Suppose that you want to calculate the space used by all the png files in current directory and all its subdirectories. From a terminal type:
find . -name '*.png' -exec du -ab {} \; | awk '{total+=$0}END{print total}'
Upload Progress with mod_python
Now that Gmail has added a progress bar for attachment uploads, everybody wants to do the same including myself 
So, with the same method that everybody uses consisting in an upload form with a hidden <iframe> as target, and then a periodic Ajax request to update the progress, I made a simple implementation using mod_python on the server side… This is a veeery simple example, like everything that you do with Python.
Additionally I’ve added an upload size limit control based in examples that can be found in the mod_python forum site. Use the source Luke!
See LIVE DEMO!
