Powershell: Get-ChildItem, get latest file of files with similar names - powershell

Question

I got a script to get files from a folder that I then put in a HTML-Table and mail.
In the folder you have files like HR May 2020, HR April 2020, RR May 2021 etc.
Below is the code itself as a sample, this looks for other files but they come every month as well. In total I will filter 8 files.
Get-ChildItem -Path D:\Temp\Test |
Where-Object { $_.Name -match '^RR_Prognos.*|^AllokeringBogNycklar.*' } |
Sort-Object -Property LastWriteTime |
Select-Object LastWriteTime,FullName
Now I am only interested in seeing the latest file of each, so using last or -days, month, hours or similar wont work.
I tried to find a better solution googling it but could not come up with anything that solved the problem.
So I just need to add to the code it it picks the lastest of each file i filter on, the filter is so it does not care about the month in the name.
Edit: Lets say I would use:
Get-ChildItem -Path c:\tm1 | Where-Object { $_.Name -match '^RR_Prognos.*|^AllokeringBogNycklar.*|^Aktivversion.*|^AllokeringNycklar.*|^HR_prognos.*|^KostnaderDK.*|KostnaderProdukt_prognos.*|^Parametrar_prognos.*|ProduktNyckel_prognos apr.*' } | Sort-Object -Property LastWriteTime -Descending | Select-First 8 | Select-Object LastWriteTime,FullName
Then if one file does not come with the batch, it would show the 2nd last one of that as well. Is there a easier way to block that from happening?

Answer 1

Ok, now that you've provided the whole list that you filter against I can write up a real answer. Here we'll group by file name, then sort each group and grab the last one from each group:
Get-ChildItem -Path c:\tm1 |
Where-Object { $_.Name -match '^RR_Prognos.*|^AllokeringBogNycklar.*|^Aktivversion.*|^AllokeringNycklar.*|^HR_prognos.*|^KostnaderDK.*|KostnaderProdukt_prognos.*|^Parametrar_prognos.*|ProduktNyckel_prognos apr.*' } |
Group {$_.Name -replace '.*?(^RR_Prognos|^AllokeringBogNycklar|^Aktivversion|^AllokeringNycklar|^HR_prognos|^KostnaderDK|KostnaderProdukt_prognos|^Parametrar_prognos|ProduktNyckel_prognos apr).*','$1'} |
ForEach-Object {
$_.Group |
Sort-Object -Property LastWriteTime -Descending |
Select -First 1
} |
Select-Object LastWriteTime,FullName

Answer 2

This might be what you are looking for. This iterates over each search string where you need the newest file.
$searchStrings = #('^pattern1*', '^pattern2*', '^pattern3*')
foreach($searchString in $searchStrings) {
$items = Get-ChildItem -Path $folder | Where-Object { $_.Name -match "$searchString" } | Sort-Object -Property LastWriteTime -Descending
$newestItem = $items[0]
Write-Host "newest item for '$searchString' is $newestItem"
}