Powershell, Directory Verification - arrays

Question

I am fairly new to PowerShell. I have created an exe that can be ran by a coworker that will go to 8 separate sql servers, to individual directories and check them for a list of created files. My current code checks for age less than one day and that it's not empty, however, I have been presented with a new problem. I need to be able to take a list in a text file/array/csv/etc and compare the list to the directory to ensure that there are not any additional files in the folder. All of the information is then formatted, exported to a file, and then emailed to certain recipients.
My question is, how do I create a script that works using this idea; preferably without considerable change to my current code as it is fairly length considering the sub directories of the 8 sql servers.. (current script redacted is as follows):
$today = get-date
$yesterday = $today.AddDays(-1)
$file_array = "XXX_backup*.trn", "XXX_backup*.bak", "XXY_backup*.trn", "XXY_backup*.bak"
$server_loc = \\hostname\e$\
$server_files = #(get-childitem $server_loc | where-object {$_.fullname -notmatch "(subdirectory)})
$server_complete_array = #("Files Directory ($server_loc)", " ")
foreach ($file in $files) {
IF ($file.length -eq 0) {
[string]$string = $file
$server_complete_Array = $server_complete_Array + "$string is empty."
}
elseif ($file.LastWriteTime -lt $yesterday) {
[string]$string = $file
$server_complete_Array = $server_complete_Array + "$string is old."
}
else {
[string]$string = $file
$server_complete_Array = $server_complete_Array + "$string is okay."}
}
Thank you for your help in advance. :)

Answer 1

Bit of a hack, but it should work with what you already have:
$file_array = "XXX_backup*.trn", "XXX_backup*.bak", "XXY_backup*.trn", "XXY_backup*.bak"
$FileNames = $server_files | select -ExpandProperty Name
$FileCheck = ('$Filenames ' + ($file_array | foreach {"-notlike '$_'"}) -join ' ')
Since you're already using wildcards in your file specs, this works with that by creating a command which filters the file name array through a series of -notlike operators, one for each file spec.
$FileCheck
$Filenames -notlike 'XXX_backup*.trn' -notlike 'XXX_backup*.bak' -notlike 'XXY_backup*.trn' -notlike 'XXY_backup*.bak'
Each one will filter out the names that match the file spec and pass the rest onto the next -notlike operator. Whatever falls out the end didn't match any of them
At this point $FileCheck is just a string, and you'll need to use Invoke-Expression to run it.
$ExtraFiles = Invoke-Expression $FileCheck
and then $ExtraFiles should contain the names of all the files that did not match any of the file specs in $file_array. Since the filters are being created from $file_array, there's no other maintenance to do if you add or remove filespecs from the array.