Powershell FileSystemWatcher script firing twice on some new files

Question

I'm using FileSystemWatcher to monitor a folder where documents are scanned to. When a new file is detected, it will send an email to notify someone. It's working as is, but sometimes (not every file) it will trigger 2 or 3 times on a new file and send the email 2-3 times for the same file. I'm guessing it has to do with the way the file is created by the scanner or something like that.

I'm trying to figure out a way to protect against this happening, to ensure it only sends one email per file. Any suggestions would be greatly appreciated.

$PathToMonitor = "\\path\to\folder"

$FileSystemWatcher = New-Object System.IO.FileSystemWatcher
$FileSystemWatcher.Path  = $PathToMonitor
$FileSystemWatcher.Filter  = "*.*"
$FileSystemWatcher.IncludeSubdirectories = $false

$FileSystemWatcher.EnableRaisingEvents = $true

$Action = {
    if ($EventArgs.Name -notlike "*.pdf" -and $EventArgs.Name -notlike "*.tif") {
        return
    }
        $details = $event.SourceEventArgs
        $Name = $details.Name
        $Timestamp = $event.TimeGenerated
        $text = "{0} was submitted on {1}." -f $Name, $Timestamp
        
        $FromAddress = "Email1 <email1@email.com>"
        $ToAddress = "Email2 <Email2@email.com>"
        $Subject = "New File"
        $SMTPserver = "123.4.5.678"
    
        Send-MailMessage -From $FromAddress -To $ToAddress -Subject $Subject -Body $text -SmtpServer $SMTPserver
    
}

$handlers = . {
    Register-ObjectEvent -InputObject $FileSystemWatcher -EventName Created -Action $Action -SourceIdentifier FSCreateConsumer
}

try {
    do {
        Wait-Event -Timeout 5
    } while ($true)
}
finally {
    Unregister-Event -SourceIdentifier FSCreateConsumer
    
    $handlers | Remove-Job
    
    $FileSystemWatcher.EnableRaisingEvents = $false
    $FileSystemWatcher.Dispose()
}

Answer 1

This may be because you listen too many notifications . The default is LastWrite , FileName , and DirectoryName FileName is sufficient for your need and may prevent your issue.

$FileSystemWatcher.NotifyFilter = [System.IO.NotifyFilters]::FileName

As a remark, I don't know why you use Wait-Event -Timeout 5 . Script is working fine without the try{} block.

Answer 2

I had to adjust these two things to make it work:

if ($MonitoredFiles.TryAdd($Event.SourceEventArgs.Name, $Event.TimeGenerated))

if ($OriginEventDate -ne [System.DateTime]::MinValue -and $OriginEventDate.AddMinutes($KeepFiles) -ge $Now)