Show Users Logons per Computer Names

# This script is to obtain log on information from a set of target computernames and/or IP addresses.

# Update this value
$ComputerList = "\\FILESERVER01\IT\scripts\computerlist.txt"

function CheckForWMI {
#The line below checks for WMI, if no WMI then the command failed, which makes $? = false. The out-null kills any screen output.
trap {; Continue}; 
$Script:Win32_ComputerSystem = GWMI Win32_ComputerSystem -ea SilentlyContinue -computer $computername
if ($? -eq $False) {$Script:HasWMI = $FALSE} else {$Script:HasWMI = $TRUE}
}

function Get-ComputerLoggedOnCurrently {
$Script:ComputerLoggedOnCurrently = $Win32_ComputerSystem.UserName;
if ($ComputerLoggedOnCurrently -eq "") {$ComputerLoggedOnCurrently = "---"}
}

function TwoHalfLines {1..2 | % {for ($i=0;$i -lt $width/2; $i++) {Write-host -f cyan "-" -nonewline;};write-host "";} }

function Get-IPorComputerNameFromDNS {
param($computer)
if ($computer -match "^\d" ) {
$Script:ip = $computer
trap {; continue}; $Script:DnsResult = [System.Net.Dns]::GetHostByAddress($Computer)
trap {; continue}; $Script:ComputerName = $DnsResult.HostName.split(".")[0]
} else {
$Script:ComputerName = $computer
trap {; continue}; $Script:DnsResult = [System.Net.Dns]::GetHostByName($Computer)
trap {; continue}; $Script:ip = $DnsResult.AddressList[0].IpAddressToString
}
}

function ProcessListOfComputers {
$ComputerName = $null;
$Script:ComputerNameList = $(get-content $ComputerList)
$Script:ComputerNameListCount = $ComputerNameList.Length
$Script:ComputerListNumber = 0;
$ComputerName = $ComputerNameList[$ComputerListNumber]
if ($ComputerName -eq "") {
do {
$Script:ComputerListNumber++
$Script:ComputerName = $ComputerNameList[$ComputerListNumber]
} until ($ComputerName -ne $null -or $ComputerName -eq "EOF")
}
if ($ComputerName -eq "EOF") {QuitScript "No computers listed in the imported file." "red" "white"}
Get-IPorComputerNameFromDNS $ComputerName
}

function NextIP {
$Script:ComputerListNumber++
$Script:ComputerName = $ComputerNameList[$ComputerListNumber]
if ($ComputerListNumber -eq $ComputerNameListCount -or $ComputerName -eq "EOF") {$Script:stop = $TRUE}
Get-IPorComputerNameFromDNS $ComputerName
}

# Execution begins
Clear-Host
if ((Test-Path $ComputerList) -eq $FALSE) {Add-Content -Path $ComputerList -value "`nEOF"}
$ping = New-Object System.Net.NetworkInformation.Ping
$width = $Host.UI.RawUI.BufferSize.width
clear-host
TwoHalfLines
ProcessListOfComputers
do {
$Script:ComputerLoggedOnCurrently = $null;
Write-Host -f yellow "IP address:`t`t`t`t" -nonewline; Write-Host -f green "$ip";
$Processed_IP = $ip
Write-Host -f yellow "Reading information on computer:`t" -nonewline; write-host -f green "$ComputerName";
$ProcessedComputerName = $computername
$PingReply = $ping.Send($ip)
if ($PingReply.status -eq "Success") {
CheckForWMI; start-sleep -m 300
if ($HasWMI -eq $TRUE) {
Get-ComputerLoggedOnCurrently
Write-Host -f yellow "Logged On Currently:`t`t" -nonewline; Write-host -f green "`t$ComputerLoggedOnCurrently`n"
$computername = $null
NextIP
} else {write-host -f red "`tUnable to access WMI. Computer may not have WMI, or`n`tscript was unable to get a computername from DNS."; $ComputerLoggedOnCurrently = "N/A - WMI not accessible."; NextIP }
} else {Write-host -f red "`tCan not ping $ComputerName-$ip."; $ComputerLoggedOnCurrently = "N/A - Computer not pingable."; NextIP }

if ($Results -eq $null) {$Results = ,("$Processed_IP","$ProcessedComputerName","$ComputerLoggedOnCurrently")} `
else {$Results += ,("$Processed_IP","$ProcessedComputerName","$ComputerLoggedOnCurrently")}
} until ($stop -eq $TRUE)
TwoHalfLines
1..4 | % {write-host "`n"}
write-host -f green "Computer Name`t`tIP Address`t`tLogged on"
foreach ($line in $Results) {
write-host -f yellow "$($line[1])`t`t`t$($line[0])`t`t$($line[2])"
}
1..5 | % {write-host "`n"}