Is “Dollar-sign” optional in powershell “$()”?

Question

I\'ve seen an example for setting the timestamps (creationtime, lastaccesstime, lastwritetime) of a file with powershell:

PS>$(get-item test.txt).lastwritetim         


        

Answer 1

You need the $ sign to denote a sub expression if you use multiple statements or the statement is embedded in a string. Parenthesis without the $ is just a grouping operator.

$($x = 1; $y =2; $x + $y).tostring() //3

($x = 1; $y =2; $x + $y).tostring() // invalid syntax

($x = 1 + 2).tostring() //3

"$(1 +2)"  //3

Answer 2

The first time I need of $() was inside a string :

$a = Get-Process "explorer"
Write-host "$a.Name" -> System.Diagnostics.Process (explorer).Name
Write-Host "$($a.Name)" -> explorer

I also use it each time I want PowerShell to force compute something first.