How to expand variable in powershell?

Question

Get-WmiObject -Class win32_logicaldisk -Filter \'DeviceID=\"C:\"\'

does what I want,

$var=\"C:\"
Get-WmiObject -Class win32_logical         


        

Answer 1

I didn't find expanding expressions in PowerShell, but here's what I found.

# Let's set some varaible
$ComputerName = 'some-value'

# Let's store this variable name
$name = 'ComputerName'

# Get value by `Get-Item`.
(Get-Item variable:$name).Value # throws an exception for undefined variables.

# Get value by `Invoke-Expression`
Invoke-Expression "`$variable:$name"
Invoke-Expression "`$$name"

The same but for environment variables

(Get-Item env:$name).Value # throws an exception for undefined environments.
Invoke-Expression "`$env:$name"

I prefer Get-Item as it "fails loudly".

And Get-Item allows to use additional literals during this process, as well as Invoke-Expression.
I.e. see the Computer literal below before the $ sign.

$otherName = 'Name'

(Get-Item variable:Computer$otherName).Value
(Get-Item env:Computer$otherName).Value