Portal detection methods

There are several ways to detect portals in Nethack. Portals count as a trap and can be found any way that a trap could be. This is most important on the Elemental and Astral Plane where speed is key. The usual methods are:


 * Read a cursed scroll of gold detection. This will show a pile of gold at every trap location.
 * Use a crystal ball and search for ^.
 * Zap a wand of secret door detection which will detect the portal if it is within a moderate radius.
 * Invoke the Amulet of Yendor, which will detect the portal if it is within a moderate radius.