In the example a program named 'find' is executed without a shell. To launch the command in a shell pass 'shell=True' in the list of options
subprocess.call(['find', '/'], shell=True)
Catching STDOUT
To collect all output of a command executed use check_output()
output = subprocess.check_output(["ls"])
Redirecting STDERR
When you only want to redirect STDERR to STDIN and catch this output too, simply add 'stderr=subprocess.STDOUT' as an option when calling check_output()