Scripting a URL validity check from a text file list - url

Question

I am trying to modify the PowerShell script I have found on ElegantCode.Com. I want to change it to specify a large text file of HTTP links, rather than naming the links as a parameter individually.
Once the script parses the file, I want it to pipe or echo out only the links that are valid back to a new file.
I am falling at the first hurdle and can't even figure out how I pass the input file in as a parameter.
Direct link for the script is here
BEGIN {
}
PROCESS {
$url = $_;
$urlIsValid = $false
try
{
$request = [System.Net.WebRequest]::Create($url)
$request.Method = 'HEAD'
$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 {
}

Answer 1

It appears the script it expecting the url to be piped in. The variable $_ represents the current pipeline object. So if the text file contained on URL per line you could do something like this:
Get-Content Urls.txt | Where {$_ -notmatch '^\s*$'} | Check-Url
I put the where in the pipe to eliminate blank lines.

Answer 2

To pipe the valid urls to a file as requested (adding to Keith's answer):
$validUrls = ".\ValidUrls.txt"
if (Test-Path $validUrls) { Remove-Item -Force $validUrls }
$result = New-Item -Type File -Path $validUrls
Get-Content Urls.txt | Where {$_ -notmatch '^\s*$'} | Foreach-Object {
$url = ($_ | Check-Url)
if ($url.IsValid)
{
$url.Url | Out-File $result -Append
}
}