With the VBScript solutions, my intention is to provide the answer in as few lines of code as is reasonable. Since this book is not a pure programming book, I did not want to overshadow the graphical and command-line solutions by providing pages of code or detailed explanations on how to use WSH, WMI, or ADSI. If you are looking for such material, I recommend my book Active Directory Cookbook (O'Reilly) or Windows 2000 Scripting Guide by Microsoft Corporation (MSPress). The code in this book is meant to show you the basics for how a task can be automated and let you run with it. Most examples will take only minor tweaking to make them do something useful in your environment.
To make the code as simple as possible, I had to remove error checking and other features that are standard scripting best practices. Next, I'll describe how to incorporate these things into your own scripts so that you can quickly turn any code in this book into a robust script with all the trimmings.
Just as you might need to run the graphical and command-line tools with alternate credentials, you may also need to run your scripts and programs with alternate credentials. One way is to use the runas utility when you invoke a script from the command line. Another option is to use the Scheduled Tasks service to run the script under credentials you specify when creating the scheduled task. And yet another option is to hardcode the credentials in the script. Obviously this is not very appealing in many scenarios because you do not want the username and password contained in the script to be easily viewable by others. Nevertheless, at times it is a necessary evil, especially when working against multiple servers, and I'll describe how it can be done with WMI, ADSI, and ADO.
Here is example WMI code that prints the list of disk drives on a system:
strComputer = "." ' localhost set objWMI = GetObject("winmgmts:\\" & strComputer & "\root\cimv2") set objDisks = objWMI.InstancesOf("Win32_LogicalDisk") for each objDisk in objDisks Wscript.Echo "DeviceID: " & objDisk.DeviceID Wscript.Echo "FileSystem: " & objDisk.FileSystem Wscript.Echo "FreeSpace: " & objDisk.FreeSpace Wscript.Echo "Size: " & objDisk.Size WScript.Echo "" next
This code does the same thing, except it targets a remote computer (srv01) and authenticates as the administrator account on that system:
set objLocator = CreateObject("WbemScripting.SWbemLocator") set objWMI = objLocator.ConnectServer("srv01", "root\cimv2", _ "srv01\administrator", "Adm1nPa33wd") set objDisks = objWMI.InstancesOf("Win32_LogicalDisk") for each objDisk in objDisks Wscript.Echo "DeviceID: " & objDisk.DeviceID Wscript.Echo "FileSystem: " & objDisk.FileSystem Wscript.Echo "FreeSpace: " & objDisk.FreeSpace Wscript.Echo "Size: " & objDisk.Size WScript.Echo "" next
To authenticate as an alternate user in WMI, you simply need
to replace the
with two statements. The first is a call to
CreateObject, which instantiates a
SWbemLocator object. With this
object, you can then call the
ConnectServer method and specify the
credentials for authentication. The first parameter is the server
name, the second is the WMI provider path, the third is the user,
and the fourth is the user's password.
With ADSI, you can use the
IADsOpenDSObject::OpenDSObject method to
specify alternate credentials. For example, a solution to print out
the description of a domain might look like the following:
set objDomain = GetObject("LDAP://dc=rallencorp,dc=com") WScript.Echo "Description: " & objDomain.Get("description")
takes only one additional statement to make the same code
authenticate as the administrator account in the domain.
set objLDAP = GetObject("LDAP:") set objDomain = objLDAP.OpenDSObject( _ "LDAP://dc=rallencorp,dc=com", _ "email@example.com", _ "MyPassword", _ 0) WScript.Echo "Description: " & objDomain.Get("description")
It is just as easy to authenticate in ADO code. Take the
following example, which queries all
computer objects in the rallencorp.com domain:
strBase = "<LDAP://dc=rallencorp,dc=com>;" strFilter = "(&(objectclass=computer)(objectcategory=computer));" strAttrs = "cn;" strScope = "subtree" set objConn = CreateObject("ADODB.Connection") objConn.Provider = "ADsDSOObject" objConn.Open "Active Directory Provider" set objRS = objConn.Execute(strBase & strFilter & strAttrs & strScope) objRS.MoveFirst while Not objRS.EOF Wscript.Echo objRS.Fields(0).Value objRS.MoveNext wend
Now, by adding two lines (shown in bold), we can authenticate with the administrator account:
strBaseDN = "<LDAP://dc=rallencorp,dc=com>;" strFilter = "(&(objectclass=computer)(objectcategory=computer));" strAttrs = "cn;" strScope = "subtree" set objConn = CreateObject("ADODB.Connection") objConn.Provider = "ADsDSOObject"
objConn.Properties("User ID") = "firstname.lastname@example.org"
objConn.Properties("Password") = "MyPassword"objConn.Open "Active Directory Provider" set objRS = objConn.Execute(strBaseDN & strFilter & strAttrs & strScope) objRS.MoveFirst while Not objRS.EOF Wscript.Echo objRS.Fields(0).Value objRS.MoveNext wend
To authenticate with ADO, you need to set the
Password properties of the
ADO connection object. I used the user principal name (UPN) of the
administrator for the user ID in this example. Active Directory
allows connections with a UPN (email@example.com), NT
4.0-style account name (e.g., RALLENCORP\Administrator), or
distinguished name (e.g., cn=administrator,cn=users,dc=ral-lencorp,dc=com)
for the user ID.
An important part of any script is error checking. Error checking allows your programs to gracefully identify any issues that arise during execution and take appropriate action. Another good practice when writing scripts is to define variables before you use them and clean them up after you are done with them. In this book, most of the programmatic solutions do not include any error checking, predefined variables, or variable clean up. While admittedly this does not set a good example, if I included extensive error checking and variable management, it would have made this book considerably longer with little value to you, the reader.
Error checking with VBScript is pretty straightforward. At the beginning of the script, include the following declaration:
On Error Resume Next
This tells the script interpreter to continue even if errors
occur. Without that declaration, whenever an error is encountered, the
script will abort. When you use
Resume Next, you need to use the
Err object to check for errors after any
step where a fatal error could occur. The following example shows how
to use the
On Error Resume Next set objDomain = GetObject("LDAP://dc=rallencorp,dc=com") if Err.Number <> 0 then Wscript.Echo "An error occured getting the domain object: " & Err.Description Wscript.Quit end if
Two important properties of the
Err object are
Number, which if nonzero signifies an error,
Description which contains the
error message (when present).
As far as variable management goes, it is always a good practice to include the following at the beginning of every script:
When this is used, every variable in the script must be declared
or an exception will be generated when you attempt to run the script.
This prevents a mistyped name from causing hard-to-trace errors.
Variables are declared in VBScript using the
Dim keyword. After you are done with a
variable, it is a good practice to set it to
Nothing so you release any resources bound
to the variable, and don't accidentally reuse the variable with its
previous value. The following code shows a complete example for
printing the display name for a domain with error checking and
variable management included:
Option Explicit On Error Resume Next Dim objDomain set objDomain = GetObject("LDAP://cn=users,dc=rallencorp,dc=com") if Err.Number <> 0 then Wscript.Echo "An error occured getting the domain object: " & Err.Description Wscript.Quit end if Dim strDescr strDescr = objDomain.Get("description") if Err.Number <> 0 then Wscript.Echo "An error occured getting the description: " & Err.Description Wscript.Quit end if WScript.Echo "Description: " & strDescr set objDomain = Nothing set strDescr = Nothing
Most code samples you'll see in this book use hardcoded variables. That means when you want to change the value of a variable, you have to modify the script. A much more flexible solution is to obtain the desired value of those variables via command-line options. All good command-line programs work this way.
With WSH, you can retrieve the command-line options that are
passed to a script by enumerating the
WScript.Arguments object. Here is an
set objArgs = WScript.Arguments WScript.Echo "Total number of arguments: " & WScript.Arguments.Count for each strArg in objArgs WScript.Echo strArg next
This works OK, but there is no structure to it. You can't
retrieve the value of the
option by name. You can only access elements of a
WScript.Arguments collection by index
number. But never fear, WSH 5.6 introduced named and unnamed
arguments. Let's say we invoked the following command:
> d:\scripts\dostuff.vbs /c:test /verbose:4
This bit of code shows how you can access the
WScript.Echo WScript.Arguments.Named.Item("c") WScript.Echo WScript.Arguments.Named.Item("verbose")
In most of the code in this book, I simply print the output to STDOUT using the
WScript.Echo method. This is OK if
you need an interactive script, but what if you want to schedule one
to run periodically? Printing the output to STDOUT won't do much good.
An alternative is to write the output to a file instead. This is
pretty easy using WSH. The following code appends some text to a
' ------ SCRIPT CONFIGURATION ------ strFile = "
<FilePath>" ' e.g. c:\output.txt ' ------ END CONFIGURATION --------- const ForAppending = 8 set objFSO = CreateObject("Scripting.FileSystemObject") set objFile = objFSO.OpenTextFile(strFile, constForAppending, True) objFile.WriteLine("Script completed: " & Now) objFile.Close
There is nothing magical here. The
Scripting.FileSystemObject interface is used
for working with files. The
OpenTextFile method supports different
access options. The following script is a variation of the earlier
script except it opens a file for writing out all of the running
processes (overwriting any existing data in the file):
' ------ SCRIPT CONFIGURATION ------ strFile = "
<FilePath>" ' e.g. c:\output.txt ' ------ END CONFIGURATION --------- constForWriting = 2 set objFSO = CreateObject("Scripting.FileSystemObject") set objFile = objFSO.OpenTextFile(strFile, constForWriting, True) objFile.WriteLine("Script started: " & Now) objFile.WriteLine("List of processes:") set objWMI = GetObject("winmgmts:root\cimv2") for each objProcess in objWMI.InstancesOf("Win32_Process") objFile.WriteLine(vbTab & objProcess.Name) next objFile.WriteLine("Script completed: " & Now) objFile.Close
have to use the
WriteLine method of
object. If you also wanted to print the results to STDOUT, there is
nothing to prevent you from putting a
WScript.Echo statement right before or after
When you automate a task, you are being proactive. Part of being proactive is trying to identify issues before they turn into major problems. If your scripts simply append their status to a log file, it is unlikely you'll learn about any problems in a timely manner unless you are vigilantly watching over your log files. Fortunately, you can send emails very easily from VBScript so that instead of writing to a file, you can choose to send an email when there is a serious issue.
Here is an example script that just sends simple email:
' This code sends an email via SMTP ' ------ SCRIPT CONFIGURATION ------ strFrom = "firstname.lastname@example.org" strTo = "email@example.com" strSub = "Script Output" strBody = "The script ran successfully" strSMTP = "smtp.rallencorp.com" ' ------ END CONFIGURATION --------- set objEmail = CreateObject("CDO.Message") objEmail.From = strFrom objEmail.To = strTo objEmail.Subject = strSub objEmail.Textbody = strBody objEmail.Configuration.Fields.Item( _ "http://schemas.microsoft.com/cdo/configuration/sendusing") = 2 objEmail.Configuration.Fields.Item( _ "http://schemas.microsoft.com/cdo/configuration/smtpserver") = _ strSMTP objEmail.Configuration.Fields.Update objEmail.Send WScript.Echo "Email sent"
This code requires the use of a SMTP-enabled mail server. The email is directed toward the mail server, which relays it to the correct destination. This script also requires Microsoft Collaboration Data Objects (CDO) to be installed on the client computer. This can be done by installing Outlook or by installing CDO separately from the Microsoft site (search for "CDO" on http://msdn.microsoft.com/).
A common question I see on newsgroups has to do with reading and writing Excel spreadsheets from scripts. Why would you want to do this, you might ask? Well, let's suppose that I manage over 20 servers. I put together a small spreadsheet to keep track of them. Now, if I want to perform a task on all of my servers with a script, all I need to do is read information about each of the servers from the Excel spreadsheet and I don't have to worry about hardcoding the servers within the script.
This next script shows how to iterate over the rows in a worksheet until the script comes across a row that does not have the first cell populated:
' ------ SCRIPT CONFIGURATION ------ strExcelPath = "c:\data.xls" intStartRow = 2 ' ------ END CONFIGURATION --------- On Error Resume Next set objExcel = CreateObject("Excel.Application") if Err.Number <> 0 then Wscript.Echo "Excel application not installed." Wscript.Quit end if On Error GoTo 0 objExcel.WorkBooks.Open strExcelPath set objSheet = objExcel.ActiveWorkbook.Worksheets(1) intRow = intStartRow do while objSheet.Cells(intRow, 1).Value <> "" WScript.Echo "Row " & intRow WScript.Echo "Cell 1: " & objSheet.Cells(intRow, 1).Value WScript.Echo "Cell 2: " & objSheet.Cells(intRow, 2).Value WScript.Echo "Cell 3: " & objSheet.Cells(intRow, 3).Value WScript.Echo "Cell 4: " & objSheet.Cells(intRow, 4).Value intRow = intRow + 1 WScript.Echo loop objExcel.ActiveWorkbook.Close objExcel.Application.Quit Wscript.Echo "Done"
In this case, I just printed the values from the first four cells. You could obviously do more complex stuff with that information.
Now suppose I wanted to analyze the process information of a system. I could use the taskmgr.exe program, but it doesn't really give me the flexibility I need. Instead I can write a script to output that information to a spreadsheet. Here is the code to do that:
' ------ SCRIPT CONFIGURATION ------ strComputer = "." strExcelPath = "d:\procs.xls" ' ------ END CONFIGURATION --------- On Error Resume Next set objExcel = CreateObject("Excel.Application") if Err.Number <> 0 then Wscript.Echo "Excel application not installed." Wscript.Quit end if On Error GoTo 0 ' Create a new workbook. objExcel.Workbooks.Add ' Bind to worksheet. Set objSheet = objExcel.ActiveWorkbook.Worksheets(1) objSheet.Name = "Processes" ' Populate spreadsheet cells with user attributes. objSheet.Cells(1, 1).Value = "Process Name" objSheet.Cells(1, 2).Value = "Command Line" objSheet.Cells(1, 3).Value = "PID" objSheet.Cells(1, 4).Value = "Owner" objSheet.Range("A1:D1").Font.Bold = True ' Query process information set objWMI = GetObject("winmgmts:\\" & strComputer & "\root\cimv2") intProcessCount = 1 for each objProcess in objWMI.InstancesOf("Win32_Process") ' For each process, write the name, command-line options and process ID ' to the spreadsheet intProcessCount = intProcessCount + 1 objSheet.Cells(intProcessCount,1).Value = objProcess.Name objSheet.Cells(intProcessCount,2).Value = ObjProcess.CommandLine objSheet.Cells(intProcessCount,3).Value = ObjProcess.ProcessID objProcess.GetOwner strUser,strDomain objSheet.Cells(intProcessCount,4).Value = strDomain & "\" & strUser next ' This formats the columns objExcel.Columns(1).ColumnWidth = 20 objExcel.Columns(2).ColumnWidth = 50 objExcel.Columns(3).ColumnWidth = 5 objExcel.Columns(4).ColumnWidth = 30 ' Save the spreadsheet, close the workbook and exit. objExcel.ActiveWorkbook.SaveAs strExcelPath objExcel.ActiveWorkbook.Close objExcel.Application.Quit WScript.Echo "Done"
I included comments in the code to help you follow along with what is happening. Pretty straightforward, isn't it? Keep in mind that Excel must be installed on the computer in order to run this script.