Post-order Traverse in PowerShell recurse - powershell

Question

Get-ChildItem -Recurse in powershell currently traverse a directory in level order fashion. Is there any way to traverse a directory in post-order way in Powershell?
I am trying to delete files which are older than certain times. and after deleting files, if subfolder is empty, delete that folder too. Right now am doing this.
$path = 'D:\Files'
Get-ChildItem -Path $path -Recurse | Where-Object {
(($_.LastWriteTime -lt (Get-Date).AddDays(-30)) -and ($_ -is [system.io.fileinfo]) )
} | Remove-Item
Get-ChildItem -Path $path -Recurse | Where-Object {
($_ -is [System.IO.DirectoryInfo]) -and $_.CreationTime -lt (Get-Date).AddDays(-30) -and ((Get-ChildItem $_.FullName).Count -eq 0)
} | Remove-Item -Force
But I want to do it in a single command. Not as two different command.

Answer 1

You could reverse the order of the items returned by Get-ChildItem with [Array]::Reverse
Full script:
$items = Get-ChildItem 'D:\Files' -Recurse
[Array]::Reverse($items)
$date = (Get-Date).AddDays(-30)
foreach ($item in $items) {
if ($item.PSIsContainer) {
if ($item.CreationTime -lt $date -and (Get-ChildItem $item.FullName).Count -eq 0) {
Remove-Item $item.FullName
}
}
elseif ($item.LastWriteTime -lt $date) {
Remove-Item $item.FullName
}
}

Answer 2

I couldn't get the post order working properly with GCI, someone claimed it should, but it wasn't traversing depth first. Below is a naive implementation of the classic post order algorithm using the push directory and pop directory commands. Put your "actions" where Write-Host is.
function PostOrder($d){
pushd $d
$folders = Get-ChildItem .\ -Directory -Force
foreach ($folder in $folders){
PostOrder($folder)
}
popd
Write-Host $d.FullName
}
PostOrder("C:\myFolder")