For each thing in one CSV check for multiple types of matches in another CSV - powershell

Question

Sorry if the description is unclear, but I couldn't think of how else to word it.
I have two CSV files:
LocalAdmins.csv -- ColumnA = PC name; ColumnB = username in local admin group
Exempt.csv -- ColumnA = PC name; ColumnB = username allowed to be a local admin
What I'm trying to do is loop through LocalAdmins.csv, and for each one check to see if the PC name shows up in Exempt.csv (or matches any defined naming patterns in that file), and if a match is found, check to see if the local admin username for that PC in LocalAdmins.csv shows up in the list of AllowedUsers for that PC in Exempt.csv.
If the username is NOT in the AllowedUsers list, or if the PC name is not in Exempt.csv, then output the entry from LocalAdmins.csv. Here is what I have so far:
$admins = Import-Csv .\LocalAdmins.csv
$exempt = Import-Csv .\Exempt.csv
$violations = ".\Violations.csv"
foreach ($admin in $admins) {
foreach ($item in $exempt) {
if ($admin.PC -like $item.PC) {
if ($admin.Name -notin ($item.AllowedUsers -split ",")) {
$admin | Export-Csv $violations -Append -NoTypeInformation
}
}
else {
$admin | Export-Csv $violations -Append -NoTypeInformation
}
}
}
The problem is the nested foreach loop generates duplicates, meaning if there are 3 lines in Exempt.csv then a single entry in LocalAdmins.csv will have 3 duplicate outputs (one for each line in Exempt.csv). So the output looks like this:
When it should look like this:
I'm guessing the problem is somewhere in the structure of the loops, but I just need some help figuring out what to tweak. Any input is greatly appreciated!

Answer 1

Not optimized (unique sort by any property should work):
$admins = Import-Csv .\LocalAdmins.csv
$exempt = Import-Csv .\Exempt.csv
$violations = ".\Violations.csv"
$(
foreach ($admin in $admins) {
foreach ($item in $exempt) {
if ($admin.PC -like $item.PC) {
if ($admin.Name -notin ($item.AllowedUsers -split ",")) {
$admin
}
}
else {
$admin
}
}
}
) | Sort-Object -Property PC, Name -Unique |
Export-Csv $violations -Append -NoTypeInformation

Answer 2

With better restrictions of the forEach, there shouldn't be duplicates
and no need to Sort -unique.
Getting input from here-strings
## Q:\Test\2019\02\05\SO_54523868.ps1
$admins = #'
PC,NAME
XYZlaptop,user6
workstationXYZ,user7
computerABC,user8
ABClaptop,user1
'# | ConvertFrom-Csv # .\LocalAdmins.csv
$exempt = #'
PC,AllowedUsers
*laptop,"user1,user2"
computerXYZ,"user3,user4"
workstation*,"user5"
'# | ConvertFrom-Csv # .\Exempt.csv
$violationsFile = ".\Violations.csv"
$violations = foreach ($admin in $admins) {
$violation = $True
foreach ($item in ($exempt|Where-Object {$admin.PC -like $_.PC})){
if ($admin.NAME -in ($item.AllowedUsers -split ',')){
$violation = $False
}
}
if ($violation){$admin}
}
$violations
$violations | Export-Csv $violationsFile -NotypeInformation
## with Doug Finke's ImportExcel module installed, you can directly get the excel file:
#$violations | Export-Excel .\Violatons.xlsx -AutoSize -Show