Comparing 2 CSV files in powershell exporting difference to another file.

Question

I've write this script out, and could have swore I had it giving me a Failed early this morning but now I'm getting nothing and not sure why.

Basically I need to compare $SourceAddress with $OutputAddress and export what is the difference between the files to another CSV. Any help on how to get the output file would be appreciated. Or a better way to do the comparison other than the 'Compare-Object' cmdlet would be awesome. Thanks.

###########################################################
#
# Douglas Francis
# DNS Audit Script
# V 1.2
# Date: 05/06/2014
#
# Pulls IP address from a text file. Parses the IP's in the text file for their DNS entry and exports to a CSV file. 
# For IP address' that do not resolve get parsed to a new file.
#
#
###########################################################

#This creates an ouput folder called Script_Results to put the results in.

    $CheckFolder = Test-Path -PathType Container Script_Results
    if($CheckFolder -eq $false)
    {
        New-Item 'Script_Results' -Type Directory
    }



#This gets the IP address' from the file

    $IPADDR = Get-Content "C:\Users\douglasfrancis\Desktop\IP_test.txt"



#This logic runs through each line in the text file to get the IP's perform a reverse DNS search and pulls the IP and hostname to be outputted and sorted later. It also ignores the errors from failed results

    $SortIP =@()
    ForEach ($IPADDR in $IPADDR)
    {
        $ErrorActionPreference = "SilentlyContinue"
        $SortIP += [System.Net.DNS]::GetHostbyAddress($IPADDR)  | Add-Member -Name IP -Value $IPADDR -MemberType NoteProperty -PassThru | Select Hostname, IP 
    }



#Running through the data from $SortIP sorts by hostname and exports to CSV

    $SortIP | Sort -Property Hostname | Export-Csv     "C:\Users\douglasfrancis\Desktop\Script_Results\ReverseLookup.csv" -NoTypeInformation



#Here we start to work some voodoo magic. Instead of attempting to parse the errors from the failed DNS results we're going to compare the orginal IP address txt file to the output file of the DNS
#By comparing those two files we can determine what files failed to resolve a DNS and output that to a file for review.

    #Here we're reimporting the exported CSV file of the DNS results. Pulling the IP address column from it and then exporting it again with only the IP info.
    Import-csv "C:\Users\douglasfrancis\Desktop\Script_Results\ReverseLookup.csv" | Select IP | Export-csv -Path "C:\Users\douglasfrancis\Desktop\Script_Results\OutputAddress.csv" -NoTypeInformation

    #Now for some futher voodoo data manipulation. Going to take the source IP address file import it back in as a CSV file with a IP column header.
    # After that we will then reexport it back again as a CSV file so a comparision can be done between the two files.
    Import-csv "C:\Users\douglasfrancis\Desktop\IP_Test.txt" -Header "IP" | Export-csv -Path "C:\Users\douglasfrancis\Desktop\Script_Results\InputAddress.csv" -NoTypeInformation

    #Alright just a bit more voodoo for some more data manipulation. Going to take those parsed data files from above and assign them to a var for further magic
    $OutputAddress = Import-csv "C:\Users\douglasfrancis\Desktop\Script_Results\OutputAddress.csv" -NoTypeInformation
    $SourceAddress = Import-csv "C:\Users\douglasfrancis\Desktop\Script_Results\InputAddress.csv" -NoTypeInformation


#Finally here we make use of all the voodo magic and do a comparison of data so we can find out what IP's failed to resolve via DNS and export that to the failed file.

    Compare-Object $OutputAddress $SourceAddress | Select InputObject | Export-csv "C:\Users\douglasfrancis\Desktop\Script_Results\ReverseLookup_failed.csv" -NoTypeInformation



#Alrighty, one final thing to do some housecleaning and we're outta here!

    Remove-Item "C:\Users\douglasfrancis\Desktop\Script_Results\InputAddress.csv"
    Remove-Item "C:\Users\douglasfrancis\Desktop\Script_Results\OutputAddress.csv"

Answer 1

Does this help solve your error handling problem?

$(ForEach ($IPADDR in $IPADDR)
    {
        Try {
             [System.Net.DNS]::GetHostbyAddress($IPADDR)  | 
              Select Hostname,@{label='IP';expression={$IPADDR}} 
            }

        Catch {
               Add-Content -Value "$IPADDR failed lookup" -Path "C:\Users\douglasfrancis\Desktop\Script_Results\ReverseLookup_failed.csv" 
              }

    }) | Sort -Property Hostname |
         Export-Csv "C:\Users\douglasfrancis\Desktop\Script_Results\ReverseLookup.csv" -NoTypeInformation