Scripting: Armatures
Offical API-Doc Links:
Get a list by
armatures = [obj for obj in bpy.context.scene.objects if obj.type=="ARMATURE"]
Armature
Check bones like this
obj=armatures[0]
# all bones
for b in obj.data.bones:
print(b.name)
# active
print(obj.data.bones.active)