Powershell捕获循环输出到变量

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

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 2

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 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.