Powershell: Cannot read and write a variable on Hyperv-V VM from host-CodePudding

Using this Powershell script I try to write and read a variable on VM from host.

$Username = 'administrator'
$Password = 'password'
$pass = ConvertTo-SecureString -AsPlainText $Password -Force
$Cred = New-Object System.Management.Automation.PSCredential -ArgumentList $Username,$pass

#Added value to a variable on VM
Invoke-Command -VMName VM_Windows_2016 -Credential $Cred -ScriptBlock {$InstallPath="C:\Install\install-1.ps1"}
#Trying to read the variable on VM but with no result
Invoke-Command -VMName VM_Windows_2016 -Credential $Cred -ScriptBlock {Write-Host($InstallPath)}

As you see the result is empty. Can anyone help me to show how to write and read an variable on VM from host machine? Thanks!

CodePudding user response：

When using Invoke-Command to run a command remotely, any variables in the command are evaluated on the remote computer. So when you run the first Invoke-Command you are only defining the variable $InstallPath and terminating the remote PS session. When you are run the Invoke-Command second time it create entirely new PS session, hence InstallPath would be null. Instead of this you can define and read the variable in a single Cmdlet like this.

$remoteScriptblock = {
$InstallPath = "C:\Install\install-1.ps1"
Write-Host($InstallPath)
}
Invoke-Command -VMName VM_Windows_2016 -Credential $Cred -ScriptBlock $remoteScriptblock

If you still want to run this in multiple Cmdlets you may consider Run a command in a persistent connection