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WMI Tasks: Event Logs

WMI tasks for event logs obtain event data from event log files and perform operations like backing up or clearing log files. For other examples, see the TechNet ScriptCenter at http://www.microsoft.com/technet.

The script examples shown in this topic obtain data only from the local computer. For more information about how to use the script to obtain data from remote computers, see Connecting to WMI on a Remote Computer.

The following procedure describes how to run a script.

Aa394593.wedge(en-us,VS.85).gifTo run a script

  1. Copy the code and save it in a file with a .vbs extension. Ensure that your text editor does not add a .txt extension to the file.
  2. Open a command prompt window and navigate to the directory where you saved the file.
  3. Type cscript scriptfile.vbs at the command prompt.

Note  By default, cscript displays the output of a script in the command prompt window. Because WMI scripts can produce large amounts of output, you might want to redirect the output to a file. Type cscript scriptfile.vbs > outfile.txt at the command prompt to redirect the output of the filename.vbs script to outfile.txt.

The following table lists script examples that can be used to obtain various types of data from the local computer.

How do I...WMI classes or methods
...retrieve information about the Security event log?Include the Security privilege when connecting to the Win32_NTEventlogFile class. For more information, see Executing Privileged Operations Using VBScript.
strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
    & "{impersonationLevel=impersonate,(Security)}!\\" & _
        strComputer & "\root\cimv2")
Set colLogFiles = objWMIService.ExecQuery _
    ("Select * from Win32_NTEventLogFile " _
        & "Where LogFileName='Security'")
For Each objLogFile in colLogFiles
    Wscript.Echo objLogFile.NumberOfRecords
    Wscript.Echo "Maximum Size: " _
    &  objLogfile.MaxFileSize 
Next
...back up an event log?Use the Win32_NTEventlogFile class and the BackupEventLog method. You may need to include the Backup privilege when connecting to WMI. For more information, see Executing Privileged Operations Using VBScript.
strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
    & "{impersonationLevel=impersonate,(Backup)}!\\" & _
        strComputer & "\root\cimv2")
Set colLogFiles = objWMIService.ExecQuery _
    ("Select * from Win32_NTEventLogFile " _
        & "Where LogFileName='Application'")
For Each objLogfile in colLogFiles
    errBackupLog = objLogFile.BackupEventLog( _
        "c:\scripts\application.evt")
    WScript.Echo "File saved as c:\scripts\applications.evt"
Next
...back up an event log more than once?Ensure that the backup file has a unique name before using the Win32_NTEventlogFile and the BackupEventLog method. The operating system does not allow you to overwrite an existing backup file; you must either move the backup file or rename it before you can run the script again. You may need to include the Backup privilege when connecting to WMI. For more information, see Executing Privileged Operations Using VBScript.
dtmThisDay = Day(Date)
dtmThisMonth = Month(Date)
dtmThisYear = Year(Date)
strBackupName = dtmThisYear & "_" & dtmThisMonth _
    & "_" & dtmThisDay
strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
    & "{impersonationLevel=impersonate,(Backup)}!\\" & _
        strComputer & "\root\cimv2")
Set colLogFiles = objWMIService.ExecQuery _
    ("Select * from Win32_NTEventLogFile " _
        & "Where LogFileName='Application'")
For Each objLogfile in colLogFiles
    objLogFile.BackupEventLog("c:\scripts\" _
        & strBackupName & _
        "_application.evt")
    objLogFile.ClearEventLog()
    WScript.Echo "File saved: " & strBackupName & _
        "_application.evt"
Next
...determine the number of records in an event log?Use the Win32_NTEventlogFile class and check the value of the NumberOfRecords property.
strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
    & "{impersonationLevel=impersonate}!\\" _
    & strComputer & "\root\cimv2")
Set colLogFiles = objWMIService.ExecQuery _
    ("Select * from Win32_NTEventLogFile " _
    & "Where LogFileName='System'")
For Each objLogFile in colLogFiles
    Wscript.Echo objLogFile.NumberOfRecords
Next
...clear my event logs?Use the Win32_NTEventlogFile class and the ClearEventLog method.
strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
    & "{impersonationLevel=impersonate,(Backup)}!\\" & _
        strComputer & "\root\cimv2")
Set colLogFiles = objWMIService.ExecQuery _
    ("Select * from Win32_NTEventLogFile " _
    & "Where LogFileName='Application'")
For Each objLogfile in colLogFiles
    objLogFile.ClearEventLog()
    WScript.Echo "Cleared application event log file"
Next
...read events from the event logs?Use the Win32_NTLogEvent class.
strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
    & "{impersonationLevel=impersonate}!\\" _
    & strComputer & "\root\cimv2")
Set colLoggedEvents = objWMIService.ExecQuery _
    ("Select * from Win32_NTLogEvent " _
        & "Where Logfile = 'System'")
For Each objEvent in colLoggedEvents
    Wscript.Echo "Category: " & objEvent.Category & VBNewLine _
    & "Computer Name: " & objEvent.ComputerName & VBNewLine _
    & "Event Code: " & objEvent.EventCode & VBNewLine _
    & "Message: " & objEvent.Message & VBNewLine _
    & "Record Number: " & objEvent.RecordNumber & VBNewLine _
    & "Source Name: " & objEvent.SourceName & VBNewLine _
    & "Time Written: " & objEvent.TimeWritten & VBNewLine _
    & "Event Type: " & objEvent.Type & VBNewLine _
    & "User: " & objEvent.User
Next

 

Related topics

WMI Tasks for Scripts and Applications
WMI C++ Application Examples
TechNet ScriptCenter

 

 

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