Lease stability

If you have a valid lease and the property gets closed on during a short sale, is the lease still valid and transferable ?
Does teh tenant have to vacat ?
How long is the lease valid for ?

is a lease mandatory to honor by the purchaser of a short sale ?

Unless there is a provision or clause in the lease to the contrary, leases must be honored by the new owner, i.e. leases go with the property in a short sale or a normal sale.