Powershell script to update a field value (recursively) in sharepoint form a .CSV file and not changing the updated by value

Question

need to run through a list of old to new data (.csv) file and change them in a sharepoint list - can not make it work
here is my base attempt.
$web = Get-SPWeb site url
$list = $web.lists["List Name"]
$item = $list.items.getitembyid(select from the items.csv old)
$modifiedBy = $item["Editor"]
#Editor is the internal name of the Modified By column
$item["old"] = "new from the .csv file parsed by power sehll
$ite.Syste,Update($false);
$web.Dispose()

Answer 1

Hi,
According to your description, my understanding is that  you want to update SharePoint field value from a CSV file recursively.
We can import CSV file using the Import-CSV –path command, then update the field value in the foreach loop.
Here is a code snippet for your reference:
Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue
$csvVariable= Import-CSV -path "http://sp2010.contoso.com/finance/"
# Destination site collection
$WebURL = "http://sp2010.contoso.com/sites/Utility/"
# Destination list name
$listName = "Inventory"
#Get the SPWeb object and save it to a variable
$web = Get-SPWeb -identity $WebURL
#Get the SPList object to retrieve the list
$list = $web.Lists[$listName]
#Get all items in this list and save them to a variable
$items = $list.items
#loop through csv file
foreach($row in $csvVariable)
#loop through SharePoint list
foreach($item in $items)
$item["ID #"]=$row."ID #"
$item.Update()
$web.Dispose()
Here are some detailed articles for your reference:
http://blogs.technet.com/b/stuffstevesays/archive/2013/06/07/populating-a-sharepoint-list-using-powershell.aspx
http://social.technet.microsoft.com/wiki/contents/articles/25125.sharepoint-2013-powershell-to-copy-or-update-list-items-across-sharepoint-sites-and-farms.aspx
Thanks
Best Regards
Jerry Guo
TechNet Community Support