Exclude negative integers in result - object

Question

I am trying to check for expired certs. The problem is we leave expired ones on our servers sometimes for reference, and I only want to display ones leading up to an expiration. How do I exclude negative integers in this case?
Example output:
Expires In (Days) : -25 NotAfter : 9/1/2018 10:56:27 AM Subject : CN=SERVER01.domain.com Issuer : CN=SOMEAUTHICA01, DC=domain, DC=com
Expires In (Days) : -17 NotAfter : 9/9/2018 3:45:55 PM Subject : CN=SERVER02.domain.com Issuer : CN=SOMEAUTHICA01, DC=domain, DC=com
$threshold = 30 #Number of days to look for expiring certificates
$deadline = (Get-Date).AddDays($threshold) #Set expiration deadline date
$serverList = 'SERVER01.domain.com','SERVER02.domain.com'
$expired = Invoke-Command -ComputerName $serverList { Dir Cert:\LocalMachine\My } | Sort-Object -Property NotAfter | Get-Unique | foreach {
If ($_.NotAfter -le $deadline) {$_ | Select Issuer, Subject, NotAfter, #{Label="Expires In (Days)";Expression={($_.NotAfter - (Get-Date)).Days}} }
}

Answer 1

You have to exclude the certificates that are already expired. This can be done as follows.
$threshold = 30; #Number of days to look for expiring certificates
$deadline = (Get-Date).AddDays($threshold); #Set expiration deadline date
$serverList = 'SERVER01.domain.com','SERVER02.domain.com';
$expired = Invoke-Command -ComputerName $serverList { Dir Cert:\LocalMachine\My } | Sort-Object -Property NotAfter | Get-Unique | foreach {
If ($_.NotAfter -le $deadline -and $_.NotAfter -gt (Get-Date).Days) {$_ | Select Issuer, Subject, NotAfter, #{Label="Expires In (Days)";Expression={($_.NotAfter - (Get-Date)).Days}} }
}