Powershell Script to Edit a List Item and Set the Value for Field

The powershell script does the following functionalities, 

1. Loops through all the lists in the given site collection.
   
   
2. Filters the list based on document library.
   
   
3. Finds the specific/given list given in the script.
   
   
4. Loops through all the items in the given list.
   
   
5. Searches for a current value in one of the column for the list.
   
   
6. It replaces/sets the value for the column with the given new value only if it satisfies the given criteria. 

#Loops through each items in the given list and locates the column name "ColumnName" and checks whether the value for that field is "Test", if so it replaces it with #"Test1" and updates the item and updates the list.

$LogTime = Get-Date -Format yyyy-MM-dd_hh-mm
$LogFile = ".\EditListItemPatch-$LogTime.rtf"

# Add SharePoint PowerShell Snapin


if ( (Get-PSSnapin -Name Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue) -eq $null ) {
    Add-PSSnapin Microsoft.SharePoint.Powershell
}

$scriptBase = split-path $SCRIPT:MyInvocation.MyCommand.Path -parent
Set-Location $scriptBase


#Deleting any .rtf files in the scriptbase location
$FindRTFFile = Get-ChildItem $scriptBase\*.* -include *.rtf
if($FindRTFFile)
{
 foreach($file in $FindRTFFile)
  {
   remove-item $file
  }
}


start-transcript $logfile

$siteURL = read-host "Enter the site collection URL "
$sitecollection = get-spsite $siteURL
foreach($web in $sitecollection.allwebs)
{
 write-host $web.url -fore yellow
 $lists = $web.lists
 foreach ($list1 in @($lists))
 {
  if ($list1.BaseType -eq [Microsoft.SharePoint.SPBaseType]::DocumentLibrary)
  {
   $list = $web.Lists[$list1.title]


   if($list.title -eq "TestList")
   {
    write-host $list.title -fore green
    $items = $List.items

    foreach($item in @($items))
    {
     ##########Put in your logic here###########################
     $value = $item["ColumnName"]
     write-host $value

     if($value -eq "Test")
     {
      $NewValue = "Test1"
      $item["ColumnName"] = $NewValue

     }
     ##########Put in your logic here###########################
     $item.update()
    }
    $list.update()
   }
  }
 }
}

stop-transcript