Mock the bash export function in powershell

mock-bash.ps1

function Set-EnvironmentVariable($key, $value) {
  Set-Content -Value $value -Path ("env:" + $key)
  New-Variable -Scope Global -Name $key -Value $value -Force
}

function export($envVar) { 
    $split = $envVar.Trim().Split("=");
    Set-EnvironmentVariable $split[0] $split[1]    
}

function Decrypt-SecureString {
  param(
      [Parameter(ValueFromPipeline=$true,Mandatory=$true,Position=0)]
      [System.Security.SecureString]
      $sstr
  )
  if(!$sstr) {
    return
  }
  
  $marshal = [System.Runtime.InteropServices.Marshal]
  $ptr = $marshal::SecureStringToBSTR( $sstr )
  $str = $marshal::PtrToStringBSTR( $ptr )
  $marshal::ZeroFreeBSTR( $ptr )
  $str
}

function read($prompt=$null, $sr=$null) {
  $result; 
  $command = "Read-Host"
  if ($prompt) {
    $command += " -Prompt " + $prompt.ToString()
  }
  
  if ($sr) {
    $command += " -AsSecureString"
  }
  
  $result = Invoke-Expression $command
  
  if ($sr) {
    $result = $result | Decrypt-SecureString
    Set-EnvironmentVariable $sr $result | Out-Null
  }
  else {
    return $result;
  }
}