As an A+ Certified Professional, you will want to use the full range of

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1 Bonus Chapter 1: Creating Automation Scripts In This Chapter Understanding basic programming techniques Introducing batch file scripting Introducing VBScript Introducing PowerShell As an A+ Certified Professional, you will want to use the full range of tools available to you. This chapter introduces you to the world of scripting, which can be used in conjunction with other content in this book to set up automation tasks to make your job easier. A script can migrate files around your network, back up settings, or create a report related to changed settings. Basic knowledge of scripting is helpful for all A+ certified technicians, who will use scripts as part of their job, as I regularly do; however, CompTIA does not have any exam objectives which map to scripting objectives. Feel free to use this chapter as a primer for your scripting use; but do not focus on it for exam review. The three scripting or automation languages you will see are as follows: Batch files VBScript PowerShell When taking a look at these options, you will see how to use basic program flow and control structures, which include parameters, logic controls, loops, functions, and subroutines. When you see the remaining languages, you will draw on the knowledge introduced in earlier sections of the chapter. Although the language and syntax may change, the concepts remain consistent for any programming language.

2 BC2 Creating Your Files Creating Your Files Regardless of the type of scripting language that you decide to use, you will need to edit text files to create your scripts. The most consistent program to use is Notepad, but other available programs can perform actions such as syntax highlighting, indentation, and line numbering. Starting your file To start, you need a place to put the commands that you want to execute. To do this, open the text editor of your choice, make a new text file, and save it with an appropriate extension (.bat,.ps1, or.vbs). If you re using a Windows-based editor (such as Notepad) and the operating system option of Hide File Extensions for Known File Types is enabled, you must enclose your filename in quotation marks when saving it. If you want file extensions to show, use the following steps: 1. Open My Computer (or Computer for Vista users). 2. Choose Tools Folder Options. 3. Click the View tab. 4. Deselect (to show) the Hide File Extensions for Known File Types check box. 5. Click OK. With your file open in the text editor, you can now type any commands you want, but remember to put only one command per line in your file. For a batch file, you can use this file to create, copy, or delete files, or anything else that you could do from the command prompt. After you create a file, you can execute it directly, if it is a batch file, by typing the path to the file and the filename at the Start Run command or at a command prompt. VBScript files and PowerShell files may take a little more to get going. When working with PowerShell, Microsoft provides a tool that towers over Notepad, but either can be used to create PowerShell scripts. This tool is powershell_ise.exe, or the PowerShell Integrated Scripting Environment, as shown in Figure 1-1. Tabs at the top of the editor allow you to have multiple files open at once, and the multiple panes allow you to edit the script, execute it, and see the output without needing to move between applications. In addition, because the ISE knows PowerShell, it performs syntax coloring, which makes it easier to read and follow your code.

3 Going Back to Basics with Batch Files BC3 Script Pane Output Pane Figure 1-1: The PowerShell Integrated Scripting Environment (power shell_ ise.exe). Command Pane Going Back to Basics with Batch Files I strongly recommend doing testing with the batch file on a test computer. I have seen people create batch files with improperly formatted rmdir commands, which then deleted many more files and directories than expected. If you use commands that format partitions, remove files, or delete disk partitions, note that poorly structured commands might result in you being required to reinstall the operating system on your computer. The commands suggested in this section are not dangerous. Getting your directions Many people want to be able save the output of their commands or, more rarely, answer questions or provide input for a command. There are a few ways to do this, and Table 1-1 summarizes the differences among the options. All these options require that your program is generating

4 BC4 Going Back to Basics with Batch Files output going to stdout (standard output) or accepting input from stdin (standard input). stdout and stdin are interfaces or objects that C programmers use almost exclusively when requiring data input and output for command line programs. As a programmer, I can write an application that sends its output to an interface called stdout, and then I let the operating system deal with where that actually is: It might be a teletype terminal, printer, monitor, or text file. For all versions of Windows, data sent to stdout will be displayed in a command prompt window. Table 1-1 Symbol Function Redirection Symbols < Sends the contents of a file listed on the right into the command on the left. This is useful when you want to provide an answer to a question that a command will prompt for (for example, when the format command prompts for confirmation). By creating a one-character text file with just Y and a return or enter, you can pass a yes into the format command. > By specifying a command on the left and a text file or nul on the right, you can prevent output of a command from going to the screen. Instead, output is passed to the file listed on the right side. If the file exists, it will be overwritten. This is extremely useful if you want to log the results of certain statements. >> Similar to the > symbol except that the output is appended to the destination file if it already exists. If the file does not exist, it will be created. The pipe pipes, or directs, the output of the file that is listed on the right side into (as input) the command listed on the left. This may allow you to bypass the creation of a text file. Working with parameters or starting arguments You can get a lot more mileage from your batch files if you pass and use arguments with them. An argument is a piece of data passed to the batch file or command when typing the command, such as copy C:\this.txt C:\that.txt which has two arguments: C:\this.txt and C:\that.txt. You can use ten arguments with a batch file. This really drops off to nine because the

5 Going Back to Basics with Batch Files BC5 first argument is %0, and that represents the name of the running batch file. %1 through %9 can be used as arguments for your batch file. If you have a batch file that copies files from one directory to another, you can make your batch file more reusable by working with arguments. Here is an example of this concept: Old batch file StaticCopy.bat: xcopy c:\dos\*.* c:\dosback This file could be made more generic with these modifications: New batch file DynamicCopy.bat: xcopy %1 %2 This new batch file would be run by using dynamiccopy c:\dos\*.* c:\dosback It s true that you are typing more to achieve the same result. But you have to consider that this line could be in a much larger batch file, which could use the two parameters (%1 and %2) in many different ways. This could actually save you a lot of typing when creating and editing your batch file because the parameters can be used rather than hard coding the paths or parameters. This system works fine until you find yourself in a position in which you need more than nine parameters passed to your batch file. However, if you plan the order in which you use your parameters, you can actually support many more than nine. This is done with the shift command. Each time you use shift in your batch file, all parameters that are passed to your batch file are shifted over one position. For example, %2 becomes %1, %3 becomes %2, and so on. Making batch files make decisions So far, you have seen some ways to make your batch file more generic. Now, I ll show you how to make it think for itself or at least think for you. There are two ways to get your batch file to make some decisions although after you read this section, you might argue that there is only one way, seeing as how both ways make use of batch file labels. First, the if and :label statements introduce simple program flow logic. For example, if you know that you need two parameters passed to your batch file for it to work properly, you can use something like Listing 1-1 in your batch file:

6 BC6 Going Back to Basics with Batch Files Listing 1-1 Passing Two Parameters to a Batch File if not!%2==! goto correct :Instructions echo. echo Please provided two parameters. The first is the echo source directory, and the second is the destination. echo. goto end :correct xcopy %1 %2 goto end :end When working with the if statement, you evaluate whether two options are the same or whether a condition is true. In this case, you are testing for two items being equal. To do this, you need two items because you cannot test equality with only one item. In this example, you want to see whether the second parameter is blank, so you use %2, which represents the second parameter. However, you cannot use if not %2== because that would evaluate %2 to nothing, and you need something on the other side of the equation. This gets worse if the second parameter was not passed to the batch file because %2 will not exist, and you are then asking whether nothing equates to nothing. The if statement cannot handle evaluating nothing in an equation. To make sure there is something to evaluate on both sides of the equation and not change the results you need to add a character to both sides of the equation. In this example, I chose to use the exclamation mark. You should also take note of the use of the word not to reverse the results of the test. Some other items that the if statement can test for includes OS environment variables and whether files and directories exist. To test an environment variable for a specific value, you use a command like this one that checks the name of the computer that is running the batch file: if!%computername%==edspc goto instructions To test whether a file exits, you use something like if exist c:\autoexec.bat goto Instructions If you want to know whether a directory exists, you can test for nul, which only exists for your test if a directory is there: if exist c:\windows\nul goto Instructions

7 Going Back to Basics with Batch Files BC7 The full example also shows you how to work with labels and the goto statement. The goto statement uses only the first eight characters of the label, so try to keep label names unique. The goto statement requires a destination in the batch file to be sent to, and that is where the labels come in. Although end is a label that is meaningful to you, it is just another label to the batch file. If you use a goto in your batch, you must have a matching label, or you will get errors, and your batch file will not work. The last method of controlling the flow of your batch file is using the choice or set statement. The choice statement allows you to pause your MS-DOS or Windows batch file to wait for input. Input to the choice statement is a single character. Listing 1-2 shows an example of how to use the choice statement: Listing 1-2 Using a choice off choice /c:ynm You choose if errorlevel == 3 goto m if errorlevel == 2 goto n if errorlevel == 1 goto y goto end :y echo You chose Yes. goto end :n echo You chose No. goto end :m echo You chose Maybe. goto end :end The choice statement uses the list of parameters after the /c: to listen to input. One of those choices must be provided. The choice statement will actually ignore any other input and wait for one of those choices. Also, take note of how to handle the input afterward. Each choice is assigned a number, based on its order: Y = 1, N = 2, and M = 3. The if statement should actually be read as, If the error level is greater than or equal to x, go to label.

8 BC8 Going Back to Basics with Batch Files Because of how the computer handles if statements, always test the errorlevel from the highest to the lowest. If you test the values in the wrong order and start your evaluation with if errorlevel = 1 goto y, everything will satisfy this test because all possible values are greater than or equal to 1. If you are using Windows XP, you can do the same type of thing in your batch file by using the set command, but I find set to be an inferior tool for this type of test. I suggest getting choice.exe from a Windows Vista computer. Starting with Windows Server 2003, Microsoft has included choice.exe, and it supports slightly different options than the MS-DOS version. This version of choice.exe is also compatible with Windows XP. Listing 1-3 holds a copy of the same batch file using the Windows Server 2003 choice command. Notice the /M and the quotes around the message text: Listing 1-3 Batch File using Windows Server 2003 choice off choice /c:ynm /M You choose if errorlevel == 3 goto m if errorlevel == 2 goto n if errorlevel == 1 goto y goto end :y echo You chose Yes. goto end :n echo You chose No. goto end :m echo You chose Maybe. goto end :end The if, choice, and set statements add many options to the design of your batch files; they can help you make batch files that are flexible and comprehensive. Looping I hate having to repeat myself, and if you feel the same way, loops are for you. Loops can be used inside or outside batch files with only a small

9 Going Back to Basics with Batch Files BC9 modification. The loop is a for loop and requires a list of values that are assigned to a variable and a statement that uses that variable. The variable is assigned with a preceding % character outside a batch file, and two % characters when used within a batch file. Here is an example of a loop at the command prompt: echo off for %x in (hello world) do echo %x The output of the previous loop would be hello world If done in a batch file, the loop would look like this: echo off for %%x in (hello world) do echo %%x Loops may cut down your work when you have several repetitive lines in your batch file. Locating a command When you type a command at a command prompt, in a batch file, or at the Run command, your computer follows a set of steps to locate the command: 1. The computer checks the current directory for the command. 2. If the command is not found in the current directory, the computer checks all directories listed in the Path environment variable. If the command is not located possibly because you misspelled it you see the following message: Bad command or file name If you see this message, check the spelling of the command and try again. The path variable can be set in the autoexec.bat file for all Microsoft OSes. It is the only environment variable that can be set without using the set command. To set the path variable, you can use either set path = c:\windows;c:\windows\system or path = c:\windows;c:\windows\system

10 BC10 Going Back to Basics with Batch Files The only advantage to the latter is that it uses four fewer keystrokes. If both c:\windows and c:\windows\system are in the path, they will be checked when a command that is typed is not in the current directory. Windows computers provide an additional location for setting the path environment variable. To change the path on a Windows XP computer, open the system Control Panel, click the Advanced tab (or the Advanced system settings for Windows Vista and Windows 7 users), and click the Environment Variables button. You can use the Environment Variables dialog box to modify the path for the computer. Putting it together Listing 1-4 is a short batch file that has been documented with rem (remark) statements throughout the file. It shows a completed file that uses many of the techniques discussed in this section. This batch file was designed to gather the TCP/IP configuration from a computer and place it in a text file on the C: drive; but it could place the information on a drive on a server so that it could be collected by an administrator. The text file that the batch file creates is named for the computer information from which the information was gathered. This data is collected only once. The networking troubleshooting commands used in this file can be found in Book VIII, Chapter 3. Listing 1-4 Batch file documented with rem Statements rem Check for existing file, and if it exists, exit the batch file, rem and make the directory if it does not exist. if not exist C:\IPSettings\nul mkdir C:\IPSettings if exist C:\IPSettings\%computername%.txt goto end rem Check to see if the computer is running Windows 9x rem or Windows NT style OS. if not!%os%==!windows_nt goto Win9x :WinNT rem Create a new file containing the output of ipconfig.exe rem which is the current TCP/IP Configuration. ipconfig /all > C:\IPSettings\%computername%.txt rem Add to this file the current routing table using netstat.exe netstat.exe R >> C:\IPSettings\%computername%.txt rem Skip the Windows 9x section and goto the end of the file. goto end :Win9x rem Use Windows 9x compatible versions of the Windows NT commands rem networking commands. winipcfg /all /batch C:\IPSettings\%computername%.txt netstat.exe R >> C:\IPSettings\%computername%.txt :end If this file is saved to C:\Windows\GetIPSettings.bat, it can be executed by specifying the name of the file GetIPSettings in a command window or by typing it after choosing Start Run. By specifying the name, the entire path on your computer will be searched for the file with.com,.exe,.cmd, or.bat as the file extension.

11 Working with VBS BC11 Working with VBS Without going to third-party solutions, Windows was limited to batch files for automation prior to the release of Visual Basic Scripting (VBScript) around 1996, shortly after which it was included automatically with the Windows OS. As the name suggests, it is based loosely on Visual Basic. While not as powerful or fast as a Visual Basic application, VBScript offers the following benefits: It is easy to write programs in, it does not require a compiler to operate, and it does not require a custom application to be installed to be able to write a program (you only need notepad.exe). The main competition to VBScript when it was released was from JavaScript, which offered many of the same benefits as VBScript, but JavaScript required the installation of Java support on your computer. Calling a script While I said you do not need to compile your scripts in VBScript, you do need to use a command interpreter to execute them. Microsoft provides two interpreters with the Windows OS: wscript.exe: This is a Windows-based interpreter. When you double-click your script to execute it, it will run using Windows Script. Some commands in your script will behave differently if you are using wscript over cscript. cscript.exe: This is a command-line interpreter and is run from a command window (cmd.exe). The default output location for cscript. exe is called stdout, and it is the command window. This allows you to use commands like wscript.echo to send data to the command window when your script is running. If you want to change the default script interpreter for Windows, type cscript //H:CScript in a command window, while typing cscript //H:WScript will put you back the OS default. To execute, run, or call the script, you can double-click in Windows Explorer to launch it with the default interpreter, or you can type in the name of the interpreter followed by the path to and name of the script in the Run command or in a command window, like cscript C:\MyScripts\Test-script.vbs. If you use this command in the Run command, the script will run in a command window, and the window will close when the script completes. So if you want to see the output, run the script from an open command window. Script structure Most programming languages follow a common structure that breaks down into four basic sections. These are Declarations, Main, Functions, and

12 BC12 Working with VBS Subroutines. Within each of these sections are the lines of programming that will make your script or program function. Declarations Most programs will have a number of variables or constants with which they will work. The Declarations section is where you will put these items. Think of it like algebra: Let X = 5 and Solve for Y. In most languages, variables and constants may contain numbers, strings (text), or Boolean values. While some programming languages require that you state the type of value you are going to place in a variable, VBScript declares all variables automatically as variant. This means that they could hold a variety of types of values. Here are a few variables that are defined in a script; three variables are set, two are used for strings (which are enclosed in quotes), and one is for an integer. After defining the variables, strfilepath and iprintercount have values set: Dim strfilepath, strdatarow Dim idoprtrsize strfilepath = N:\temp\ iprintercount = 0 Constants differ from variables in that they cannot change, like Pi or the speed of light. In programming, when you declare a constant for use, you will define the value to use at the same time. Here is a series of constants that will be used when working with files in VBScript: Const OPEN_FILE_FOR_READING = 1 Const OPEN_FILE_FOR_APPENDING = 8 Const OPEN_FILE_FOR_WRITING = 2 Const CREATE_FILE_IF_NEEDED = 1 Const OVER_WRITE_FILE = 1 The other item that gets declared in this section are objects. Objects are a little different than variables in that they contain properties (which hold values) and methods (actions that they can perform). Two of the common objects you will use in your scripts are Scripting.FileSystemObject and WScript.Shell. The File System object is used to manipulate files on your hard drive. You would use this to copy or move files, as well as to open, write to, and close text or binary files. The Shell object allows you to access system environment variables and to run commands (other programs). Here you define a variable and associate an object with it through the set command. Later you will create a file object and save data to the file. Dim ofilesystem Set ofilesystem = CreateObject( Scripting.fileSystemObject )

13 Working with VBS BC13 VBScript will actually allow you to use variables without first declaring them, which can cause problems if you are fat-fingered. The following script is an example of this problem: Dim strmyname, strnameplus strnyname = Ed Tetz strnameplus = strmyname & is awesome. Now, if you go to use the variable strnameplus, you will expect it to contain Ed Tetz is awesome. when it actually contains is awesome. This script will not generate an error letting you know that a problem exists, but it will not function the way you expect. The solution is option explicit, which forces you to declare all variables that you will be using. If you attempt to run a previous script with option explicit, when you attempt to run the script, you will see an error, telling you that an undeclared variable existed. Main procedure The main part of the program or script is all the Main procedure. When the script executes, this is where the main flow of logic comes from. In VBScript, the main function starts automatically after the variables are declared and continues until a WScript.Quit(0) is encountered. In some languages, the Main procedure is identified by name. Good programming practice typically means that the Main procedure will be short and identifies the main flow of the program. Most of the work done by the script will be in the form of subprocedures and functions. Subprocedures or subroutines A subprocedure or subroutine is a section of a program that performs a set of commands and returns to the subprocedure or function that called it. It is like giving a task to someone to complete, and when the task is done, the person comes back to you to tell you it is done. You can define locally used variables at the start of the subprocedure in the same way that you declared variables for use at the start of the Main procedure. You can pass parameters to a subprocedure, or the subprocedure could have no parameters. When passing parameters, you can use values or variables when calling subprocedures. Listing 1-5 shows what a simple subprocedure would look like; this sample includes a section of the Main procedure and makes use of the message box function to display results.

14 BC14 Working with VBS Listing 1-5 A Simple Subprocedure Dim inumone, inumtwo inumone = 5 inumtwo= 6 AddNumbers inumone, inumtwo WScript.Quit(0) Sub AddNumbers (ifirstnum, isecondnum) Dim itotal itotal = ifirstnum + isecondnum MsgBox itotal End Sub Here are a few things to make note of in this example: Local variables: ifirstnum, isecondnum, and itotal are local variables that only exist inside of the AddNumbers subprocedure. Passing variables: inumone and inumtwo are values that are passed to variables ifirstnum and isecondnum in the AddNumbers subprocedure. Passing values: Rather than passing values stored in variables, you can also call the AddNumbers subprocedure with values, like AddNumbers 3, 6. Ending the subprocedure: Procedures and many other structures have both a starting and an end; in many cases, the end uses the control word end. Functions A function is similar to a subprocedure with one major difference: A function returns a value to the calling procedure. Any type of calculation can be performed within the function, and those results can be passed back. So take a look at the last script being changed to a function in Listing 1-6. Notice that the message box is now in the Main procedure, using the value returned from the function. Listing 1-6 A Simple Function Dim inumone, inumtwo, itotal inumone = 5 inumtwo= 6 itotal = AddNumbers(iNumOne, inumtwo) MsgBox itotal WScript.Quit(0) Function AddNumbers (ifirstnum, isecondnum) AddNumbers = ifirstnum + isecondnum End Function

15 Working with VBS BC15 Here are a few things to make note of in this example: Brackets: Brackets surround the parameters in a function. This defines for VBScript that you are using a function and that a value will be returned. Function variable: The function name is treated like a variable within the function, and this is used to set the value that will be returned by the function. Because Listing 1-6 had you set itotal and use that in a message, you can optimize your code a bit by eliminating that itotal, which you see in Listing 1-7. Listing 1-7 Streamlined Function Dim inumone, inumtwo inumone = 5 inumtwo= 6 MsgBox AddNumbers(iNumOne, inumtwo) WScript.Quit(0) Function AddNumbers (ifirstnum, isecondnum) AddNumbers = ifirstnum + isecondnum End Function Decisions and Boolean logic When you have a program that is going to perform a task for you, you will probably have the program perform some type of decision making along the way. To perform these decisions, you will use Boolean logic to make these decisions. Two main decision structures that are used are If and Case. The If statement opens with an If and a condition (which is evaluated to see whether it is true) and closes with an End If. Two other optional elements are in the statement: ElseIf and Else. Else is the action to take if the If condition is not met, whereas ElseIf combines an Else with another If statement. If you have used an ElseIf, you are still able to use an Else. Listing 1-8 shows an example of a complete If statement. Listing 1-8 Dim a, b, c a = 5 b = If a > b Then c = a If Statement

16 BC16 Working with VBS ElseIf b > a Then c = b Else c = a + b End If Listing 1-9 shows the Select Case statement, which is similar to If statements in that they make decisions. But they are used to evaluate the contents or results of a single statement rather than different criteria at each ElseIf statement. Listing 1-9 Select Case Statement Dim Name Name = Bobby Select Case Name Case Jane MsgBox Jane is awesome. Case Judy MsgBox Judy is great. Case Bobby MsgBox Bobby is the best. End Select Loops If something is worth doing, it is worth doing again, and again, and again. In most cases, within your program or script, you will want to repeat certain steps several times. Perhaps you want to perform an action on every text file in a folder, or perform a step 100 times, or perform an action until a certain condition is met. If this is the case, you would like to loop. For Next The For Next loop works with a counter to loop between two values, using an increment or step value, with the default value being 1. The loop repeats every command from the For statement to the Next statement. Notice that in Listing 1-10, the value of i is joined (or concatenated) with the string by using the ampersand (&), which is used to join strings or string variables together. Listing 1-10 For Next Loop Dim i For i = 2 to 10 step 2 MsgBox The current value of i is: & i Next

17 Working with VBS BC17 For Each Next The For Each Next loop requires a collection of some sort to function. These collections may be created on the fly by inspecting an object, such as the files in a folder of the FileSystemObject or the properties of a file. The other item that may be used for a collection is an array. To keep things easy, in Listing 1-11 you create an array that will be used for the looping. Listing 1-11 For Each Next Loop Dim Egg, Eggs(2) Eggs(0) = Robin Eggs(1) = Eagle Eggs(2) = Hawk For Each Egg in Eggs Wscript.echo The current egg is: & Egg Next Unlike the For Next loop, which increments a value, this loop will cycle through the collection of objects until the collection is complete. While The While loop continues the loop while the test condition remains to be true. The items in the loop condition need to be modified in the looping process so that there is a chance that the condition will eventually become false. Unlike other statements that have an End, the While loop ends with a While End, or rather Wend. Listing 1-12 provides a sample of this loop. Listing 1-12 While Loop Dim i i = 0 While i < 10 Wscript.Echo The current number is: & i i = i + 1 Wend While the While loop is still used by some people in VBScript, it is on its way out of favor in preference for the Do Loop command, which achieves the same results. Do Loop The Do Loop command supports either While or Until conditions, which may be tested either at the start of the loop or at the end of the loop. The four options for looping that you could use are shown in Listing 1-13.

18 BC18 Working with VBS Listing 1-13 Do Loop Dim i i = 0 Do While i < 10 Wscript.Echo The current number is: & i i = i + 1 Loop i = 0 Do Until i >= 10 Wscript.Echo The current number is: & i i = i + 1 Loop i = 0 Do Wscript.Echo The current number is: & i i = i + 1 Loop While i < 10 i = 0 Do Wscript.Echo The current number is: & i i = i + 1 Loop Until i >= 10 Screen output If you want to view what is going on in your script, you can send output to the screen. You can use two basic commands: One is the message box (MsgBox) command, and the other is the Wscript.echo command. Wscript.echo The echo command simply tells your script to send a copy of the data you provided to the standard output of the script interpreter. For wscript. exe, this would be a message box, while cscript.exe will send the output to the command window. For scripts that generate a lot of output, you will want to run them through cscript.exe to avoid a huge series of message boxes. MsgBox The MsgBox option will work through either cscript.exe or wscript. exe. This command will open a message box on the screen with a provided title, message, and buttons. This command can be called as subprocedure or as function, with the function returning the value of the button that is clicked in the message box. Brackets enclose the parameters of the function, while if it is called without brackets, it will operate as a subprocedure and not return that value. Here is the syntax of the MsgBox command: MsgBox(prompt[,buttons][,title][,helpfile,context])

19 Working with VBS BC19 Note the square brackets, identifying options, where prompt is the only required parameter for the command. If no title is given, the default Windows Script Host is used. For buttons, the default is an OK button, but you can choose to display multiple buttons in your message box; this is only useful if you are using it as a function. You can use either the constant name or the number for the button parameter: 0: vbokonly: OK button only 1: vbokcancel: OK and Cancel buttons 2: vbabortretryignore: Abort, Retry, and Ignore buttons 3: vbyesnocancel: Yes, No, and Cancel buttons 4: vbyesno: Yes and No buttons 5: vbretrycancel: Retry and Cancel buttons 16: vbcritical: Critical Message icon 32: vbquestion: Warning Query icon 48: vbexclamation: Warning Message icon 64: vbinformation: Information Message icon If you want to display a message box with vbokcancel buttons and have the message box show a vbquestion icon, add the two numbers together and use 1+32, vbokcancel+vbquestion, or 33, as the button parameter. Putting in more than the OK button only makes sense if you are going to do something with the information, so you will use the MsgBox as a function and get information back regarding the button pressed. This function will return the following values if the matching button is pressed: 1: vbok: OK was clicked 2: vbcancel: Cancel was clicked 3: vbabort: Abort was clicked 4: vbretry: Retry was clicked 5: vbignore: Ignore was clicked 6: vbyes: Yes was clicked 7: vbno: No was clicked Listing 1-14 has an example of this function in action. Note the use of vbcrlf to break the prompt into two lines and the underscore to break the line into two pieces for readability (the extra spaces on the second line are ignored).

20 BC20 Working with VBS Listing 1-14 Message Boxes Dim Answer Answer = Msgbox( Is blue your favorite color. & vbcrlf & Answer honestly., _ vbyesno +vbquestion, Favorite Color ) if Answer = vbyes then WScript.echo Blue is your favorite color. Else WScript.echo Your favorite color is not blue. End If By implementing message boxes as functions, you can control the flow of operations in your script. Opening and saving files You have already been introduced to the FileSystemObject, at least in principle. Now you will take a look at a couple of things you can do with this object, specifically opening a file to read data and opening a file to write data into a file. In Listing 1-15, you will read the contents of a file, add a line number to the beginning of each line, and write these lines of data back out to another file. Listing 1-15 Reading Files Dim ofso, oreadfile, owritefile, TextLine, i Const ForReading = 1 Const ForWriting = 2 Const ForAppending = 8 i = 1 Set ofso = CreateObject( Scripting.FileSystemObject ) Set oreadfile = ofso.opentextfile( C:\Temp\InputFile.txt, ForReading) Set owritefile = ofso.createtextfile( C:\Temp\OutputFile.txt, True) Do Until oreadfile.atendofstream TextLine = oreadfile.readline owritefile.write i & : & TextLine & vbcrlf i = i + 1 Loop oreadfile.close owritefile.close Working with parameters You can do only so much inside a script without needing to make changes to it. To reduce the number of times that you need to make changes to a script, you can call the script with arguments (also called parameters). Listing 1-16 is an example of working with arguments within a script.

21 Getting More Power with PowerShell BC21 Listing 1-16 Working with Arguments args = WScript.Arguments.Count If args < 1 then WScript.Echo Usage: args.vbs argument [argument] [argument] [argument] WScript.Quit end If WScript.Echo You entered & args & arguments and they are as follows. For i = 0 to args - 1 WScript.Echo Argument number & i & is & WScript.Arguments.Item(i) Next The arguments that the script receives can then be put into variables to be used through the rest of the script. Executing external commands From within your script, you may want to run another command at the OS level. In Listing 1-17, you perform a directory listing in a new window and leave that window open. The directory that is listed is provided by a variable in the script, but it could also be provided as an argument. Listing 1-17 Executing External Commands Dim oshell, directory directory = C:\Temp Set oshell = WScript.CreateObject( WScript.Shell ) oshell.run cmd /K CD & directory & & Dir Set oshell = Nothing The last line of the script is a bit of cleanup, where you destroy the object that was created earlier. Forcing a stop When running your scripts, at times the script will get into a loop or generate a series of message boxes that seem to never end. If you want to stop a running script, open Task Manager and navigate to the Processes tab. Now locate the wscript.exe process, right-click, and choose End Process. This will terminate the script where it is. Getting More Power with PowerShell PowerShell is a new scripting language developed by Microsoft. Microsoft released PowerShell as an update to VBScript and to offer a new command-

22 BC22 Getting More Power with PowerShell line management interface for new OS and server functions. In addition to the language itself, Microsoft also created a series of command applets, or cmdlets, to perform a series of preset functions. PowerShell is an optional feature on current Windows OSes and is available as an optional component on Windows XP via Windows Update. Calling a script If you run powershell.exe by itself, you will enter interactive mode, where you can issue cmdlets or commands, such as get-command, to get a listing of the installed cmdlets. You can also run these commands from the command line using the format of powershell.exe get-command. I introduce you to some Windows OS cmdlets later; these represent much of the power of PowerShell. Different components installed on your computer can install their own PowerShell console and cmdlets; this would include Microsoft Exchange and VMware vsphere. As with VBScript, you can create a text file containing a series of commands, loops, and conditional statements, and then execute this script file from the command line. These script files have an extension of.ps1 and can be called using this command: powershell.exe C:\Temp\MyScript.ps1 Before you are able to run a script, you need to ensure that the Execution Policy allows you to execute scripts. Run the command Get- ExecutionPolicy. If it is set to Restricted, you will need to change it, which you can do with the following command: Set-ExecutionPolicy Unrestricted When you run this command, you will need to confirm the security change. Cmdlets Much of the power of PowerShell lies in the cmdlets. One cmdlet you should know is Get-Help. Cmdlets are named telling you what their actions will do. They start with an action or verb (like Add, Set, or Get) and end with a noun (like Computer, EventLog, or Service). All commands have modifiers or parameters that can be used. When running your commands to retrieve data, you can filter the output by including these parameters. Listing 1-18 shows the output of the Get-Service command, with a restriction showing only some of the services. Notice the * wildcard used in the command.

23 Getting More Power with PowerShell BC23 Listing 1-18 Working with Cmdlets PS C:\temp> Get-Service -Name Remote* Status Name DisplayName Stopped RemoteAccess Routing and Remote Access Stopped RemoteRegistry Remote Registry Output from this command can be passed to another command by way of the pipe symbol ( ). In Listing 1-19, you will pipe to the Format command to format the output. In Powershell, pipe is also called pipeline. Listing 1-19 Working with Pipe PS C:\temp> Get-Service -Name Remote* Format-Wide RemoteAccess RemoteRegistry Script structure Some people will say that PowerShell is sloppy, while others will say it is free-form and efficient. Unlike VBScript, which is very structured in its format, PowerShell offers a lot of flexibility. Declarations Unlike VBScript, in PowerShell you do not declare your variables; you simply start using them. You can, however, start using them right away, but if you want to be more formal, you can use the Set-Variable command. When using variables, you will use the $ operator to identify them: Set-Variable Name strmyname Value Ed Tetz $strtrait = is an author. A number of characters are not allowed in variable # % &,. and spaces. Additionally, certain reserved keywords used in PowerShell are not allowed to be used as variable names: break, continue, do, else, elseif, filter, foreach, function, if, in, return, switch, until, where, and while. Although it is a good idea, it is not required to start a variable name with the type of data that you are storing in the variable. This includes strings (strname), integers (intage or iage), and Boolean (bcorrect) to name a few. Naming your variables this way avoids keyword conflicts and lets you keep track of the data that is found in the variable.

24 BC24 Getting More Power with PowerShell While PowerShell will attempt to decide on the fly what types of variables you are working with, you do have the option of hard-coding the variable types by declaring your variables like this: [str]$strmyname= Ed Tetz Other variable types would be array: Array of values byte: 8-bit character bool: Boolean value char: Unicode 16-bit character decimal: 128-bit decimal value double: 64-bit decimal number hashtable: Hashtable object int: 32-bit signed integer long: 64-bit signed integer single: 32-bit decimal number str: Fixed-length string of Unicode characters xml: XML object Main procedure and functions One big difference between VBScript and PowerShell is how you code the main procedure and functions. Function blocks can be created anywhere in your code, but it is good form to place all your functions at the start of your script. In most cases, you need to define the function before you use the function. If you are in the middle of your script and you need to exit immediately, a command is available to you. In VBScript, you could use WScript.Quit(0), but in PowerShell, you have the break command. The break command has a partner in the continue command. If you want to exit the current function, loop, or main procedure, you can use break. Every structure with separated code, be it a function or a loop, will be enclosed in braces { }. If you place a break within that block, the block will immediately be exited. If the break command is used outside all blocks, the main procedure will be exited. The continue command is a little different from the break command. Like the break command, the continue command could be used in a loop; but rather than exiting the loop entirely, the continue command will skip over all remaining commands in the loop and return to the beginning of the loop for the next iteration.

25 Getting More Power with PowerShell BC25 So a short script would look like the code sample in Listing Listing 1-20 PowerShell Scripts $x = 5 $y = 6 $Ans = $x + $y Write-Host The answer is $Ans If you wanted to use a function, the code sample would look more like Listing Listing 1-21 PowerShell Function Function AddNums ($Num1, $Num2) { $Ans = $Num1 + $Num2 return $Ans } $x = 5 $y = 6 $x = AddNums 5 6 The Answer is $x Decisions and Boolean logic When making decisions in PowerShell, you will need to be familiar with the comparison operators, which you can find in Table 1-2. Table 1-2 Operator -eq -lt -gt -le -ge -ne -ieq -ceq Comparison Operators Description Equal to Less than Greater than Less than or equal to Greater than or equal to Not equal to Text comparison, case insensitive equal to Text comparison, case sensitive equal to

26 BC26 Getting More Power with PowerShell Boolean operators can also be used to modify the returned values and change the result of a Boolean comparison. These operators are listed in Table 1-3. Table 1-3 Boolean Operators Operator Description -not Not! Not -and And -or Or Listing 1-22 has a sample of the If Elseif Else operator. It allows you to control actions that occur in your script. Notice that test arguments are enclosed in parentheses, and braces { } are used for the commands related to each portion of the If. Listing 1-22 If Statement $a = 5 $b = If ($a gt $b) { $c = $a } Elseif ($b gt $a) { $c = $b } Else { $c = $a + $b } Write-Host $c The equivalent statement to VBScript s Select Case is the Switch statement. This statement starts with the variable that you are comparing and then the list actions to perform at each matching value. If no values are matched, no action is taken, but you are allowed to use a default action as a catchall if you would like in Listing 1-23.

27 Getting More Power with PowerShell BC27 Listing 1-23 Switch Statement $Name = Bobby Switch ($Name) { Jane {Write-Host $Name is awesome. } Judy {Write-Host $Name is great. } Bobby {Write-Host $Name is the best. } default { $Name, I am not familiar with that person } } Loops To allow you to perform steps a repeated number of times, several options are available to you. Here are the most common types of loops you will use in PowerShell. Do While The main looping structure in PowerShell is Do. Do identifies the start of the looping structure, which continues through a pair of braces. At the end of the braces, you find the While condition. The loop will always process once with the evaluation to repeat the process being made at the end. When the contention is true, looping continues. Listing 1-24 shows a Do While loop. Listing 1-24 $i = 1 Do { Write-Host $i $i++ } While ($i le 5) Do While Loop Notice the $i++ found in this code; this is shorthand that was used with C++. This is short for $i = $i + 1. If you need to perform the reverse calculation, $i = $i -1, you can use the $i-- shorthand. Do Until Similar to the previous loop, the loop in Listing 1-25 repeats until the conditions are met.

28 BC28 Getting More Power with PowerShell Listing 1-25 Do Until Loop $i = 1 Do { Write-Host $i $i++ } Until ($i gt 5) The only difference between Do While and Do Until is that your criteria for evaluation is reversed between the While and Until loops. While these two loops have used a countermechanism, any logic test could have been used to exit the loop, such as the length of a string or a variable containing a certain value. For The For loop repeats through a process for a fixed number of iterations. In this case, the criteria puts all the loop logic into a single block of logic associated with the For command. The block ($i=1;$i -le 5;$i++) has three commands that perform the same counter functions that were used in the previous two loops. First you set $i to 1, you evaluate to see whether $i is less than or equal to 5, and then you add 1 to the value of $i. As long as $i is less than or equal to 5, you perform the actions within the braces, as illustrated in Listing Listing 1-26 For Loop For ($i=1;$i -le 5;$i++) {Write-Host $i} ForEach As the name suggests, the ForEach loop performs an action for each item that exists in an array or a collection. In Listing 1-27, you use the Get- Process cmdlet to get a collection of process objects, which you can then perform an action upon. Listing 1-27 For Each Loop ForEach ($item in Get-Process) {Write-Host $Item.Name} Screen output Getting a PowerShell script to report information is quite easy. You have four basic methods of getting a script to write information to a location:

29 Getting More Power with PowerShell BC29 Quote a string Write-Output command Redirect symbol Write-Host The easiest is to have a script generate output is to put a quoted string on a line of the script, which will cause that to be outputted on the screen. To report a variable or a string with a variable embedded simply put them on alone on a line your script. Listing 1-28 is an example of these commands. Notice that you simply put the variable inside the string, whereas in VBScript, you needed to concatenate the text and variables together. Listing 1-28 Outputting to the Screen My Name $strmyname = Ed Tetz $strmyname My name is $strmyname This output will show up on the screen or wherever stdout (standard output) is set to display output. The other way to get data sent to stdout is with the Write-Output command: Write-Output $strmyname Rather than having the data sent to the screen, you can have stdout redirect data to a file by using the redirect symbol (>). This can be done for specific commands or for an entire script. Here are a couple of examples: C:\Temp\MyScript.ps1 > C:\Temp\Output1.txt My name is $strmyname > C:\Temp\Output2.txt When redirecting output to an alternate location, you can use Write-Host, which will force output to the screen: Write-Host $strmyname Opening and saving files Rather than using redirection, you may also use the Out-File command to specifically write data to a file. Here you use the Out-File command to save the output from the Get-Processes command by passing the data through a pipe: Get-Processes Out-File C:\Temp\Processes.txt

30 BC30 Getting More Power with PowerShell If you want to append to a file, if it already exists, rather than overwriting the file, you will use the Append option: Get-Processes Out-File Append C:\Temp\Processes.txt The NoClobber option is a little different; it says that if the file already exists, do not overwrite the file. In this case, the original file will remain intact and the new file will not be saved: Get-Processes Out-File NoClobber C:\Temp\Processes.txt Like the Out-File command, the Export-Csv command sends output to a file, but in this case, it will be a comma-separated values (.csv) file, which can then be opened in Microsoft Excel or Notepad: Get-Processes Export-Csv C:\Temp\Processes.csv Getting data from a file is easy with PowerShell. The Get-Content command allows you to read the contents of a file and treat the content as a collection. Listing 1-29 has you put the content of the file into a collection named $Names: Listing 1-29 Getting Content from Files $Names = Get-Content C:\Temp\Names of People.txt ForEach($Name In $Names) { Switch ($Name) { Jane {Write-Host $Name is awesome. } Judy {Write-Host $Name is great. } Bobby {Write-Host $Name is the best. } default { $Name, I am not familiar with that person } } } Because you were able to export data to a CSV file, it is good to know that you are able to get data in from a CSV file. The Import-Csv command reads data in from the file and allows you to use it immediately: Import-Csv C:\Temp\Processes.csv Working with parameters When you create a script, you may want to reuse it by using arguments (also called parameters). To use arguments when calling scripts, you only need to