Finding the item from csv1 that is not in csv2 and exporting it-CodePudding

I am trying to use powershell to find the users that has been newly added to an Active directory group. I export the membership of the groups daily into a csv and is now trying to get the newly added group members by comparing the previous day's and the current day's csv file.

Here is the function I use to check if the a user from the current day's csv does not exist on the previous day's csv (which means that they are newly added).

$file1 = Import-Csv -path "C:\test\members_previous.csv" 
$file2 = Import-Csv -path "C:\test\members_Current.csv" 

foreach ($Item in $file2.samaccountname)
{
    if ($Item -in $file1.samaccountname)
    {
        $true
    }
    else
    {
        $item
    }
  
}

export-csv -path "C:\test|result.csv" -NoTypeInformation

The csv file from the export does not contain anything inside.

I'm not sure how I can export only the results of the else statement into a csv. The "$item" value in the else statement contains the samaccountname of the user.

I think the solution might be simple, but I can't figure it out.

Thank you in advance for any suggestion!

CodePudding user response：

I will assume there is something missing in your question's code, Export-Csv will require an "Input Object" to perform any operation and currently there is none.

What you're looking to do can be simplified using Where-Object to filter all objects where the samaccountname values are not present in the reference CSV (previous day):

$ref = Import-Csv "C:\test\members_previous.csv" 

Import-Csv "C:\test\members_Current.csv" |
    Where-Object { $_.samaccountname -notin $ref.samaccountname } |
        Export-Csv C:\test\result.csv -NoTypeInformation

If both CSVs are really big, then you might want to change the code a bit so it's more efficient:

$ref = Import-Csv "C:\test\members_previous.csv" |
    Group-Object samaccountname -NoElement -AsHashTable -AsString

Import-Csv "C:\test\members_Current.csv" |
    Where-Object { -not $ref.ContainsKey($_.samaccountname) } |
        Export-Csv C:\test\result.csv -NoTypeInformation

CodePudding user response：

A little improvement on @santiagosquarzon answer.

# Create output file
$outFile = "c:\test\report.csv"

$outData = New-Object -TypeName System.Text.StringBuilder
[void]$outData.AppendLine("samAccountName,Status")

# Create the dictionary based on the previous members results
$content = Import-CSV -Path c:\test\members_previous.csv
$lookup = $content | Group-Object -AsHashTable -AsString -Property samAccountName

$count = 0

# Start cycling through the master list
Import-Csv -Path c:\test\members_current.csv | foreach {
    $samAccountname = $PSItem.samaccountname
    $found = $lookup[$samAccountname]
    if ($found)
    {
        $status = "Match"
    }
    else
    {
        $status = "No Match"
        $count  
    }
    [void]$outData.AppendLine("`"$samAccountName`",`"$status`"")
}

# Write the output to a file
$outData.ToString() | Out-File -FilePath $outFile -Encoding ascii
Write-Host "Found $count unmatched systems" -ForegroundColor Yellow