I have some code to calculate the size of an oracle export dump. I can run the command from the command line; however, in the jython script it hangs and does not return control to the screen. I have to perform a ctrl-C and clean up the processes. I have tried os.system(cmd) to run this code, popen2.popen3, and os.poen. My goal is to write the number of block to a file. Thanks in advance

here's a sample of my code.
Code:
#!/usr/bin/env
...