Find the oldest file in each subdirectory with Powershell - powershell

Question

My company recently moved to outlook365. We are entirely VDI based so our user profiles are stored on a single server. As a result our users all now have 2+ .ost files taking up storage space on the server. I'd like to write a script to find and delete the extraneous .ost files. In addition I'd like to schedule the script to run on a monthly basis to clean up any orphaned .ost's that occur for any other reason.
I've tried a few different solutions but can't seem to find the right syntax to identify just the oldest/original .ost in each subdirectory, all attempts have identified the oldest file from the whole directory or all .ost files in the directory.
$Path = "<path>"
$SubFolders = dir $Path -Recurse | Where-Object {$_.PSIsContainer} | ForEach-Object -Process {$_.FullName}
ForEach ($Folder in $SubFolders)
{
$FullFileName = dir $Folder | Where-Object {!$_.PSIsContainer} | Sort-Object {$_.LastWriteTime} -Descending | Select-Object -First 1
}

Answer 1

Inside of your loop, you could use the following to list the .ost file that has the oldest LastWriteTime value. Just add the -Descending flag to Sort-Object to list the newest file.
$FullFileName = foreach ($folder in $Subfolders) {
$Get-ChildItem -Path $folder -Recurse -File -Filter "*.ost" |
Sort-Object -Property LastWriteTime |
Select-Object -Property FullName -First 1
}
$FullFileName
If there is only one .ost file found in the $folder path, it will still find that file. So you will need logic to not delete when there is only one file. This does not guarantee it is the oldest file. You probably want a combination of the oldest CreationTime and newest LastWriteTime. The following will list the oldest .ost file based on CreationTime.
$FullFileName = foreach ($folder in $Subfolders) {
Get-ChildItem -Path $folder -Recurse -File -Filter "*.ost" |
Sort-Object -Property CreationTime |
Select-Object -Property FullName -First 1
}
$FullFileName
Another issue is setting the $FullFileName variable inside of the foreach loop. This means it will be overwritten through each loop iteration. Therefore, if you retrieve the value after the loop completes, it will only have the last value found. Setting the variable to be the result of the foreach loop output will create an array with multiple values.
To only output an OST file path when there are multiple OST files, you can do something like the following:
$FullFileName = foreach ($folder in $Subfolders) {
$files = Get-ChildItem -Path $folder -Recurse -File -Filter "*.ost" |
Sort-Object -Property LastWriteTime -Descending
if ($files.count -ge 2) {
$files | Select-Object -Property FullName -First 1
}
$FullFileName

Answer 2

This one liner should do the job, keeping the ost file with the newest LastWriteTime
gci -Path $Path -directory | where {(gci -Path $_\*.ost).count -gt 1}|%{gci -Path $_\*.cmd|Sort-Object LastWriteTime -Descending|Select-Object -Skip 1|Remove-Item -WhatIf}
Longer variant follows.
$Path = '<path>'
$Ext = '*.ost'
Get-ChildItem -Path $Path -directory -Recurse |
Where-Object {(Get-ChildItem -Path "$_\$Ext" -File -EA 0).Count -gt 1} |
ForEach-Object {
Get-ChildItem -Path "$_\$Ext" -File -EA 0| Sort-Object LastWriteTime -Descending |
Select-Object -Skip 1 | Remove-Item -WhatIf
}
The first two lines evaluate folders with more than one .ost file
The next lines iterates those folders and sort them descending by LastWriteTime, skips the first (newest) and pipes the other to Remove-Item with the -WhatIf parameter to only show what would be deleted while testing.
You can of course also move them to a backup location instead.