Powershell Remove Oldest Items - loops

Question

I am trying to use a do while loop to remove old files in multiple directories (starting from the oldest) until there is one left, at which point the program should end. The program should also only run if there is more than one file in the directory at runtime.
Here is my environment:
Top Folder
Folder 1
Folder 2
etc
In Folder 1, Folder 2, etc there should only be one file. The script should delete everything but the latest and nothing at all if there is only one file in there to begin with.
I have semi-accomplished this using the following code:
$basedir = "C:\Test"
Set-Location -Path C:\Test
$a = Get-ChildItem -recurse $basedir
if ($a.Count -gt 1) {
do
{
$a | Sort-Object LastWriteTime -Descending | Select-Object -Last 1 | remove-item
}
while
(
$a.Count -gt 1
)
}
It will only run when there is more than one file present, which is correct.
It correctly deletes the oldest file, but then it keeps on trying to delete the same file rather than rechecking the directory.
All I need help with at this point is getting it to re-run the loop once it has deleted a file, rather than trying to delete the same file over and over.
Thank you, sincerely, for any help and I apologise if this has been answered before. I did a lot of searching but couldn't find something with my situation.
Brad

Answer 1

To fix yours, you should re-define $a every time you pass through the loop, or just avoid using $a altogether. $a doesn't change just because the child items that were there when you created the object have.
Another way to do it would be to just select the last n-1 items in the folder.
#Get Items that aren't folders
$items = Get-ChildItems "c:\test" | ? {!($_.PSIsContainer)}
#Get a count - this is easier in PoSh 3
$itemCount = ($items | Measure-Object).Count
if ($itemCount -gt 1){
$items | Sort-Object LastWriteTime -Descending | Select-Object -Last ($itemCount - 1) | Remove-Item
}
To do this recursively is also fairly easy. First we get all of the folders we'll need to do the work in, then we'll move the code above into a foreach loop:
$folders = Get-ChildItems "C:\test" -recurse | ? {$_.PSIsContainer}
foreach ($folder in $folders) {
#Get Items that aren't folders
$items = Get-ChildItems $folder.FullName | ? {!($_.PSIsContainer)}
#Get a count - this is easier in PoSh 3
$itemCount = ($items | Measure-Object).Count
if ($itemCount -gt 1){
$items | Sort-Object LastWriteTime -Descending | Select-Object -Last ($itemCount - 1) | Remove-Item
}
}
You might need to run both scripts to prune the root as well, or add something like $folders += Get-Item "C:\test" before the foreach loop