code: private static String getMacUserShell()
          throws EnvironmentException
      {
          if( null != m_SHELL )
          {
              return m_SHELL;
          }
          String[] args = { "nidump", "passwd", "/" };
          return readShellFromPasswdFile( args );
      }
docs: Gets the default login shell used by a mac user.
  
  @return the Mac user's default shell as referenced by cmd:
  'nidump passwd /'
  
  @throws EnvironmentException if os information is not resolvable