Finding modified date of a file/folder

If you run the Get-Item or Get-ChildItem commands these will output System.IO.FileInfo and System.IO.DirectoryInfo objects that contain this information e.g.:

Get-Item c:\folder | Format-List  

Or you can access the property directly like so:

Get-Item c:\folder | Foreach {$_.LastWriteTime}

To start to filter folders & files based on last write time you can do this:

Get-ChildItem c:\folder | Where{$_.LastWriteTime -gt (Get-Date).AddDays(-7)}

To get the modified date on a single file try:

$lastModifiedDate = (Get-Item "C:\foo.tmp").LastWriteTime

To compare with another:

$dateA= $lastModifiedDate 
$dateB= (Get-Item "C:\other.tmp").LastWriteTime

if ($dateA -ge $dateB) {
  Write-Host("C:\foo.tmp was modified at the same time or after C:\other.tmp")
} else {
  Write-Host("C:\foo.tmp was modified before C:\other.tmp")
}