Enable text preview pane for a given extension in Windows Explorer.

AddExtensionToWindowsExplorerPreview.ps1

#############################################################################
# This script will enable preview for a given extension in Windows Explorer.
# Based on original by Bhargav Shukla http://www.bhargavs.com
# 
# DISCLAIMER
# ==========
# THIS CODE IS MADE AVAILABLE AS IS, WITHOUT WARRANTY OF ANY KIND. THE ENTIRE 
# RISK OF THE USE OR THE RESULTS FROM THE USE OF THIS CODE REMAINS WITH THE USER.
#############################################################################
param (
  [Parameter(Mandatory = $true)]
  [string]$extension = "ps1"
)

# Check if OS is Windows 7 or Windows Server 2008 R2, quit if not.
$OS = (Get-WmiObject -Class win32_OperatingSystem).caption
echo $OS
switch -wildcard ($OS) {
  "*Windows 7*" { "`nChecking Elevation..." }
  "*Windows 10*" { "`nChecking Elevation..." }
  "*Windows Server 2008 R2*" { "`nChecking Elevation..." }
  default { Write-Host -ForegroundColor Red "`nYou are not running Windows 7 or Windows Server 2008 R2. You can't use this feature on older OS."; exit }
}

# Function to check if PowerShell is running elevated
function Check-Elevated {
  $wid = [System.Security.Principal.WindowsIdentity]::GetCurrent()
  $prp = new-object System.Security.Principal.WindowsPrincipal($wid)
  $adm = [System.Security.Principal.WindowsBuiltInRole]::Administrator
  $IsAdmin = $prp.IsInRole($adm)
  if ($IsAdmin) {
    Set-Variable -Name elevated -Value $true -Scope 1
  }
}

# Make registry changes if running elevated, throw error if not
Check-Elevated
If ($elevated -eq $true) {
  # Set Registry Key variables
  $REG_KEY = ".$extension"
         
  # Open remote registry (The local machine registry is opened if machineName is String.Empty.)
  $reg = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('ClassesRoot', "")
   
  # Open the targeted remote registry key/subkey as read/write
  $regKey = $reg.OpenSubKey($REG_KEY, $true)
       
  # Set PerceivedType to "text"
  if ($regKey -ne $null) {
    $regKey.Setvalue('PerceivedType', 'text', 'String')
    $regKey.Setvalue('Content Type', 'text/plain', 'String')
        
    # Close the Reg Key
    $regKey.Close()
 
    Write-Host -ForegroundColor Green -BackgroundColor Black "Preview for $REG_KEY files is now enabled. Enable preview pane in Windows Explorer.`n"
          
  }

}
else {
  Write-Host -ForegroundColor Red -BackgroundColor Black "Please run PowerShell as administrator before you run this script.`n"
}