macOS Retrieve MAC address

Program mac;

{$mode objfpc}{$H+}

Uses 
  SysUtils,
  StrUtils,
  Process,
  Classes;

function GetmacOSMacAddress : string;
var
   theProcess        : TProcess;
   theOutput         : TStringList;
   i, j, theLine, thePos : integer;

begin
   theProcess := TProcess.Create(nil);
   theProcess.Executable := 'ifconfig';

   // If interface specified, then retrieve its MAC address
   // Otherwise, retrieve MAC addresses for all interfaces
   if(ParamStr(1) <> '') then
      theProcess.Parameters.Add(ParamStr(1));

   theProcess.Options := theProcess.Options + [poWaitOnExit, poUsePipes];
   theProcess.Execute;
   theOutput := TStringList.Create;
   theOutput.LoadFromStream(theProcess.Output);

   theLine := -1;
   for i := 0 to theOutput.Count - 1 do
     begin
       j := pos('ether', theOutput.Strings[i]);
       if (j > 0) then
         begin
           theLine := i;
           thePos := j + length('ether') + 1;

           if(theLine > -1) then
              begin
                Result := UpperCase(ExtractSubStr(theOutput.Strings[theLine], thePos, [' ']));
                WriteLn(Result);
              end;
         end;
     end;

   // Always free the memory used
   theOutput.Free;
   theProcess.Free;
end;

begin
   GetmacOSMacAddress;
end.