Upload file to SharePoint Document library using powershell

I want to upload the same file to multiple site collections with the same hierarchy in all the site collections. I want to use PowerShell and include auto check-in/check-out functionality.

I have able to upload the file in SharePoint. Below is the code. :

[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint") > $null

# create the Variable Path and Pass the source folder path
$path = “D:\ABC\DEF\26Nov\”;

# create the Variable destination and pass the URL of the SharePoint List
$destination = "complete URL of File will be mentioned here";

# Store the current user default credentials in the Variable Credentials
$credentials = [System.Net.CredentialCache]::DefaultCredentials;

# Create the object of the Webclient
$webclient = New-Object System.Net.WebClient;

# Pass the user credentials
$webclient.Credentials = $credentials; Get-ChildItem

# “For Each” loop will upload all of the files one by one onto the destination using the UploadFile method
Get-ChildItem $path | ForEach-Object { $webclient.UploadFile($destination + “/” + $_.Name, “PUT”, $_.FullName)};

By this code the file is uploaded but checked out. I want it to be checked in automatically. In case the file is there then first automatically check-out and then check in.

Here is simple script in layman style which is tested and working fine to upload files from your drive to SharePoint document library

http://soreddymanjunath.blogspot.in/2014/07/add-file-to-document-library-using.html

cls
asnp "*sh*"
$url = Read-Host "Enter site URL" 
$web = Get-SPWeb -Identity $url

if ($web) {
   try {
      $list = $web.Lists.TryGetList("Documents")
      $files = Get-ChildItem -Path "D:\Manju" -Force -Recurse
      foreach ($file in $files) {
         $stream = $file.OpenRead()
         $done = $list.RootFolder.Files.Add($file.Name, $stream, $true)
         Write-Host $done.Name "Uploaded into the site" -BackgroundColor Green         
      }
   } catch {
      $ErrorMessage = $_.Exception.Message
      Write-Host $ErrorMessage
   }
} else {
   Write-Host "Site doesn't exist"
}

$list.Update();