Sometimes you might want to abort a pipeline when a certain condition is met.
Here is a creative way of doing this. It works all the way back to PowerShell 2.0.
Take a look at the sample code:
filter Stop-Pipeline { param ( [scriptblock] $condition = {$true} ) if (& $condition) { continue } $_ } do { Get-ChildItem c:\Windows -Recurse -ErrorAction SilentlyContinue | Stop-Pipeline { ($_.FullName.ToCharArray() -eq '\').Count -gt 3 } } while ($false)
The pipeline recursively scans the Windows folder. There is a new command called Stop-Pipeline. You can assign it a script block, and if this script block evaluates to $true, the pipeline is aborted.
In this example, you control the recursion depth. Once there are more than three backslashes in a path, the pipeline stops. Increase the number "3" to a higher number in order to recurse deeper into a folder.
The trick requires the pipeline to be embedded in a "do" loop because Stop-Pipeline basically just calls "Continue" when the condition is met, making the do loop abort what it was doing (executing the pipeline).
This sounds awkward but works beautifully. Here is a slight adaption. It will run the pipeline for a maximum of 10 seconds:
$start = Get-Date $MaxSeconds = 10 do { Get-ChildItem c:\Windows -Recurse -ErrorAction SilentlyContinue | Stop-Pipeline { ((Get-Date) - $start).TotalSeconds -gt $MaxSeconds } } while ($false)
Simply place a variable before the "do" statement if you want to save the pipeline results rather than outputting them.
$result = do { Get-Chil...
