PowerShell/CLI: "Foreach" loop with multiple arrays

Question

I have a PowerCLI script that powers off a VM, changes its memory and cpu, and then powers it back on. I've adapted the script to utilize variables. This all works perfectly.

I'm now trying to modify the script to utilize arrays, in order to cycle through numerous VMs. The script portions that powers off and powers on the VMs works perfectly.

The trouble I'm having is using variables from two arrays in a foreach loop.

For each VM in $vm_name, I need to set the corresponding amount of memory found in $memory_gb.

This is what I have (it currently sets the same amount of memory ("1") for all of the VMs)....

$vm_name = @("OMAC-SBXWIN7AJM", "OMAC-SBXWIN2012R2AJM", "OMAC-SBXWIN2008R2AJM")
$memory_gb = 2,4,4

# SET THE VM MEMORY
Write-Host 'NOW SETTING THE VM MEMORY'
foreach ($objItem in $vm_name)
{Set-VM -VM $vm_name -MemoryGB 1 -confirm:$false 
Break
}

https://i.sstatic.net/E9hfY.png

...I've tried nesting a second foreach loop inside of the first, to no avail.

How do write the script so each VM in $vm_name, gets the corresponding amount of memory found in $memory_gb?

Crosspatch

Answer 1

You have 2 options. First (and not what I would suggest) is a For() loop. It would go something like this:

For($I=0;$I -lt $vm_name.count;$I++){
    Set-VM -VM $vm_name[$I] -MemoryGB $memory_gb[$I] -confirm:$false
}

The better way would be to put it in a CSV with headers like VMName, Memory and then list each VM and the memory you want in it. Then run something like:

Import-CSV C:\Path\To\File.CSV | ForEach{Set-VM -VM $_.VMName -MemoryGB $_.memory -confirm:$false}

Unbolt

Putting it into a data file is quite clever, hats off. – Kerrill

This worked perfectly. Thank you! I will certainly be using a .CSV, as Ill eventually be modifying numerous machines. – Crosspatch

This worked, but I got this error.... Set-VM : Cannot bind parameter 'MemoryGB' to the target. Exception setting "MemoryGB": "Object reference not set to an instance of an object." At U:\How To\PowerCLI\Test.ps1:8 char:36 + Set-VM -VM $vm_name[$i] -MemoryGB $memory_gb[$i] -confirm:$false + ~~~~~~~~~~~~~~ + CategoryInfo : WriteError: (:) [Set-VM], ParameterBindingExcept ion + FullyQualifiedErrorId : ParameterBindingFailed,VMware.VimAutomation.ViCo re.Cmdlets.Commands.SetVM Since it worked, does the error really matter? – Crosspatch

That's probably because I used -le instead of -lt so it was trying to iterate a 4th VM/memory set. I really expected you to utilize the second option, so I didn't pay as close of attention as I should have on the first one. I'll update the answer shortly to rectify that. – Unbolt

Answer 2

You can use Zip function:

function Zip($a1, $a2) {
    while ($a1) {
        $x, $a1 = $a1
        $y, $a2 = $a2
        [tuple]::Create($x, $y)
    }
}

Usage:

zip 'a','b','c' 1,2,3 |% {$_.item1 + $_.item2}

Result:

a1
b2
c3

Celiaceliac

@js2010 to clear it up for future readers: the $x, $a1 = $a1 syntax is unpacking the next member of the array instead of keeping a manual iterator $i or similar – Supply

Answer 3

$vm_name = @("OMAC-SBXWIN7AJM", "OMAC-SBXWIN2012R2AJM", "OMAC-
SBXWIN2008R2AJM")
$memory_gb = 2,4,4

# SET THE VM MEMORY
Write-Host 'NOW SETTING THE VM MEMORY'
foreach ($objItem in $vm_name)
{
    Set-VM -VM $vm_name -MemoryGB $memory_gb[$vm_name.indexOf($objItem)] -confirm:$false 
    Break
}

This will work as long as the two arrays are the same size.

Sinking

you sir are a gentleman and a scholar, i could not figure out how to pass two array type variables to a foreach loop without it doing each array item on the other array items each time. so something that should have ran 4 loops was doing 16. But this part saved me: [$vm_name.indexof($objItem)] – Storekeeper

Index of is a pretty clever solution. – Sandon

Answer 4

Another, more compact, solution is to use a hashtable:

$vms = @{"OMAC-SBXWIN7AJM" = 2; "OMAC-SBXWIN2012R2AJM" = 4; "OMAC-SBXWIN2008R2AJM" = 4}

# SET THE VM MEMORY
Write-Host 'NOW SETTING THE VM MEMORY'
foreach ($vm in $vms.getEnumerator()){
    Set-VM -VM $vm.Name -MemoryGB $vm.Value -confirm:$false 
}

Sciatic

This also worked for me. Thanks! I hadnt considered uses a hash table. – Crosspatch

Answer 5

$vm_name = @("OMAC-SBXWIN7AJM", "OMAC-SBXWIN2012R2AJM", "OMAC-SBXWIN2008R2AJM")
$memory_gb = (2,4,4)

# SET THE VM MEMORY
Write-Host 'NOW SETTING THE VM MEMORY'
for( $i = 0; $i -lt $vm_name.length; $i++) {
  $vm = $vm_name[$i]
  $gb = $memory_gb[$i]
  write-host setting $vm to $gb GB ...
  Set-VM -VM $vm -MemoryGB $gb -confirm:$false 
}

You just need to ensure both arrays are of the same length.

Kerrill

Thanks JesG. This provides the easiest to remember solution for me. – Another