if I change hou.pwd() to hou.node('/obj/geo1/mdd')
and it will work!
have any body can help me?


import os
thisNode = hou.pwd()
inputNode = thisNode.inputs()
path = inputNode.evalParm('file')
newPath = os.path.splitext(path)
tmpPath =
tmpPath.append(str(newPath))
tmpPath.append('.mdd')
finalPath = ''.join(tmpPath)
print finalPath
return finalPath

hou.pwd() will evaluate the current path directory and works well when in a parameter field, callback script or in the script section of an HDA as it will return the path to the current node.

It won't work in the python shell as you have typed it and you need to supply a proper path.