Programming the Windows Script Host

This chapter is from the book

Microsoft Windows Vista Unleashed, 2nd Edition

Learn More Buy

This chapter is from the book

This chapter is from the book 

Microsoft Windows Vista Unleashed, 2nd Edition

Learn More Buy

Programming the WshShell Object

WshShell is a generic name for a powerful object that enables you to query and interact with various aspects of the Windows shell. You can display information to the user, run applications, create shortcuts, work with the Registry, and control Windows' environment variables. The next few sections discuss each of those useful tasks.

Referencing the WshShell Object

WshShell refers to the Shell object exposed via the Automation interface of WScript. Therefore, you must use CreateObject to return this object:

Set objWshShell = WScript.CreateObject("WScript.Shell")

From here, you can use the objWshShell variable to access the object's properties and methods.

Displaying Information to the User

You saw earlier that the WScript object's Echo method is useful for displaying simple text messages to the user. You can gain more control over the displayed message by using the WshShell object's Popup method. This method is similar to the MsgBox function used in Visual Basic and VBA in that it enables you to control both the dialog box title and the buttons displayed, as well as to determine which of those buttons the user pressed. Here's the syntax:

WshShell.Popup(strText, [nSecondsToWait], [strTitle], [intType])

For example, the following statements display the dialog box shown in Figure 12.2:

Set objWshShell = WScript.CreateObject("WScript.Shell")
objWshShell.Popup "Couldn't find Memo.doc!", , "Warning"

Figure 12.2 A simple message dialog box produced by the Popup method.

WshShell.Popup "First line" & Chr(13) & "Second line"

WshShell.Popup("First line" + "\n" + "Second line");

Setting the Style of the Message

The default Popup dialog box displays only an OK button. You can include other buttons and icons in the dialog box by using different values for the intType parameter. Table 12.1 lists the available options.

Table 12.1. The Popup Method's intType Parameter Options

You derive the intType argument in one of two ways:

• By adding the values for each option
• By using the VBScript constants separated by plus signs (+)

The script in Listing 12.4 shows an example and Figure 12.3 shows the resulting dialog box.

Figure 12.3 The dialog box that's displayed when you run the script.

Listing 12.4. A VBScript Example That Uses the Popup Method to Display the Dialog Box Shown in Figure 12.3

' First, set up the message
'
strText = "Are you sure you want to copy" & Chr(13)
strText = strText & "the selected files to drive A?"
strTitle = "Copy Files"
intType = vbYesNoCancel + vbQuestion + vbDefaultButton2
'
' Now display it
'
Set objWshShell = WScript.CreateObject("WScript.Shell")
intResult = objWshShell.Popup(strText, ,strTitle, intType)

Here, three variables—strText, strTitle, and intType—store the values for the Popup method's strText, strTitle, and intType arguments, respectively. In particular, the following statement derives the intType argument:

intType = vbYesNoCancel + vbQuestion + vbDefaultButton2

You also could derive the intType argument by adding up the values that these constants represent (3, 32, and 256, respectively), but the script becomes less readable that way.

Getting Return Values from the Message Dialog Box

A dialog box that displays only an OK button is straightforward. The user either clicks OK or presses Enter to remove the dialog from the screen. The multibutton styles are a little different, however; the user has a choice of buttons to select, and your script should have a way to find out which button the user chose, which enables it to decide what to do next, based on the user's selection. You do this by storing the Popup method's return value in a variable. Table 12.2 lists the seven possible return values.

Table 12.2. The Popup Method's Return Values

To process the return value, you can use an If...Then...Else or Select Case structure to test for the appropriate values. For example, the script shown earlier used a variable called intResult to store the return value of the Popup method. Listing 12.5 shows a revised version of the script that uses a VBScript Select Case statement to test for the three possible return values.

Listing 12.5. A Script That Uses a Select Case Statement to Process the Popup Method's Return Value

' First, set up the message
'
strText = "Are you sure you want to copy" & Chr(13)
strText = strText & "the selected files to drive A?"
strTitle = "Copy Files"
intType = vbYesNoCancel + vbQuestion + vbDefaultButton2
'
' Now display it
'
Set objWshShell = WScript.CreateObject("WScript.Shell")
intResult = objWshShell.Popup(strText, ,strTitle, intType)
'
' Process the result
'
Select Case intResult
    Case vbYes
        WScript.Echo "You clicked ""Yes""!"
    Case vbNo
        WScript.Echo "You clicked ""No""!"
    Case vbCancel
        WScript.Echo "You clicked ""Cancel""!"
End Select

Running Applications

When you need your script to launch another application, use the Run method:

WshShell.Run strCommand, [intWindowStyle], [bWaitOnReturn]

Here's an example:

Set objWshShell = WScript.CreateObject("WScript.Shell")
objWshShell.Run "Control.exe Inetcpl.cpl", 1, True

This Run method launches Control Panel's Internet Properties dialog box.

Working with Shortcuts

The Windows Script Host enables your scripts to create and modify shortcut files. When writing scripts for other users, you might want to take advantage of this capability to display shortcuts for new network shares, Internet sites, instruction files, and so on.

Creating a Shortcut

To create a shortcut, use the CreateShortcut method:

WshShell.CreateShortcut(strPathname)

The following example creates and saves a shortcut on a user's desktop:

Set WshShell = objWScript.CreateObject("WScript.Shell")
Set objShortcut = objWshShell.CreateShortcut("C:\Users\Paul\Desktop\test.lnk")
objShortcut.Save

Programming the WshShortcut Object

The CreateShortcut method returns a WshShortcut object. You can use this object to manipulate various properties and methods associated with shortcut files.

This object contains the following properties:

• Arguments—Returns or sets a string that specifies the arguments used when launching the shortcut. For example, suppose that the shortcut's target is the following:

  C:\Windows\Notepad.exe C:\Boot.ini

  In other words, this shortcut launches Notepad and loads the Boot.ini file. In this case, the Arguments property would return the following string:

  C:\Boot.ini

• Description—Returns or sets a string description of the shortcut.
• FullName—Returns the full path and filename of the shortcut's target. This will be the same as the strPathname value used in the CreateShortcut method.
• Hotkey—Returns or sets the hotkey associated with the shortcut. To set this value, use the following syntax:

  WshShortcut.Hotkey = strHotKey

  WshShortcut	The WshShortcut object.
  strHotKey	A string value of the form Modifier+Keyname, where Modifier is any combination of Alt, Ctrl, and Shift, and Keyname is one of A through Z or 0 through 12.

  For example, the following statement sets the hotkey to Ctrl+Alt+7:

  objShortcut.Hotkey = "Ctrl+Alt+7"

• IconLocation—Returns or sets the icon used to display the shortcut. To set this value, use the following syntax:

  WshShortcut.IconLocation = strIconLocation

  WshShortcut	The WshShortcut object.
  strIconLocation	A string value of the form Path,Index, where Path is the full pathname of the icon file and Index is the position of the icon within the file (where the first icon is 0).

  Here's an example:

  objShortcut.IconLocation = "C:\Windows\System32\Shell32.dll,21"

• TargetPath—Returns or sets the path of the shortcut's target.
• WindowStyle—Returns or sets the window style used by the shortcut's target. Use the same values outlined earlier for the Run method's intWindowStyle argument.
• WorkingDirectory—Returns or sets the path of the shortcut's working directory.

The WshShortcut object also supports two methods:

• Save—Saves the shortcut file to disk.
• Resolve—Uses the shortcut's TargetPath property to look up the target file. Here's the syntax:

  WshShortcut.Resolve = intFlag

  WshShortcut	The WshShortcut object.
  intFlag	Determines what happens of the target file is not found:

  intFlag	What Happens
  1	Nothing
  2	Windows continues to search subfolders for the target file
  4	Updates the TargetPath property if the target file is found in a new location

Listing 12.6 shows a complete example of a script that creates a shortcut.

Listing 12.6. A Script That Creates a Shortcut File

Set objWshShell = WScript.CreateObject("WScript.Shell")
Set objShortcut = objWshShell.CreateShortcut("C:\Users\Paul\Desktop\Edit BOOT.INI.lnk")
With objShortcut
    .TargetPath = "C:\Windows\Notepad.exe "
    .Arguments = "C:\Boot.ini"
    .WorkingDirectory = "C:\"
    .Description = "Opens BOOT.INI in Notepad"
    .Hotkey = "Ctrl+Alt+7"
    .IconLocation = "C:\Windows\System32\Shell32.dll,21"
    .WindowStyle = 3
    .Save
End With

Working with Registry Entries

You've seen throughout this book that the Registry is one the most crucial data structures in Windows. However, the Registry isn't a tool that only Windows yields. Most 32-bit applications make use of the Registry as a place to store setup options, customization values the user selected, and much more. Interestingly, your scripts can get in on the act as well. Not only can your scripts read the current value of any Registry setting, but they can also use the Registry as a storage area. This enables you to keep track of user settings, recently used files, and any other configuration data that you'd like to save between sessions. This section shows you how to use the WshShell object to manipulate the Registry from within your scripts.

Reading Settings from the Registry

To read any value from the Registry, use the WshShell object's RegRead method:

WshShell.RegRead(strName)

The script in Listing 12.7 displays the name of the registered owner of this copy of Windows XP.

Listing 12.7. A Script That Reads the RegisteredOwner Setting from the Registry

Set objWshShell = WScript.CreateObject("WScript.Shell")
strSetting = "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\RegisteredOwner"
strRegisteredUser = objWshShell.RegRead(strSetting)
WScript.Echo strRegisteredUser

Storing Settings in the Registry

To store a setting in the Registry, use the WshShell object's RegWrite method:

WshShell.RegWrite strName, anyValue [, strType]

The following statements create a new key named ScriptSettings in the HKEY_CURRENT_USER root:

Set objWshShell = WScript.CreateObject("WScript.Shell")
objWshShell.RegWrite "HKCU\ScriptSettings\", ""

The following statements create a new value named NumberOfReboots in the HKEY_CURRENT_USER\ScriptSettings key, and set this value to 1:

Set objWshShell = WScript.CreateObject("WScript.Shell")
objWshShell.RegWrite "HKCU\ScriptSettings\NumberOfReboots", 1, "REG_DWORD"

Deleting Settings from the Registry

If you no longer need to track a particular key or value setting, use the RegDelete method to remove the setting from the Registry:

WshShell.RegDelete(strName)

To delete the NumberOfReboots value used in the previous example, you would use the following statements:

Set objWshShell = WScript.CreateObject("WScript.Shell")
objWshShell.RegDelete "HKCU\ScriptSettings\NumberOfReboots"

Working with Environment Variables

Windows Vista keeps track of a number of environment variables that hold data such as the location of the Windows folder, the location of the temporary files folder, the command path, the primary drive, and much more. Why would you need such data? One example would be for accessing files or folders within the main Windows folder. Rather than guessing that this folder is C:\Windows, it would be much easier to just query the %SystemRoot% environment variable. Similarly, if you have a script that accesses files in a user's My Documents folder, hard-coding the username in the file path is inconvenient because it means creating custom scripts for every possible user. Instead, it would be much easier to create just a single script that references the %UserProfile% environment variable. This section shows you how to read environment variable data within your scripts.

The defined environment variables are stored in the Environment collection, which is a property of the WshShell object. Windows Vista environment variables are stored in the "Process" environment, so you reference this collection as follows:

WshShell.Environment("Process")

Listing 12.8 shows a script that runs through this collection, adds each variable to a string, and then displays the string.

Listing 12.8. A Script That Displays the System's Environment Variables

Set objWshShell = WScript.CreateObject("WScript.Shell")
'
' Run through the environment variables
'
strVariables = ""
For Each objEnvVar In objWshShell.Environment("Process")
    strVariables = strVariables & objEnvVar & Chr(13)
Next
WScript.Echo strVariables

Figure 12.4 shows the dialog box that appears (your mileage may vary).

Figure 12.4 A complete inventory of a system's environment variables.

If you want to use the value of a particular environment variable, use the following syntax:

WshShell.Environment("Process")("strName")

Listing 12.9 shows a revised version of the script from Listing 12.6 to create a shortcut. In this version, the Environment collection is used to return the value of the %UserProfile% variable, which is used to contrast the path to the current user's Desktop folder.

Listing 12.9. A Script That Creates a Shortcut File Using an Environment Variable

Set objWshShell = WScript.CreateObject("WScript.Shell")
strUserProfile = objWshShell.Environment("Process")("UserProfile")
Set objShortcut = objWshShell.CreateShortcut(strUserProfile & _
                  "\Desktop\Edit BOOT.INI.lnk")
With objShortcut
    .TargetPath = "C:\Windows\Notepad.exe "
    .Arguments = "C:\Boot.ini"
    .WorkingDirectory = "C:\"
    .Description = "Opens BOOT.INI in Notepad"
    .Hotkey = "Ctrl+Alt+7"
    .IconLocation = "C:\Windows\System32\Shell32.dll,21"
    .WindowStyle = 3
    .Save
End With