File monitor

[kadara]

Hi,
I would like to monitor a text file. Currently I use the following code:

strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")

'Set colMonitoredEvents = objWMIService.ExecNotificationQuery _
'    ("SELECT * FROM __InstanceModificationEvent WITHIN 1 WHERE " _
'        & "TargetInstance ISA 'CIM_DataFile' and " _
'            & "TargetInstance.Name='U:\\Programming\\Hydra\\Label\\LogFile01.txt'")

strPnrPath01 = "U:\\Programming\\Test05\\Test01.txt"

Set colMonitoredEvents = objWMIService.ExecNotificationQuery _
    ("SELECT * FROM __InstanceOperationEvent WITHIN 20 WHERE " _
        & "TargetInstance ISA 'CIM_DataFile' and " _
            & "TargetInstance.Name='" & strPnrPath01 & "'")


Do
    Set objLatestEvent = colMonitoredEvents.NextEvent
    'WScript.Echo "File: " & objLatestEvent.TargetInstance.Name
    'WScript.Echo "New size: " & objLatestEvent.TargetInstance.FileSize
    'Wscript.Echo "Old size: " & objLatestEvent.PreviousInstance.FileSize
    
    	Select Case objLatestEvent.Path_.Class
			'Case "__InstanceCreationEvent"
			'	WScript.Echo Now & vbTab & MyFile & " was created" & vbCrlf      
			'Case "__InstanceDeletionEvent"     
			'	WScript.Echo Now & vbTab & MyFile & " was deleted" & vbCrLf
			Case "__InstanceModificationEvent"
				If objLatestEvent.TargetInstance.LastModified <> objLatestEvent.PreviousInstance.LastModified Then
						'WScript.Echo Now & vbTab & MyFile & " was modified" & vbCrLf
						MsgBox "File was modified."
						
				End If
		End Select

    
Loop

Set objWMIService = Nothing
Set colMonitoredEvents = Nothing
Set objLatestEvent = Nothing

The text file is modified 5 or 6 times in a minute or two, and I would like to be notified only after the last file modification (the attached code notifies me after the first modification). How could I do that? (The text file modification procedure: the file is being changed many times - about 5 or 6 times - in a minute, after that minute the file is unchanged in the next several hours).

 

[Geates]

There really isn't a way to accurately msgbox you when the "last" modification has been done because the number of modifications to a file vary durings a varying amount of time.

Although, you could use a timing mechanism to emulate your request. Everytime a modification is encountered, set a var to now. At the end of the loop, check to see how long it's been since the last mod. If greater than x seconds, it may be safe to assume it was the last mod and the user should be notified.

...
Do
	Set objLatestEvent = colMonitoredEvents.NextEvent
	Select Case objLatestEvent.Path_.Class
		Case "__InstanceModificationEvent"
			If objLatestEvent.TargetInstance.LastModified <> objLatestEvent.PreviousInstance.LastModified Then
				dtmTimer = now
				blnNotify = true
			End If
	End Select

	if (blnNotify) then
		if (datediff("s", dtmTimer, now) > 30) then
			msgbox "The last file modification happened"
			blnNotify = false
		end if
	end if
Loop
...

-Geates

 

[strongm]

You might want to look at WQL's GROUP Clause

 

[Geates]

@Any: What is the benefit gained from using [tt]objWMIService.ExecNotificationQuery[/tt] over an FSO object?

-Geates

 

[strongm]

Mostly a dramatially lower CPU loading than when polling via FSO. There are a bunch of other advantages once you start wanting to monitor multiple files or folders, or group similar events together, or would like the notifications raised as events