. Recognizing Two Names for the Same File 9.5. Processing All Files in a Directory 9.6. Globbing, or Getting a List of Filenames Matching a Pattern 9.7. Processing All Files in a Directory Recursively 9.8. Removing a Directory and Its Contents 9.9. Renaming Files 9.10. Splitting a Filename into Its Component Parts 9.11. Working with Symbolic File Permissions Instead of Octal Values 9.12. Program: symirror 9.13. Program: lst

10. Subroutines

Introduction 10.1. Accessing Subroutine Arguments 10.2. Making Variables Private to a Function 10.3. Creating Persistent Private Variables 10.4. Determining Current Function Name 10.5. Passing Arrays and Hashes by Reference 10.6. Detecting Return Context 10.7. Passing by Named Parameter 10.8. Skipping Selected Return Values 10.9. Returning More Than One Array or Hash 10.10. Returning Failure 10.11. Prototyping Functions 10.12. Handling Exceptions 10.13. Saving Global Values 10.14. Redefining a Function 10.15. Trapping Undefined Function Calls with AUTOLOAD 10.16. Nesting Subroutines 10.17. Writing a Switch Statement 10.18. Program: Sorting Your Mail

11. References and Records

Introduction 11.1. Taking References to Arrays 11.2. Making Hashes of Arrays 11.3. Taking References to Hashes 11.4. Taking References to Functions 11.5. Taking References to Scalars 11.6. Creating Arrays of Scalar References 11.7. Using Closures Instead of Objects 11.8. Creating References to Methods 11.9. Constructing Records 11.10. Reading and Writing Hash Records to Text Files 11.11. Printing Data Structures 11.12. Copying Data Structures 11.13. Storing Data Structures to Disk 11.14. Transparently Persistent Data Structures 11.15. Coping with Circular Data Structures Using Weak References 11.16. Program: Outlines 11.17. Program: Binary Trees

12. Packages, Libraries, and Modules

Introduction 12.1. Defining a Module’s Interface 12.2. Trapping Errors in require or use 12.3. Delaying use Until Runtime 12.4. Making Variables Private to a Module 12.5. Making Functions Private to a Module 12.6. Determining the Caller’s Package 12.7. Automating Module Cleanup 12.8. Keeping Your Own Module Directory 12.9. Preparing a Module for Distribution 12.10. Speeding Module Loading with SelfLoader 12.11. Speeding Up Module Loading with Autoloader 12.12. Overriding Built-in Functions 12.13. Overriding a Built-in Function in All Packages 12.14. Reporting Errors and Warnings Like Built-ins 12.15. Customizing Warnings 12.16. Referring to Packages Indirectly 12.17. Using h2ph to Translate C #include Files 12.18. Using h2xs to Make a Module with C Code 12.19. Writing Extensions in C with Inline::C 12.20. Documenting Your Module with Pod 12.21. Building and Installing a CPAN Module 12.22. Example: Module Template 12.23. Program: Finding Versions and Descriptions of Installed Modules

13. Classes, Objects, and Ties

Introduction 13.1. Constructing an Object 13.2. Destroying an Object 13.3. Managing Instance Data 13.4. Managing Class Data 13.5. Using Classes as Structs 13.6. Cloning Constructors 13.7. Copy Constructors 13.8. Invoking Methods Indirectly 13.9. Determining Subclass Membership 13.10. Writing an Inheritable Class 13.11. Accessing Overridden Methods 13.12. Generating Attribute Methods Using AUTOLOAD 13.13. Coping with Circular Data Structures Using Objects 13.14. Overloading Operators 13.15. Creating Magic Variables with tie

14. Database Access

Introduction 14.1. Making and Using a DBM File 14.2. Emptying a DBM File 14.3. Converting Between DBM Files 14.4. Merging DBM Files 14.5. Sorting Large DBM Files 14.6. Storing Complex Data in a DBM File 14.7. Persistent Data 14.8. Saving Query Results to Excel or CSV 14.9. Executing an SQL Command Using DBI 14.10. Escaping Quotes 14.11. Dealing with Database Errors 14.12. Repeating Queries Efficiently 14.13. Building Queries Programmatically 14.14. Finding the Number of Rows Returned by a Query 14.15. Using Transactions 14.16. Viewing Data One Page at a Time 14.17. Querying a CSV File with SQL 14.18. Using SQL Without a Database Server 14.19. Program: ggh—Grep Netscape Global History

15. Interactivity

Introduction 15.1. Parsing Program Arguments 15.2. Testing Whether a Program Is Running Interactively 15.3. Clearing the Screen 15.4. Determining Terminal or Window Size 15.5. Changing Text Color 15.6. Reading Single Characters from the Keyboard 15.7. Ringing the Terminal Bell 15.8. Using POSIX termios 15.9. Checking for Waiting Input 15.10. Reading Passwords 15.11. Editing Input 15.12. Managing the Screen 15.13. Controlling Another Program with Expect 15.14. Creating Menus with Tk 15.15. Creating Dialog Boxes with Tk 15.16. Responding to Tk Resize Events 15.17. Removing the DOS Shell Window with Windows Perl/Tk 15.18. Graphing Data 15.19. Thumbnailing Images 15.20. Adding Text to an Image 15.21. Program: Small termcap Program 15.22. Program: tkshufflepod 15.23. Program: graphbox

16. Process Management and Communication

Introduction 16.1. Gathering Output from a Program 16.2. Running Another Program 16.3. Replacing the Current Program with a Different One 16.4. Reading or Writing to Another Program 16.5. Filtering Your Own Output 16.6. Preprocessing Input 16.7. Reading STDERR from a Program 16.8. Controlling Input and Output of Another Program 16.9. Controlling the Input, Output, and Error of Another Program 16.10. Communicating Between Related Processes 16.11. Making a Process Look Like a File with Named Pipes 16.12. Sharing Variables in Different Processes 16.13. Listing Available Signals 16.14. Sending a Signal 16.15. Installing a Signal Handler 16.16. Temporarily Overriding a Signal Handler 16.17. Writing a Signal Handler 16.18. Catching Ctrl-C 16.19. Avoiding Zombie Processes 16.20. Blocking Signals 16.21. Timing Out an Operation 16.22. Turning Signals into Fatal Errors 16.23. Program: sigrand

17. Sockets

Introduction 17.1. Writing a TCP Client 17.2. Writing a TCP Server 17.3. Communicating over TCP 17.4. Setting Up a UDP Client 17.5. Setting Up a UDP Server 17.6. Using Unix Domain Sockets 17.7. Identifying the Other End of a Socket 17.8. Finding Your Own Name and Address 17.9. Closing a Socket After Forking 17.10. Writing Bidirectional Clients 17.11. Forking Servers 17.12. Pre-Forking Servers 17.13. Non-Forking Servers 17.14. Multitasking Server with Threads 17.15. Writing a Multitasking Server with POE 17.16. Writing a Multihomed Server 17.17. Making a Daemon Server 17.18. Restarting a Server on Demand 17.19. Managing Multiple Streams of Input 17.20. Program: backsniff 17.21. Program: fwdport

18. Internet Services

Introduction 18.1. Simple DNS Lookups 18.2. Being an FTP Client 18.3. Sending Mail 18.4. Reading and Posting Usenet News Messages 18.5. Reading Mail with POP3 18.6. Simulating Telnet from a Program 18.7. Pinging a Machine 18.8. Accessing an LDAP Server 18.9. Sending Attachments in Mail 18.10. Extracting Attachments from Mail 18.11. Writing an XML-RPC Server 18.12. Writing an XML-RPC Client 18.13. Writing a SOAP Server 18.14. Writing a SOAP Client 18.15. Program: rfrm 18.16. Program: expn and vrfy

19. CGI Programming

Introduction 19.1. Writing a CGI Script 19.2. Redirecting Error Messages 19.3. Fixing a 500 Server Error 19.4. Writing a Safe CGI Program 19.5. Executing Commands Without Shell Escapes 19.6. Formatting Lists and Tables with HTML Shortcuts 19.7. Redirecting to a Different Location 19.8. Debugging the Raw HTTP Exchange 19.9. Managing Cookies 19.10. Creating Sticky Widgets 19.11. Writing a Multiscreen CGI Script 19.12. Saving a Form to a File or Mail Pipe 19.13. Program: chemiserie

20. Web Automation

Introduction 20.1. Fetching a URL from a Perl Script 20.2. Automating Form Submission 20.3. Extracting URLs 20.4. Converting ASCII to HTML 20.5. Converting HTML to ASCII 20.6. Extracting or Removing HTML Tags 20.7. Finding Stale Links 20.8. Finding Fresh Links 20.9. Using Templates to Generate HTML 20.10. Mirroring Web Pages 20.11. Creating a Robot 20.12. Parsing a Web Server Log File 20.13. Processing Server Logs 20.14. Using Cookies 20.15. Fetching Password-Protected Pages 20.16. Fetching https:// Web Pages 20.17. Resuming an HTTP GET 20.18. Parsing HTML 20.19. Extracting Table Data 20.20. Program: htmlsub 20.21. Program: hrefsub

21. mod_perl

Introduction 21.1. Authenticating 21.2. Setting Cookies 21.3. Accessing Cookie Values 21.4. Redirecting the Browser 21.5. Interrogating Headers 21.6. Accessing Form Parameters 21.7. Receiving Uploaded Files 21.8. Speeding Up Database Access 21.9. Customizing Apache’s Logging 21.10. Transparently Storing Information in URLs 21.11. Communicating Between mod_perl and PHP 21.12. Migrating from CGI to mod_perl 21.13. Sharing Information Between Handlers 21.14. Reloading Changed Modules 21.15. Benchmarking a mod_perl Application 21.16. Templating with HTML::Mason 21.17. Templating with Template Toolkit

22. XML

Introduction 22.1. Parsing XML into Data Structures 22.2. Parsing XML into a DOM Tree 22.3. Parsing XML into SAX Events 22.4. Making Simple Changes to Elements or Text 22.5. Validating XML 22.6. Finding Elements and Text Within an XML Document 22.7. Processing XML Stylesheet Transformations 22.8. Processing Files Larger Than Available Memory 22.9. Reading and Writing RSS Files 22.10. Writing XML

About the Authors Colophon Copyright

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