Powershell capturing loop output to a variable - powershell

Question

Hi guys im having issues getting my head around how I capture ping response to a variable if that makes sense. As i want to be able to output back to a csv with the response. Of course there is a very good chance im approaching this in totally the wrong way !
$PingMachines=import-Csv -path C:\temp\pcs.csv -Header cn,operatingsystem,LastLogonDate
foreach ($pc in $pingmachines.cn) {
$PingStatus = Gwmi Win32_PingStatus -Filter "Address = '$pc'" | `
Select-Object StatusCode
If ($PingStatus.StatusCode -eq 0){
Write-Host $pc "up"
}
Else {
Write-Host $pc "down"
}
}
In an ideal world id love to be able to save the output ie pc,pingstatus.statuscode back to a variable but im struggling with the logic and how to increment to the variable rather than just having the last object.
Thanks in advance.

Answer 1

Use the Win32_PingStatus WMI object, as it already contains the data you need. When you pipe gwmi result to Select-Object, you remove all but StatusCode.
Consider
$PingStatus = Gwmi Win32_PingStatus -Filter "Address = '$pc'" | Select-Object StatusCode
$PingStatus # Contains only StatusCode
Output:
StatusCode
----------
0
Whereas the WMI class contains more members:
$PingStatus = Gwmi Win32_PingStatus -Filter "Address = '$pc'"
$PingStatus # Contains a lot more
Output:
Source Destination IPV4Address IPV6Address Bytes Time(ms)
------ ----------- ----------- ----------- ----- --------
MyPC Server 10.0.0.1 {} 32 1

Answer 2

I rewrote your code a bit; this works for me:
$machines = import-csv -path machines.csv -header ip,os,LastLogonDate
foreach ($machine in $machines)
{
$ip = $machine.ip
$status = gwmi win32_PingStatus -filter "Address = '$ip'"
if ($status.StatusCode -eq 0)
{ Write-Host $ip 'up' }
else
{ Write-Host $ip 'down' }
}
I tested it out on a file machines.csv that looks like this:
"127.0.0.1","linux","2012-1-1"
"192.168.1.93","minux","2012-2-10"
"192.168.1.254","xenix","2012-3-20"
"192.168.1.66","dynix","2012-4-5"
When I run it, the output looks something like this:
PS C:\Users\dharmatech\Documents> C:\Users\dharmatech\Documents\check-machine-status.ps1
127.0.0.1 up
192.168.1.93 up
192.168.1.254 up
192.168.1.66 up

Answer 3

Use the pipeline with ForEach-Object instead of the foreach( in ) construct. Using ForEach-Object will run the commands as part of the pipeline, which will allow you to capture the output as a variable.
$PingMachines=import-Csv -path C:\temp\pcs.csv -Header cn,operatingsystem,LastLogonDate
$PingMachines.cn | ForEach-Object {
$PingStatus = Gwmi Win32_PingStatus -Filter "Address = '$_'" | `
Select-Object StatusCode
If ($PingStatus.StatusCode -eq 0){
Write-Host $_ "up"
}
Else {
Write-Host $_ "down"
}
}
You can think of the pipeline version's $_ automatic variable like this:
foreach( $_ in $PingMachines.cn) {
#code that uses $_
}
Once you have a pipeline going, you'll need to output an object instead of just printing to the screen using Write-Host:
$PingMachines=import-Csv -path C:\temp\pcs.csv -Header cn,operatingsystem,LastLogonDate
$PingResults = $PingMachines.cn | ForEach-Object {
$PingStatus = Gwmi Win32_PingStatus -Filter "Address = '$_'" | `
Select-Object StatusCode,Address
#I added the Address property above so you would have the machine name in the output object
If ($PingStatus.StatusCode -eq 0){
Write-Host $_ "up"
}
Else {
Write-Host $_ "down"
}
#Send the $PingStatus object out on the pipeline, which will end up in $PingResults
Write-Output $PingStatus
}
June Blender recently posted a good article on powershell.org that covers outputting objects vs Write-Host and creating custom objects so I won't go into the full detail here.