book

Perl Cookbook, 2nd Edition

by Tom Christiansen, Nathan Torkington

August 2003

Intermediate to advanced

964 pages

23h 24m

English

O'Reilly Media, Inc.

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A Note Regarding Supplemental Files
Foreword
Preface
What’s in This BookWhat’s New in This EditionPlatform NotesOther BooksConventions Used in This BookWe’d Like to Hear from YouAcknowledgments for the First EditionAcknowledgments for the Second Edition
1. Strings
Introduction1.1. Accessing Substrings1.2. Establishing a Default Value1.3. Exchanging Values Without Using Temporary Variables1.4. Converting Between Characters and Values1.5. Using Named Unicode Characters1.6. Processing a String One Character at a Time1.7. Reversing a String by Word or Character1.8. Treating Unicode Combined Characters as Single Characters1.9. Canonicalizing Strings with Unicode Combined Characters1.10. Treating a Unicode String as Octets1.11. Expanding and Compressing Tabs1.12. Expanding Variables in User Input1.13. Controlling Case1.14. Properly Capitalizing a Title or Headline1.15. Interpolating Functions and Expressions Within Strings1.16. Indenting Here Documents1.17. Reformatting Paragraphs1.18. Escaping Characters1.19. Trimming Blanks from the Ends of a String1.20. Parsing Comma-Separated Data1.21. Constant Variables1.22. Soundex Matching1.23. Program: fixstyle1.24. Program: psgrep
2. Numbers
Introduction2.1. Checking Whether a String Is a Valid Number2.2. Rounding Floating-Point Numbers2.3. Comparing Floating-Point Numbers2.4. Operating on a Series of Integers2.5. Working with Roman Numerals2.6. Generating Random Numbers2.7. Generating Repeatable Random Number Sequences2.8. Making Numbers Even More Random2.9. Generating Biased Random Numbers2.10. Doing Trigonometry in Degrees, Not Radians2.11. Calculating More Trigonometric Functions2.12. Taking Logarithms2.13. Multiplying Matrices2.14. Using Complex Numbers2.15. Converting Binary, Octal, and Hexadecimal Numbers2.16. Putting Commas in Numbers2.17. Printing Correct Plurals2.18. Program: Calculating Prime Factors
3. Dates and Times
Introduction3.1. Finding Today’s Date3.2. Converting DMYHMS to Epoch Seconds3.3. Converting Epoch Seconds to DMYHMS3.4. Adding to or Subtracting from a Date3.5. Difference of Two Dates3.6. Day in a Week/Month/Year or Week Number3.7. Parsing Dates and Times from Strings3.8. Printing a Date3.9. High-Resolution Timers3.10. Short Sleeps3.11. Program: hopdelta
4. Arrays
Introduction4.1. Specifying a List in Your Program4.2. Printing a List with Commas4.3. Changing Array Size4.4. Implementing a Sparse Array4.5. Iterating Over an Array4.6. Iterating Over an Array by Reference4.7. Extracting Unique Elements from a List4.8. Finding Elements in One Array but Not Another4.9. Computing Union, Intersection, or Difference of Unique Lists4.10. Appending One Array to Another4.11. Reversing an Array4.12. Processing Multiple Elements of an Array4.13. Finding the First List Element That Passes a Test4.14. Finding All Elements in an Array Matching Certain Criteria4.15. Sorting an Array Numerically4.16. Sorting a List by Computable Field4.17. Implementing a Circular List4.18. Randomizing an Array4.19. Program: words4.20. Program: permute
5. Hashes
Introduction5.1. Adding an Element to a Hash5.2. Testing for the Presence of a Key in a Hash5.3. Creating a Hash with Immutable Keys or Values5.4. Deleting from a Hash5.5. Traversing a Hash5.6. Printing a Hash5.7. Retrieving from a Hash in Insertion Order5.8. Hashes with Multiple Values per Key5.9. Inverting a Hash5.10. Sorting a Hash5.11. Merging Hashes5.12. Finding Common or Different Keys in Two Hashes5.13. Hashing References5.14. Presizing a Hash5.15. Finding the Most Common Anything5.16. Representing Relationships Between Data5.17. Program: dutree
6. Pattern Matching
Introduction6.1. Copying and Substituting Simultaneously6.2. Matching Letters6.3. Matching Words6.4. Commenting Regular Expressions6.5. Finding the Nth Occurrence of a Match6.6. Matching Within Multiple Lines6.7. Reading Records with a Separator6.8. Extracting a Range of Lines6.9. Matching Shell Globs as Regular Expressions6.10. Speeding Up Interpolated Matches6.11. Testing for a Valid Pattern6.12. Honoring Locale Settings in Regular Expressions6.13. Approximate Matching6.14. Matching from Where the Last Pattern Left Off6.15. Greedy and Non-Greedy Matches6.16. Detecting Doubled Words6.17. Matching Nested Patterns6.18. Expressing AND, OR, and NOT in a Single Pattern6.19. Matching a Valid Mail Address6.20. Matching Abbreviations6.21. Program: urlify6.22. Program: tcgrep6.23. Regular Expression Grab Bag
7. File Access
Introduction7.1. Opening a File7.2. Opening Files with Unusual Filenames7.3. Expanding Tildes in Filenames7.4. Making Perl Report Filenames in Error Messages7.5. Storing Filehandles into Variables7.6. Writing a Subroutine That Takes Filehandles as Built-ins Do7.7. Caching Open Output Filehandles7.8. Printing to Many Filehandles Simultaneously7.9. Opening and Closing File Descriptors by Number7.10. Copying Filehandles7.11. Creating Temporary Files7.12. Storing a File Inside Your Program Text7.13. Storing Multiple Files in the DATA Area7.14. Writing a Unix-Style Filter Program7.15. Modifying a File in Place with a Temporary File7.16. Modifying a File in Place with the -i Switch7.17. Modifying a File in Place Without a Temporary File7.18. Locking a File7.19. Flushing Output7.20. Doing Non-Blocking I/O7.21. Determining the Number of Unread Bytes7.22. Reading from Many Filehandles Without Blocking7.23. Reading an Entire Line Without Blocking7.24. Program: netlock7.25. Program: lockarea

8. File Contents
Introduction8.1. Reading Lines with Continuation Characters8.2. Counting Lines (or Paragraphs or Records) in a File8.3. Processing Every Word in a File8.4. Reading a File Backward by Line or Paragraph8.5. Trailing a Growing File8.6. Picking a Random Line from a File8.7. Randomizing All Lines8.8. Reading a Particular Line in a File8.9. Processing Variable-Length Text Fields8.10. Removing the Last Line of a File8.11. Processing Binary Files8.12. Using Random-Access I/O8.13. Updating a Random-Access File8.14. Reading a String from a Binary File8.15. Reading Fixed-Length Records8.16. Reading Configuration Files8.17. Testing a File for Trustworthiness8.18. Treating a File as an Array8.19. Setting the Default I/O Layers8.20. Reading or Writing Unicode from a Filehandle8.21. Converting Microsoft Text Files into Unicode8.22. Comparing the Contents of Two Files8.23. Pretending a String Is a File8.24. Program: tailwtmp8.25. Program: tctee8.26. Program: laston8.27. Program: Flat File Indexes
9. Directories
Introduction9.1. Getting and Setting Timestamps9.2. Deleting a File9.3. Copying or Moving a File9.4. Recognizing Two Names for the Same File9.5. Processing All Files in a Directory9.6. Globbing, or Getting a List of Filenames Matching a Pattern9.7. Processing All Files in a Directory Recursively9.8. Removing a Directory and Its Contents9.9. Renaming Files9.10. Splitting a Filename into Its Component Parts9.11. Working with Symbolic File Permissions Instead of Octal Values9.12. Program: symirror9.13. Program: lst
10. Subroutines
Introduction10.1. Accessing Subroutine Arguments10.2. Making Variables Private to a Function10.3. Creating Persistent Private Variables10.4. Determining Current Function Name10.5. Passing Arrays and Hashes by Reference10.6. Detecting Return Context10.7. Passing by Named Parameter10.8. Skipping Selected Return Values10.9. Returning More Than One Array or Hash10.10. Returning Failure10.11. Prototyping Functions10.12. Handling Exceptions10.13. Saving Global Values10.14. Redefining a Function10.15. Trapping Undefined Function Calls with AUTOLOAD10.16. Nesting Subroutines10.17. Writing a Switch Statement10.18. Program: Sorting Your Mail
11. References and Records
Introduction11.1. Taking References to Arrays11.2. Making Hashes of Arrays11.3. Taking References to Hashes11.4. Taking References to Functions11.5. Taking References to Scalars11.6. Creating Arrays of Scalar References11.7. Using Closures Instead of Objects11.8. Creating References to Methods11.9. Constructing Records11.10. Reading and Writing Hash Records to Text Files11.11. Printing Data Structures11.12. Copying Data Structures11.13. Storing Data Structures to Disk11.14. Transparently Persistent Data Structures11.15. Coping with Circular Data Structures Using Weak References11.16. Program: Outlines11.17. Program: Binary Trees
12. Packages, Libraries, and Modules
Introduction12.1. Defining a Module’s Interface12.2. Trapping Errors in require or use12.3. Delaying use Until Runtime12.4. Making Variables Private to a Module12.5. Making Functions Private to a Module12.6. Determining the Caller’s Package12.7. Automating Module Cleanup12.8. Keeping Your Own Module Directory12.9. Preparing a Module for Distribution12.10. Speeding Module Loading with SelfLoader12.11. Speeding Up Module Loading with Autoloader12.12. Overriding Built-in Functions12.13. Overriding a Built-in Function in All Packages12.14. Reporting Errors and Warnings Like Built-ins12.15. Customizing Warnings12.16. Referring to Packages Indirectly12.17. Using h2ph to Translate C #include Files12.18. Using h2xs to Make a Module with C Code12.19. Writing Extensions in C with Inline::C12.20. Documenting Your Module with Pod12.21. Building and Installing a CPAN Module12.22. Example: Module Template12.23. Program: Finding Versions and Descriptions of Installed Modules
13. Classes, Objects, and Ties
Introduction13.1. Constructing an Object13.2. Destroying an Object13.3. Managing Instance Data13.4. Managing Class Data13.5. Using Classes as Structs13.6. Cloning Constructors13.7. Copy Constructors13.8. Invoking Methods Indirectly13.9. Determining Subclass Membership13.10. Writing an Inheritable Class13.11. Accessing Overridden Methods13.12. Generating Attribute Methods Using AUTOLOAD13.13. Coping with Circular Data Structures Using Objects13.14. Overloading Operators13.15. Creating Magic Variables with tie
14. Database Access
Introduction14.1. Making and Using a DBM File14.2. Emptying a DBM File14.3. Converting Between DBM Files14.4. Merging DBM Files14.5. Sorting Large DBM Files14.6. Storing Complex Data in a DBM File14.7. Persistent Data14.8. Saving Query Results to Excel or CSV14.9. Executing an SQL Command Using DBI14.10. Escaping Quotes14.11. Dealing with Database Errors14.12. Repeating Queries Efficiently14.13. Building Queries Programmatically14.14. Finding the Number of Rows Returned by a Query14.15. Using Transactions14.16. Viewing Data One Page at a Time14.17. Querying a CSV File with SQL14.18. Using SQL Without a Database Server14.19. Program: ggh—Grep Netscape Global History
15. Interactivity
Introduction15.1. Parsing Program Arguments15.2. Testing Whether a Program Is Running Interactively15.3. Clearing the Screen15.4. Determining Terminal or Window Size15.5. Changing Text Color15.6. Reading Single Characters from the Keyboard15.7. Ringing the Terminal Bell15.8. Using POSIX termios15.9. Checking for Waiting Input15.10. Reading Passwords15.11. Editing Input15.12. Managing the Screen15.13. Controlling Another Program with Expect15.14. Creating Menus with Tk15.15. Creating Dialog Boxes with Tk15.16. Responding to Tk Resize Events15.17. Removing the DOS Shell Window with Windows Perl/Tk15.18. Graphing Data15.19. Thumbnailing Images15.20. Adding Text to an Image15.21. Program: Small termcap Program15.22. Program: tkshufflepod15.23. Program: graphbox
16. Process Management and Communication
Introduction16.1. Gathering Output from a Program16.2. Running Another Program16.3. Replacing the Current Program with a Different One16.4. Reading or Writing to Another Program16.5. Filtering Your Own Output16.6. Preprocessing Input16.7. Reading STDERR from a Program16.8. Controlling Input and Output of Another Program16.9. Controlling the Input, Output, and Error of Another Program16.10. Communicating Between Related Processes16.11. Making a Process Look Like a File with Named Pipes16.12. Sharing Variables in Different Processes16.13. Listing Available Signals16.14. Sending a Signal16.15. Installing a Signal Handler16.16. Temporarily Overriding a Signal Handler16.17. Writing a Signal Handler16.18. Catching Ctrl-C16.19. Avoiding Zombie Processes16.20. Blocking Signals16.21. Timing Out an Operation16.22. Turning Signals into Fatal Errors16.23. Program: sigrand
17. Sockets
Introduction17.1. Writing a TCP Client17.2. Writing a TCP Server17.3. Communicating over TCP17.4. Setting Up a UDP Client17.5. Setting Up a UDP Server17.6. Using Unix Domain Sockets17.7. Identifying the Other End of a Socket17.8. Finding Your Own Name and Address17.9. Closing a Socket After Forking17.10. Writing Bidirectional Clients17.11. Forking Servers17.12. Pre-Forking Servers17.13. Non-Forking Servers17.14. Multitasking Server with Threads17.15. Writing a Multitasking Server with POE17.16. Writing a Multihomed Server17.17. Making a Daemon Server17.18. Restarting a Server on Demand17.19. Managing Multiple Streams of Input17.20. Program: backsniff17.21. Program: fwdport
18. Internet Services
Introduction18.1. Simple DNS Lookups18.2. Being an FTP Client18.3. Sending Mail18.4. Reading and Posting Usenet News Messages18.5. Reading Mail with POP318.6. Simulating Telnet from a Program18.7. Pinging a Machine18.8. Accessing an LDAP Server18.9. Sending Attachments in Mail18.10. Extracting Attachments from Mail18.11. Writing an XML-RPC Server18.12. Writing an XML-RPC Client18.13. Writing a SOAP Server18.14. Writing a SOAP Client18.15. Program: rfrm18.16. Program: expn and vrfy
19. CGI Programming
Introduction19.1. Writing a CGI Script19.2. Redirecting Error Messages19.3. Fixing a 500 Server Error19.4. Writing a Safe CGI Program19.5. Executing Commands Without Shell Escapes19.6. Formatting Lists and Tables with HTML Shortcuts19.7. Redirecting to a Different Location19.8. Debugging the Raw HTTP Exchange19.9. Managing Cookies19.10. Creating Sticky Widgets19.11. Writing a Multiscreen CGI Script19.12. Saving a Form to a File or Mail Pipe19.13. Program: chemiserie
20. Web Automation
Introduction20.1. Fetching a URL from a Perl Script20.2. Automating Form Submission20.3. Extracting URLs20.4. Converting ASCII to HTML20.5. Converting HTML to ASCII20.6. Extracting or Removing HTML Tags20.7. Finding Stale Links20.8. Finding Fresh Links20.9. Using Templates to Generate HTML20.10. Mirroring Web Pages20.11. Creating a Robot20.12. Parsing a Web Server Log File20.13. Processing Server Logs20.14. Using Cookies20.15. Fetching Password-Protected Pages20.16. Fetching https:// Web Pages20.17. Resuming an HTTP GET20.18. Parsing HTML20.19. Extracting Table Data20.20. Program: htmlsub20.21. Program: hrefsub
21. mod_perl
Introduction21.1. Authenticating21.2. Setting Cookies21.3. Accessing Cookie Values21.4. Redirecting the Browser21.5. Interrogating Headers21.6. Accessing Form Parameters21.7. Receiving Uploaded Files21.8. Speeding Up Database Access21.9. Customizing Apache’s Logging21.10. Transparently Storing Information in URLs21.11. Communicating Between mod_perl and PHP21.12. Migrating from CGI to mod_perl21.13. Sharing Information Between Handlers21.14. Reloading Changed Modules21.15. Benchmarking a mod_perl Application21.16. Templating with HTML::Mason21.17. Templating with Template Toolkit
22. XML
Introduction22.1. Parsing XML into Data Structures22.2. Parsing XML into a DOM Tree22.3. Parsing XML into SAX Events22.4. Making Simple Changes to Elements or Text22.5. Validating XML22.6. Finding Elements and Text Within an XML Document22.7. Processing XML Stylesheet Transformations22.8. Processing Files Larger Than Available Memory22.9. Reading and Writing RSS Files22.10. Writing XML
About the Authors
Colophon
Copyright

Overview

Find a Perl programmer, and you'll find a copy of Perl Cookbook nearby. Perl Cookbook is a comprehensive collection of problems, solutions, and practical examples for anyone programming in Perl. The book contains hundreds of rigorously reviewed Perl "recipes" and thousands of examples ranging from brief one-liners to complete applications.The second edition of Perl Cookbook has been fully updated for Perl 5.8, with extensive changes for Unicode support, I/O layers, mod_perl, and new technologies that have emerged since the previous edition of the book. Recipes have been updated to include the latest modules. New recipes have been added to every chapter of the book, and some chapters have almost doubled in size.Covered topic areas include:

Manipulating strings, numbers, dates, arrays, and hashes
Pattern matching and text substitutions
References, data structures, objects, and classes
Signals and exceptions
Screen addressing, menus, and graphical applications
Managing other processes
Writing secure scripts
Client-server programming
Internet applications programming with mail, news, ftp, and telnet
CGI and mod_perl programming
Web programming

Since its first release in 1998, Perl Cookbook has earned its place in the libraries of serious Perl users of all levels of expertise by providing practical answers, code examples, and mini-tutorials addressing the challenges that programmers face. Now the second edition of this bestselling book is ready to earn its place among the ranks of favorite Perl books as well.Whether you're a novice or veteran Perl programmer, you'll find Perl Cookbook, 2nd Edition to be one of the most useful books on Perl available. Its comfortable discussion style and accurate attention to detail cover just about any topic you'd want to know about. You can get by without having this book in your library, but once you've tried a few of the recipes, you won't want to.

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