What does $_ mean in PowerShell?

Question

I\'ve seen the following a lot in PowerShell, but what does it do exactly?

$_

Answer 1

This is the variable for the current value in the pipe line, which is called $PSItem in Powershell 3 and newer.

1,2,3 | %{ write-host $_ } 

or

1,2,3 | %{ write-host $PSItem } 

For example in the above code the %{} block is called for every value in the array. The $_ or $PSItem variable will contain the current value.