Check if files exist using PowerShell

The file controls.txt contains a list of filenames with path.
We want to find non existent files

cat .\controls.txt | Where-Object {-not (test-path $_)}

Get unique sorted lines from file and save to another file.

cat .\controls.txt | Sort-Object | Get-Unique > .\controls-sorted.txt

Url checker with powershell

<#
.SYNOPSIS
Takes a list of urls and verifies that the url is valid.
.DESCRIPTION
The Check-Url script takes a piped list of url and attempts download the HEAD of the file from the web. If it retrieves an HTTP status of OK then the URL is reported as valid. If the result is anything else or an exception, then the url is reported as invalid.
.INPUTS
List of url's to check. Note: the url's must begin with http:// or https://
.OUTPUTS
Returns a powershell object with properties
 1. IsValid [bool] - signifies weather the url was determined as Valid or not
 2. Url [string] - the url that was checked.
 3. HttpStatus - The http status resulting from the web request.
 4. Error - Any possible error resulting from the request.
.EXAMPLE
@('http://www.google.com', 'http://www.asd----fDSAWQSDF-GZz.com') | .\Check-Url.ps1
.EXAMPLE
@('http://www.google.com', 'http://www.asd----fDSAWQSDF-GZz.com') | .\Check-Url.ps1 | where { !$_.IsValid }
Reports the Invalid url's.
#>
 BEGIN {
}
PROCESS {
  ## You have to at least make sure it's got a value
  ## Really you should check it's TYPE to make sure you can do something useful...
  if($_) {

 $url = $_;
 $urlIsValid = $false
 try
 {
  $request = [System.Net.WebRequest]::Create($url)
  $request.Method = 'HEAD'
        $request.AllowAutoRedirect=$false
        $request.Timeout = 5000
        $request.AuthenticationLevel = "None"
  $response = $request.GetResponse()
  $httpStatus = $response.StatusCode
  $urlIsValid = ($httpStatus -eq 'OK')
  $tryError = $null
  $response.Close()
 }
 catch [System.Exception] {
  $httpStatus = $null
  $tryError = $_.Exception
  $urlIsValid = $false;
 }
 $x = new-object Object | `
   add-member -membertype NoteProperty -name IsValid -Value $urlIsvalid -PassThru | `
   add-member -membertype NoteProperty -name Url -Value $_ -PassThru | `
   add-member -membertype NoteProperty -name HttpStatus -Value $httpStatus -PassThru | `
   add-member -membertype NoteProperty -name Error -Value $tryError -PassThru
 $x
  }
}
END {
}
<#
 References...

 http://stackoverflow.com/questions/924679/c-how-can-i-check-if-a-url-exists-is-valid
 http://huddledmasses.org/using-script-functions-in-the-powershell-pipeline/
#>
 

How to run from powershell console
gc .\urls.txt |  .\urlcheck3.ps1