Add an attachment to the SharePoint 2010 list item using web service in powershell

Steps Involved:

1. Open SharePoint 2010 Management Shell by going to Start | All Programs | SharePoint | Microsoft SharePoint 2010 Products | SharePoint 2010 Management Shell (Run as Administrator).
2. Run the following script.

Powershell Script:

## Input Parameters required for attaching a file to the list item       $uri="http://serverName:10736/sites/ECT/_vti_bin/Lists.asmx?wsdl"       [string] $listItemId="3"       [string] $listName="List"       [string] $fPath = "D:\Lists.xml"                ## Check if the file exists in the path specified       if([System.IO.File]::Exists($fPath))       {             ## Read the file             $fStream=[System.IO.File]::OpenRead($fPath)             [String] $fName=$fStream.Name             [System.Byte[]]$bytes=New-Object -TypeName System.Byte[] -ArgumentList $fStream.Length             $fStream.Read($bytes, 0, [int]$fStream.Length)           $fStream.Close()                         ## Attach the file to the list item using web service             $listWebServiceReference = New-WebServiceProxy -Uri $uri -UseDefaultCredential             Write-Host -ForegroundColor Magenta "Adding the attachement to the list item........."             $listWebServiceReference.AddAttachment($listName,$listItemId,$fName,$bytes)             Write-Host -ForegroundColor Green $fName " is attached successfully to the list item"             }       else       {           Write-Host -ForegroundColor Yellow "File does not exists in the specified path " $fPath       }

For more information on New-WebServiceProxy please refer http://technet.microsoft.com/en-us/library/dd315258.aspx.