book

Windows PowerShell™ 2 For Dummies®

Name: Windows PowerShell™ 2 For Dummies®
Author: Steve Seguis
ISBN: 9780470371985

by Steve Seguis

August 2009

Intermediate to advanced

408 pages

8h 59m

English

For Dummies

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Copyright
About the Author
Author's Acknowledgments
Publisher's Acknowledgments
Introduction
About This BookConventions Used in This BookWhat You're Not to ReadFoolish AssumptionsHow This Book Is OrganizedPart I: Getting a Bird's-Eye View of PowerShell 2Part II: PowerShell's Basic Structure and SyntaxPart III: Complex Data Description and SharingPart IV: Controlling Where and How You Operate PowerShellPart V: Real-World Windows Administration Using PowerShellPart VI: Configuring and Reporting Via PowerShellPart VII: The Part of TensIcons Used in This BookWhat's on the Web SiteWhere to Go from Here
I. Getting a Bird's-Eye View of PowerShell 2
1. The Windows PowerShell Rap Sheet
1.1. Addressing the Need for a Powerful, Windows-Focused Scripting Language1.1.1. Watching Monad morph into PowerShell1.1.2. A little bit on Windows PowerShell 1.01.2. Windows PowerShell 2, the Next Evolution1.3. Installing Windows PowerShell 21.4. Firing up the Windows PowerShell Command Shell1.5. Going GUI: The Windows PowerShell Integrated Shell Environment (ISE)
2. Customizing and Shortcutting the Environment
2.1. Personalizing the Look and Feel of the Command Shell2.1.1. Adding color to your world2.1.2. Getting size-specific with your windows2.1.3. A window by any other name. . .2.2. Changing Your PowerShell Profile2.3. Making the Windows PowerShell ISE Work for You2.3.1. Customizing the ISE2.3.2. Adding your own functions to the ISE menu2.4. Creating Aliases2.5. Deleting Aliases2.6. Accessing the Alias Drive2.7. Creating Persistent Aliases2.8. Getting to Know Tab Expansion
3. A Pinch of Shell, a Pound of Power
3.1. Getting a Taste of Windows PowerShell3.2. Creating Your First Script3.3. Breaking Down Your First Script3.4. Sneaking a Peek at Complex Scripts3.5. Examining the Nuts and Bolts of the Complist Script
II. PowerShell's Basic Structure and Syntax

4. Shelling Out Commands and Scripts
4.1. Cmdlets: The Little Commands That Could!4.1.1. Putting Cmdlets under a microscope4.1.2. Checking out existing Cmdlets4.1.3. Making Cmdlets understand you4.2. One Shell to Rule Them All4.2.1. Windows Shell scripts4.2.2. Windows Scripting Host
5. When Dollars Turn into Variables
5.1. Discovering Variables: They Vary Very Much5.2. Getting to Know Data Types5.2.1. Dealing with data types5.2.2. Explicitly defining the data type5.2.3. Casting values5.3. Constant and Read-Only Variables5.4. Understanding Automatic Variables5.5. Working with Objects through Variables
6. A Bit of Logic to Save the Day
6.1. A Logic Primer6.2. Branching Using If/Else6.3. Using the Switch Statement6.4. Doing It Over and Over and Over Again with Loops6.4.1. Looping with For6.4.2. Using Foreach to loop through collections6.4.3. Looping for a While6.4.4. Running a loop at least once with Do While6.4.5. Taking a look at Do Until6.4.6. Avoiding loop pitfalls
7. Working on a Pipeline
7.1. Using Pipelines to Streamline Your Commands7.2. Stringing Commands Together7.3. Getting the Right Output
III. Complex Data Description and Sharing
8. Working with Windows Management Instrumentation
8.1. Getting Familiar with Windows Management Instrumentation8.1.1. Examining the WMI architecture8.1.2. Poking around in WMI namespaces8.1.3. Securing WMI8.2. Making Windows PowerShell Interact with WMI8.3. Using SQL Syntax in WMI to Get WQL8.4. Harnessing the Power of WMI8.4.1. Querying service status8.4.2. Looking for event log entries8.5. Changing WMI Authentication Levels8.6. Pretending to Be Someone Else Using Impersonation8.7. Using the New WMI Cmdlets8.7.1. Making things happen with Invoke-WMIMethod8.7.2. Deleting objects using Remove-WmiObject8.7.3. Setting WMI properties using Set-WmiInstance
9. Bringing Strings into the Limelight
9.1. Taking Your First Look at Strings9.1.1. Differentiating between empty and null strings9.1.2. Creating literal strings9.1.3. Simplifying using Here-Strings9.2. Performing String Surgery9.2.1. Combining strings9.2.2. Combining strings with nonstrings9.2.3. Splitting strings9.2.4. Snipping off a piece of a string9.2.5. Performing string substitutions9.3. Working with String Positions9.4. Changing the Case of Strings9.5. Using Regular Expressions9.5.1. Creating the simplest RegEx using literal characters9.5.2. Performing more dynamic searches using character sets9.5.3. Using modifiers to define optional or repeating sequences9.5.4. Using anchors to maintain position9.5.5. Coming up with alternatives9.5.6. Making use of RegEx in Windows PowerShell
10. I'll Take Numbers for $100, Please
10.1. Putting Numeric Data Types under a Microscope10.1.1. Having a look at integral data types10.1.2. Getting precise using nonintegral data types10.2. Doing Some Calculations10.2.1. Adding things up10.2.2. Reducing values with subtraction10.2.3. Expanding through multiplication10.2.4. Reducing through division10.3. Rounding Off Values10.4. Creating Random Numbers10.5. Converting Numbers10.6. Watching Out for Overflow
11. Grouping Data Using Arrays and Hash Tables
11.1. Taking an In-Depth Look at Arrays11.2. Creating and Using Arrays11.2.1. Accessing array elements11.2.2. Looping through arrays11.3. Growing Arrays Dynamically11.4. Creating Multidimensional Arrays11.5. Finding Other Uses for Arrays11.6. Working with Hash Tables: The Array's Useful Cousin11.6.1. Creating and using hash tables11.6.2. Modifying hash tables11.6.3. Looping through hash tables
12. Readin' and Writin' Files
12.1. Having Some Fun with the File System12.1.1. Moving around the file system12.1.2. Managing directories12.1.2.1. Creating directories12.1.2.2. Deleting directories12.1.2.3. Copying directories12.1.2.4. Moving directories12.1.2.5. Renaming directories12.1.3. Manipulating files in the file system12.2. Reading Text Files12.3. Writing Files12.4. Working with XML12.4.1. Reading and writing XML files12.4.2. Saving objects in XML files12.5. Working with HTML
13. Going On a Date with PowerShell
13.1. Going On Your First Date13.1.1. Getting the date and time in a specific format13.1.2. Creating your own dates13.2. Using Date Math (It's Not Just for Nerds)13.2.1. Calculating time differences13.2.2. Looking into the future13.2.3. Checking whether it's daylight saving time13.3. Dealing with Time Zones13.3.1. Standardizing with Coordinated Universal Time13.3.2. Using the TimeZone class
IV. Controlling Where and How You Operate PowerShell
14. Using Functions to Divide and Conquer
14.1. Reusing Code Using Functions14.1.1. Creating your first function14.1.2. Defining parameters14.1.2.1. Defining more than one parameter14.1.2.2. Working with default parameters14.1.3. Returning values14.2. Using Scope14.2.1. Understanding scope rules14.2.2. Watching out for name overlap14.2.3. Defining functions in Global scope14.3. Creating Your Own Cmdlets — Advanced Functions!14.3.1. Understanding the structure of Advanced Functions14.3.2. Defining attributes14.3.3. Defining parameters14.3.4. Using methods14.3.5. Running Advanced Functions14.3.6. Finding uses for Advanced Functions
15. PowerShell Ninjas: Running Jobs Remotely or in the Background
15.1. Using Background Jobs15.1.1. Enabling WinRM15.1.2. Starting a new job15.1.3. Getting results15.1.4. Waiting for a job15.1.5. Terminating a job15.1.6. Bringing a job to a grinding halt15.2. Running Commands Remotely15.2.1. Using Windows PowerShell everywhere15.2.2. Getting what you need for remote commands15.2.3. Speaking PowerShell with a different computer15.2.4. Invoking commands remotely15.2.5. Creating a persistent connection15.2.6. Running remote background jobs15.2.7. Understanding policies, profiles, and precedence
16. Making Your Script Speak Different Languages
16.1. Seeing the Importance of Internationalizing Scripts16.2. Giving Your Scripts Different Tongues16.2.1. Using new internationalization features16.2.2. Understanding cultures16.2.3. Putting it all together16.3. Sharing Scripts with Others
17. Smashing Those Bugs
17.1. Finding Out Where the Bugs Come From17.1.1. Guarding against unexpected input17.1.2. Watching out for incorrect logic17.1.3. Expecting the unexpected: System errors17.2. Understanding the Debugging Process17.3. Working On Your Defense17.4. Working with Debugging Tools17.4.1. Working with breakpoints17.4.2. Setting fancier breakpoints17.4.3. Issuing debugger commands17.4.4. Listing all breakpoints17.4.5. Disabling and enabling breakpoints17.4.6. Removing breakpoints
V. Real-World Windows Administration Using PowerShell
18. Mission Control: All Systems Go
18.1. Monitoring Drive Space18.2. Converting to Windows Management Infrastructure from System.IO.DriveInfo18.3. Managing Windows Services18.3.1. Controlling services18.3.2. Configuring services18.4. Checking Your Event Logs18.5. Querying EventLogs Using WMI
19. Taming the Windows Registry
19.1. Following the Registry Tree19.2. Connecting to the Windows Registry19.2.1. Navigating the registry by using the PowerShell drives19.2.2. Using Microsoft.Win32.RegistryKey to access the registry19.3. Reading Keys and Values19.4. Writing Keys and Values19.4.1. Writing keys and values using the PSDrive19.4.2. Writing registry values using Microsoft.Win32.RegistryKey19.5. Renaming and Deleting Registry Keys and Values19.5.1. Renaming and deleting registry keys and Values using PSDrive19.5.2. Using Microsoft.Win32.RegistryKey to delete registry keys and values
20. Reaching Out to Active Directory
20.1. A Really Brief Active Directory Primer20.2. Connecting to Active Directory20.3. Querying for Objects and Attributes20.3.1. Creating your LDAP filter20.3.1.1. Defining a simple filter20.3.1.2. Using wildcards20.3.1.3. Negating the filter20.3.1.4. Combining filter terms20.3.1.5. Looking up userAccountControl properties20.3.2. Dynamically obtaining a user's distinguishedName20.4. Modifying Object Attributes20.5. Updating Group Membership20.6. Getting to the Raw ADSI Object Using psbase
21. PowerShell Lockdown
21.1. PowerShell Security Features21.1.1. Getting rid of the current directory loophole21.1.2. Stopping the double-click blues21.1.3. Protecting through ExecutionPolicy21.2. Generating a Code-Signing Certificate21.2.1. Creating a self-signed certificate21.2.2. Requesting a certificate from your Enterprise CA21.3. Browsing the Certificate Store21.4. Signing Your Scripts21.5. Managing the Windows Firewall21.5.1. Defining globally open ports21.5.2. Listing firewall services21.5.3. Allowing applications to get through
22. Converting Your Old Scripts: Out with the Old, In with the New
22.1. Converting a Windows Shell Script to Windows PowerShell22.1.1. Echoing to the screen22.1.2. Using conditional statements22.1.3. Migrating that FOR command22.1.3.1. Performing some action for each line in a text file22.1.3.2. Using a FOR loop to split text22.2. Converting a Windows Scripting Host Script to Windows PowerShell22.2.1. Comparing the basics22.2.2. Working with COM objects22.2.3. Understanding the difference between CreateObject and GetObject22.2.4. Handling I/O22.2.5. Working with ActiveX Data Objects (ADO)22.2.6. Leveraging ADO.NET to your advantage
VI. Configuring and Reporting Via PowerShell
23. Controlling Your Network Configuration
23.1. Managing Your Network Settings23.1.1. Familiarizing yourself with Win32_NetworkAdapterConfiguration23.1.2. Retrieving your TCP/IP settings23.1.3. Manipulating your TCP/IP settings23.1.3.1. Troubleshooting connectivity23.1.3.2. Changing TCP/IP settings23.2. Managing Your Windows Firewall23.2.1. Getting to know the Windows Firewall COMmander23.2.2. Enabling and disabling the Windows Firewall23.2.3. Making yourself visible23.2.4. Getting a list of all authorized applications23.2.5. Getting a list of all globally open ports23.2.6. Using the big reset button
24. Managing Your Hardware
24.1. Polling Your Hardware24.1.1. Finding out what hardware you have24.1.1.1. Creating a hardware inventory script24.1.1.2. Detecting whether the computer is a laptop24.1.1.3. Finding any connected USB disk drives and memory sticks24.1.2. Checking hardware state24.2. Controlling Your Printers24.2.1. Connecting to a shared network printer24.2.2. Disconnecting a shared network printer24.2.3. Setting the default printer24.2.4. Checking up on printer state24.2.5. Keeping an eye on the printer queue
25. Making Reporting Easy
25.1. Using Built-In Reporting Cmdlets25.2. Generating Reports25.2.1. Customizing tabular output with Format-Table25.2.2. Setting column width in Format-Table25.2.3. Using an interactive data table25.2.4. Preparing data for other reporting tools25.2.5. Making your data table ready25.3. Making Reports Pretty25.4. Formatting Using Cascading Style Sheets25.5. Using Third-Party Reporting Tools
VII. The Part of Tens
26. The Ten Most Important Cmdlets
26.1. Getting Help with Get-Help26.2. Getting to Know Your Objects with Get-Member26.3. Navigating with Set-Location26.4. Reading Text Files with Get-Content26.5. Writing to a File with Out-File26.6. Leveraging WMI with Get-WMIObject26.7. Creating New Objects with New-Object26.8. Getting Picky with Select-Object26.9. Going Through Collections with Foreach-Object26.10. Controlling the Pipeline with Where-Object
27. Ten Common PowerShell Mistakes
27.1. Forgetting to Change the Execution Policy27.2. Using Commas to Separate Parameters When Calling a Function27.3. Defining Functions After You Use Them27.4. Treating Pipeline Data as Strings27.5. Forgetting to Cast Variables as a String27.6. Using Incorrect Comparison Operators27.7. Trying to Do Too Much in One Pipeline27.8. Forgetting About Variable Scope27.9. Not Using the Debugger27.10. Not Using .NET Classes When Available
BC1. Handling Exceptions
BC.1. Handling Errors the Old-Fashioned WayBC.2. Understanding ExceptionsBC.3. Trapping ExceptionsBC.4. Throwing Exceptions

Content preview from Windows PowerShell™ 2 For Dummies®

Chapter 17. Smashing Those Bugs

In This Chapter

Keeping bugs in check
Examining bugs under a microscope
Using the debugger for effective eradication

One of the most frustrating things about writing any kind of code, such as a Windows PowerShell script, is that inevitably you'll run into a bug. A bug occurs when a piece of code does something that it's not supposed to do or acts a way that it wasn't designed to act. I'm not talking about bugs in Windows PowerShell itself, but bugs in Windows PowerShell scripts that you or someone else wrote. The nastiest kind of bug is one that's hard to reproduce. I like to call this type the sneaky bug (though you might refer to it as your in-laws). Whatever it is, when you do find a bug, you need to exterminate it quickly; otherwise, that bug will be staring right into your face someday at the most inopportune moment.

In this chapter, you make use of the new debugging features in Windows PowerShell 2 that'll make it much easier to track down errors in your code so you won't have to keep hitting your head on the wall in frustration the next time your script doesn't work as you expect.

Finding Out Where the Bugs Come From

Software bugs are never intentional. Instead, they usually occur when the script or program enters a state that it wasn't designed for. When you find a bug in a script, you'll usually find that it's caused by one of these situations:

Unexpected input
Incorrect logic
System error

Guarding against unexpected input

Unexpected input occurs when ...

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