Powershell 1-liner to generate random n-byte key from Windows command line

powershell_command_urandom.js

// Windows equivalent to Linux/Mac: echo $(head -c 64 /dev/urandom | base64 | tr -d '\n')

// Get-Random in Windows 10/Server 2016 PowerShell uses a CSPRNG seed by default.
// Prior to PS 5.1, seed was system clock.

// For Win 10/2016+
powershell -command "[Convert]::ToBase64String((1..64|%{[byte](Get-Random -Max 256)}))"

// For Win 8.x/2012
powershell -command "$r=[byte[]]::new(64);$g=[System.Security.Cryptography.RandomNumberGenerator]::Create();$g.GetBytes($r);[Convert]::ToBase64String($r)"

This will produce a raw hex string, not Base64...
(1..64|%{[byte](Get-Random -Max 256)}|foreach ToString X2) -join ''