Tutorial: Perl tutorial

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Perl tutorial

Chapter 1. Strings Introduction Recipe 1.1 Accessing Substrings Recipe 1.2 Establishing a Default Value Recipe 1.3 Exchanging Values Without Using Temporary Variables Recipe 1.4 Converting Between Characters and Values Recipe 1.5 Using Named Unicode Characters Recipe 1.6 Processing a String One Character at a Time Recipe 1.7 Reversing a String by Word or Character Recipe 1.8 Treating Unicode Combined Characters as Single Characters Recipe 1.9 Canonicalizing Strings with Unicode Combined Characters Recipe 1.10 Treating a Unicode String as Octets Recipe 1.11 Expanding and Compressing Tabs Recipe 1.12 Expanding Variables in User Input Recipe 1.13 Controlling Case Recipe 1.14 Properly Capitalizing a Title or Headline Recipe 1.15 Interpolating Functions and Expressions Within Strings Recipe 1.16 Indenting Here Documents Recipe 1.17 Reformatting Paragraphs Recipe 1.18 Escaping Characters Recipe 1.19 Trimming Blanks from the Ends of a String Recipe 1.20 Parsing Comma-Separated Data Recipe 1.21 Constant Variables Recipe 1.22 Soundex Matching Recipe 1.23 Program: fixstyle Recipe 1.24 Program: psgrep Chapter 2. Numbers Introduction Recipe 2.1 Checking Whether a String Is a Valid Number Recipe 2.2 Rounding Floating-Point Numbers Recipe 2.3 Comparing Floating-Point Numbers Recipe 2.4 Operating on a Series of Integers Recipe 2.5 Working with Roman Numerals Recipe 2.6 Generating Random Numbers Recipe 2.7 Generating Repeatable Random Number Sequences Recipe 2.8 Making Numbers Even More Random Recipe 2.9 Generating Biased Random Numbers Recipe 2.10 Doing Trigonometry in Degrees, Not Radians Recipe 2.11 Calculating More Trigonometric Functions Recipe 2.12 Taking Logarithms Recipe 2.13 Multiplying Matrices Recipe 2.14 Using Complex Numbers Recipe 2.15 Converting Binary, Octal, and Hexadecimal Numbers Recipe 2.16 Putting Commas in Numbers Recipe 2.17 Printing Correct Plurals Recipe 2.18 Program: Calculating Prime Factors Chapter 3. Dates and Times Introduction Recipe 3.1 Finding Today's Date Recipe 3.2 Converting DMYHMS to Epoch Seconds Recipe 3.3 Converting Epoch Seconds to DMYHMS Recipe 3.4 Adding to or Subtracting from a Date Recipe 3.5 Difference of Two Dates Recipe 3.6 Day in a Week/Month/Year or Week Number Recipe 3.7 Parsing Dates and Times from Strings Recipe 3.8 Printing a Date Recipe 3.9 High-Resolution Timers Recipe 3.10 Short Sleeps Recipe 3.11 Program: hopdelta Chapter 4. Arrays Introduction Recipe 4.1 Specifying a List in Your Program Recipe 4.2 Printing a List with Commas Recipe 4.3 Changing Array Size Recipe 4.4 Implementing a Sparse Array Recipe 4.5 Iterating Over an Array Recipe 4.6 Iterating Over an Array by Reference Recipe 4.7 Extracting Unique Elements from a List Recipe 4.8 Finding Elements in One Array but Not Another Recipe 4.9 Computing Union, Intersection, or Difference of Unique Lists Recipe 4.10 Appending One Array to Another Recipe 4.11 Reversing an Array Recipe 4.12 Processing Multiple Elements of an Array Recipe 4.13 Finding the First List Element That Passes a Test Recipe 4.14 Finding All Elements in an Array Matching Certain Criteria Recipe 4.15 Sorting an Array Numerically Recipe 4.16 Sorting a List by Computable Field Recipe 4.17 Implementing a Circular List Recipe 4.18 Randomizing an Array Recipe 4.19 Program: words Recipe 4.20 Program: permute Chapter 5. Hashes Introduction Recipe 5.1 Adding an Element to a Hash Recipe 5.2 Testing for the Presence of a Key in a Hash Recipe 5.3 Creating a Hash with Immutable Keys or Values Recipe 5.4 Deleting from a Hash Recipe 5.5 Traversing a Hash Recipe 5.6 Printing a Hash Recipe 5.7 Retrieving from a Hash in Insertion Order Recipe 5.8 Hashes with Multiple Values per Key Recipe 5.9 Inverting a Hash Recipe 5.10 Sorting a Hash Recipe 5.11 Merging Hashes Recipe 5.12 Finding Common or Different Keys in Two Hashes Recipe 5.13 Hashing References Recipe 5.14 Presizing a Hash Recipe 5.15 Finding the Most Common Anything Recipe 5.16 Representing Relationships Between Data Recipe 5.17 Program: dutree Chapter 6. Pattern Matching Introduction Recipe 6.1 Copying and Substituting Simultaneously Recipe 6.2 Matching Letters Recipe 6.3 Matching Words Recipe 6.4 Commenting Regular Expressions Recipe 6.5 Finding the Nth Occurrence of a Match Recipe 6.6 Matching Within Multiple Lines Recipe 6.7 Reading Records with a Separator Recipe 6.8 Extracting a Range of Lines Recipe 6.9 Matching Shell Globs as Regular Expressions Recipe 6.10 Speeding Up Interpolated Matches Recipe 6.11 Testing for a Valid Pattern Recipe 6.12 Honoring Locale Settings in Regular Expressions Recipe 6.13 Approximate Matching Recipe 6.14 Matching from Where the Last Pattern Left Off Recipe 6.15 Greedy and Non-Greedy Matches Recipe 6.16 Detecting Doubled Words Recipe 6.17 Matching Nested Patterns Recipe 6.18 Expressing AND, OR, and NOT in a Single Pattern Recipe 6.19 Matching a Valid Mail Address Recipe 6.20 Matching Abbreviations Recipe 6.21 Program: urlify Recipe 6.22 Program: tcgrep Recipe 6.23 Regular Expression Grab Bag Chapter 7. File Access Introduction Recipe 7.1 Opening a File Recipe 7.2 Opening Files with Unusual Filenames Recipe 7.3 Expanding Tildes in Filenames Recipe 7.4 Making Perl Report Filenames in Error Messages Recipe 7.5 Storing Filehandles into Variables Recipe 7.6 Writing a Subroutine That Takes Filehandles as Built-ins Do Recipe 7.7 Caching Open Output Filehandles Recipe 7.8 Printing to Many Filehandles Simultaneously Recipe 7.9 Opening and Closing File Descriptors by Number Recipe 7.10 Copying Filehandles Recipe 7.11 Creating Temporary Files Recipe 7.12 Storing a File Inside Your Program Text Recipe 7.13 Storing Multiple Files in the DATA Area Recipe 7.14 Writing a Unix-Style Filter Program Recipe 7.15 Modifying a File in Place with a Temporary File Recipe 7.16 Modifying a File in Place with the -i Switch Recipe 7.17 Modifying a File in Place Without a Temporary File Recipe 7.18 Locking a File Recipe 7.19 Flushing Output Recipe 7.20 Doing Non-Blocking I/O Recipe 7.21 Determining the Number of Unread Bytes Recipe 7.22 Reading from Many Filehandles Without Blocking Recipe 7.23 Reading an Entire Line Without Blocking Recipe 7.24 Program: netlock Recipe 7.25 Program: lockarea Chapter 8. File Contents Introduction Recipe 8.1 Reading Lines with Continuation Characters Recipe 8.2 Counting Lines (or Paragraphs or Records) in a File Recipe 8.3 Processing Every Word in a File Recipe 8.4 Reading a File Backward by Line or Paragraph Recipe 8.5 Trailing a Growing File Recipe 8.6 Picking a Random Line from a File Recipe 8.7 Randomizing All Lines Recipe 8.8 Reading a Particular Line in a File Recipe 8.9 Processing Variable-Length Text Fields Recipe 8.10 Removing the Last Line of a File Recipe 8.11 Processing Binary Files Recipe 8.12 Using Random-Access I/O Recipe 8.13 Updating a Random-Access File Recipe 8.14 Reading a String from a Binary File Recipe 8.15 Reading Fixed-Length Records Recipe 8.16 Reading Configuration Files Recipe 8.17 Testing a File for Trustworthiness Recipe 8.18 Treating a File as an Array Recipe 8.19 Setting the Default I/O Layers Recipe 8.20 Reading or Writing Unicode from a Filehandle Recipe 8.21 Converting Microsoft Text Files into Unicode Recipe 8.22 Comparing the Contents of Two Files Recipe 8.23 Pretending a String Is a File Recipe 8.24 Program: tailwtmp Recipe 8.25 Program: tctee Recipe 8.26 Program: laston Recipe 8.27 Program: Flat File Indexes Chapter 9. Directories Introduction Recipe 9.1 Getting and Setting Timestamps Recipe 9.2 Deleting a File Recipe 9.3 Copying or Moving a File Recipe 9.4 Recognizing Two Names for the Same File Recipe 9.5 Processing All Files in a Directory Recipe 9.6 Globbing, or Getting a List of Filenames Matching a Pattern Recipe 9.7 Processing All Files in a Directory Recursively Recipe 9.8 Removing a Directory and Its Contents Recipe 9.9 Renaming Files Recipe 9.10 Splitting a Filename into Its Component Parts Recipe 9.11 Working with Symbolic File Permissions Instead of Octal Values Recipe 9.12 Program: symirror Recipe 9.13 Program: lst Chapter 10. Subroutines Introduction Recipe 10.1 Accessing Subroutine Arguments Recipe 10.2 Making Variables Private to a Function Recipe 10.3 Creating Persistent Private Variables Recipe 10.4 Determining Current Function Name Recipe 10.5 Passing Arrays and Hashes by Reference Recipe 10.6 Detecting Return Context Recipe 10.7 Passing by Named Parameter Recipe 10.8 Skipping Selected Return Values Recipe 10.9 Returning More Than One Array or Hash Recipe 10.10 Returning Failure Recipe 10.11 Prototyping Functions Recipe 10.12 Handling Exceptions Recipe 10.13 Saving Global Values Recipe 10.14 Redefining a Function Recipe 10.15 Trapping Undefined Function Calls with AUTOLOAD Recipe 10.16 Nesting Subroutines Recipe 10.17 Writing a Switch Statement Recipe 10.18 Program: Sorting Your Mail Chapter 11. References and Records Introduction Recipe 11.1 Taking References to Arrays Recipe 11.2 Making Hashes of Arrays Recipe 11.3 Taking References to Hashes Recipe 11.4 Taking References to Functions Recipe 11.5 Taking References to Scalars Recipe 11.6 Creating Arrays of Scalar References Recipe 11.7 Using Closures Instead of Objects Recipe 11.8 Creating References to Methods Recipe 11.9 Constructing Records Recipe 11.10 Reading and Writing Hash Records to Text Files Recipe 11.11 Printing Data Structures Recipe 11.12 Copying Data Structures Recipe 11.13 Storing Data Structures to Disk Recipe 11.14 Transparently Persistent Data Structures Recipe 11.15 Coping with Circular Data Structures Using Weak References Recipe 11.16 Program: Outlines Recipe 11.17 Program: Binary Trees Chapter 12. Packages, Libraries, and Modules Introduction Recipe 12.1 Defining a Module's Interface Recipe 12.2 Trapping Errors in require or use Recipe 12.3 Delaying use Until Runtime Recipe 12.4 Making Variables Private to a Module Recipe 12.5 Making Functions Private to a Module Recipe 12.6 Determining the Caller's Package Recipe 12.7 Automating Module Cleanup Recipe 12.8 Keeping Your Own Module Directory Recipe 12.9 Preparing a Module for Distribution Recipe 12.10 Speeding Module Loading with SelfLoader Recipe 12.11 Speeding Up Module Loading with Autoloader Recipe 12.12 Overriding Built-in Functions Recipe 12.13 Overriding a Built-in Function in All Packages Recipe 12.14 Reporting Errors and Warnings Like Built-ins Recipe 12.15 Customizing Warnings Recipe 12.16 Referring to Packages Indirectly Recipe 12.17 Using h2ph to Translate C #include Files Recipe 12.18 Using h2xs to Make a Module with C Code Recipe 12.19 Writing Extensions in C with Inline::C Recipe 12.20 Documenting Your Module with Pod Recipe 12.21 Building and Installing a CPAN Module Recipe 12.22 Example: Module Template Recipe 12.23 Program: Finding Versions and Descriptions of Installed Modules Chapter 13. Classes, Objects, and Ties Introduction Recipe 13.1 Constructing an Object Recipe 13.2 Destroying an Object Recipe 13.3 Managing Instance Data Recipe 13.4 Managing Class Data Recipe 13.5 Using Classes as Structs Recipe 13.6 Cloning Constructors Recipe 13.7 Copy Constructors Recipe 13.8 Invoking Methods Indirectly Recipe 13.9 Determining Subclass Membership Recipe 13.10 Writing an Inheritable Class Recipe 13.11 Accessing Overridden Methods Recipe 13.12 Generating Attribute Methods Using AUTOLOAD Recipe 13.13 Coping with Circular Data Structures Using Objects Recipe 13.14 Overloading Operators Recipe 13.15 Creating Magic Variables with tie Chapter 14. Database Access Introduction Recipe 14.1 Making and Using a DBM File Recipe 14.2 Emptying a DBM File Recipe 14.3 Converting Between DBM Files Recipe 14.4 Merging DBM Files Recipe 14.5 Sorting Large DBM Files Recipe 14.6 Storing Complex Data in a DBM File Recipe 14.7 Persistent Data Recipe 14.8 Saving Query Results to Excel or CSV Recipe 14.9 Executing an SQL Command Using DBI Recipe 14.10 Escaping Quotes Recipe 14.11 Dealing with Database Errors Recipe 14.12 Repeating Queries Efficiently Recipe 14.13 Building Queries Programmatically Recipe 14.14 Finding the Number of Rows Returned by a Query Recipe 14.15 Using Transactions Recipe 14.16 Viewing Data One Page at a Time Recipe 14.17 Querying a CSV File with SQL Recipe 14.18 Using SQL Without a Database Server Recipe 14.19 Program: gghGrep Netscape Global History Chapter 15. Interactivity Introduction Recipe 15.1 Parsing Program Arguments Recipe 15.2 Testing Whether a Program Is Running Interactively Recipe 15.3 Clearing the Screen Recipe 15.4 Determining Terminal or Window Size Recipe 15.5 Changing Text Color Recipe 15.6 Reading Single Characters from the Keyboard Recipe 15.7 Ringing the Terminal Bell Recipe 15.8 Using POSIX termios Recipe 15.9 Checking for Waiting Input Recipe 15.10 Reading Passwords Recipe 15.11 Editing Input Recipe 15.12 Managing the Screen Recipe 15.13 Controlling Another Program with Expect Recipe 15.14 Creating Menus with Tk Recipe 15.15 Creating Dialog Boxes with Tk Recipe 15.16 Responding to Tk Resize Events Recipe 15.17 Removing the DOS Shell Window with Windows Perl/Tk Recipe 15.18 Graphing Data Recipe 15.19 Thumbnailing Images Recipe 15.20 Adding Text to an Image Recipe 15.21 Program: Small termcap Program Recipe 15.22 Program: tkshufflepod Recipe 15.23 Program: graphbox Chapter 16. Process Management and Communication Introduction Recipe 16.1 Gathering Output from a Program Recipe 16.2 Running Another Program Recipe 16.3 Replacing the Current Program with a Different One Recipe 16.4 Reading or Writing to Another Program Recipe 16.5 Filtering Your Own Output Recipe 16.6 Preprocessing Input Recipe 16.7 Reading STDERR from a Program Recipe 16.8 Controlling Input and Output of Another Program Recipe 16.9 Controlling the Input, Output, and Error of Another Program Recipe 16.10 Communicating Between Related Processes Recipe 16.11 Making a Process Look Like a File with Named Pipes Recipe 16.12 Sharing Variables in Different Processes Recipe 16.13 Listing Available Signals Recipe 16.14 Sending a Signal Recipe 16.15 Installing a Signal Handler Recipe 16.16 Temporarily Overriding a Signal Handler Recipe 16.17 Writing a Signal Handler Recipe 16.18 Catching Ctrl-C Recipe 16.19 Avoiding Zombie Processes Recipe 16.20 Blocking Signals Recipe 16.21 Timing Out an Operation Recipe 16.22 Turning Signals into Fatal Errors Recipe 16.23 Program: sigrand Chapter 17. Sockets Introduction Recipe 17.1 Writing a TCP Client Recipe 17.2 Writing a TCP Server Recipe 17.3 Communicating over TCP Recipe 17.4 Setting Up a UDP Client Recipe 17.5 Setting Up a UDP Server Recipe 17.6 Using Unix Domain Sockets Recipe 17.7 Identifying the Other End of a Socket Recipe 17.8 Finding Your Own Name and Address Recipe 17.9 Closing a Socket After Forking Recipe 17.10 Writing Bidirectional Clients Recipe 17.11 Forking Servers Recipe 17.12 Pre-Forking Servers Recipe 17.13 Non-Forking Servers Recipe 17.14 Multitasking Server with Threads Recipe 17.15 Writing a Multitasking Server with POE Recipe 17.16 Writing a Multihomed Server Recipe 17.17 Making a Daemon Server Recipe 17.18 Restarting a Server on Demand Recipe 17.19 Managing Multiple Streams of Input Recipe 17.20 Program: backsniff Recipe 17.21 Program: fwdport Chapter 18. Internet Services Introduction Recipe 18.1 Simple DNS Lookups Recipe 18.2 Being an FTP Client Recipe 18.3 Sending Mail Recipe 18.4 Reading and Posting Usenet News Messages Recipe 18.5 Reading Mail with POP3 Recipe 18.6 Simulating Telnet from a Program Recipe 18.7 Pinging a Machine Recipe 18.8 Accessing an LDAP Server Recipe 18.9 Sending Attachments in Mail Recipe 18.10 Extracting Attachments from Mail Recipe 18.11 Writing an XML-RPC Server Recipe 18.12 Writing an XML-RPC Client Recipe 18.13 Writing a SOAP Server Recipe 18.14 Writing a SOAP Client Recipe 18.15 Program: rfrm Recipe 18.16 Program: expn and vrfy Chapter 19. CGI Programming Introduction Recipe 19.1 Writing a CGI Script Recipe 19.2 Redirecting Error Messages Recipe 19.3 Fixing a 500 Server Error Recipe 19.4 Writing a Safe CGI Program Recipe 19.5 Executing Commands Without Shell Escapes Recipe 19.6 Formatting Lists and Tables with HTML Shortcuts Recipe 19.7 Redirecting to a Different Location Recipe 19.8 Debugging the Raw HTTP Exchange Recipe 19.9 Managing Cookies Recipe 19.10 Creating Sticky Widgets Recipe 19.11 Writing a Multiscreen CGI Script Recipe 19.12 Saving a Form to a File or Mail Pipe Recipe 19.13 Program: chemiserie Chapter 20. Web Automation Introduction Recipe 20.1 Fetching a URL from a Perl Script Recipe 20.2 Automating Form Submission Recipe 20.3 Extracting URLs Recipe 20.4 Converting ASCII to HTML Recipe 20.5 Converting HTML to ASCII Recipe 20.6 Extracting or Removing HTML Tags Recipe 20.7 Finding Stale Links Recipe 20.8 Finding Fresh Links Recipe 20.9 Using Templates to Generate HTML Recipe 20.10 Mirroring Web Pages Recipe 20.11 Creating a Robot Recipe 20.12 Parsing a Web Server Log File Recipe 20.13 Processing Server Logs Recipe 20.14 Using Cookies Recipe 20.15 Fetching Password-Protected Pages Recipe 20.16 Fetching https:// Web Pages Recipe 20.17 Resuming an HTTP GET Recipe 20.18 Parsing HTML Recipe 20.19 Extracting Table Data Recipe 20.20 Program: htmlsub Recipe 20.21 Program: hrefsub Chapter 21. mod_perl Introduction Recipe 21.1 Authenticating Recipe 21.2 Setting Cookies Recipe 21.3 Accessing Cookie Values Recipe 21.4 Redirecting the Browser Recipe 21.5 Interrogating Headers Recipe 21.6 Accessing Form Parameters Recipe 21.7 Receiving Uploaded Files Recipe 21.8 Speeding Up Database Access Recipe 21.9 Customizing Apache's Logging Recipe 21.10 Transparently Storing Information in URLs Recipe 21.11 Communicating Between mod_perl and PHP Recipe 21.12 Migrating from CGI to mod_perl Recipe 21.13 Sharing Information Between Handlers Recipe 21.14 Reloading Changed Modules Recipe 21.15 Benchmarking a mod_perl Application Recipe 21.16 Templating with HTML::Mason Recipe 21.17 Templating with Template Toolkit Chapter 22. XML Introduction Recipe 22.1 Parsing XML into Data Structures Recipe 22.2 Parsing XML into a DOM Tree Recipe 22.3 Parsing XML into SAX Events Recipe 22.4 Making Simple Changes to Elements or Text Recipe 22.5 Validating XML Recipe 22.6 Finding Elements and Text Within an XML Document Recipe 22.7 Processing XML Stylesheet Transformations Recipe 22.8 Processing Files Larger Than Available Memory Recipe 22.9 Reading and Writing RSS Files Recipe 22.10 Writing XML