Hi, I have created an external method that is called when I upload a file. This external method will execute the validate_file function from my python file in the Extensions directory. The script creates a file and tries to see if it contains a virus. It does run, but after creating the file, the os.system and os.remove commands do not seem to do anything. When I copy the relevant code from the script to a python file and run it on the server directly, the code works. Does anyone know what could be wrong? Thanks in advance! p.s. I am running Zope 2.6.1 with CMF 1.3 on a Linux box. ============= import os def validate_file(file): ''' Check is file contains a virus. ''' filename = "/usr/local/Zope/temp/temp.bin" # Write the file to the local filesystem temp = open(filename, "wb") temp.write(file.read()) temp.flush # Call virus checker error_level = os.system("f-prot " + filename) # Delete temp file os.remove(filename) return error_level;