Here's another test, taken from the docs:

http://docs.python.org/library/subprocess.html#subprocess-replacements:

This is slightly better than Popen because the program executes and
shows output, but worse than os.system(), because it still shows the error:

--------------------------
try:
            retcode = call("echo" + " \"hello world\"", shell=True)
            if retcode < 0:
                print >>sys.stderr, "Child was terminated by signal",
-retcode
                print >>sys.stderr, "Child was terminated by signal",
-retcode
            else:
                print >>sys.stderr, "Child returned", retcode
        except OSError, e:
            print >>sys.stderr, "Execution failed:", e


-----------------
hello world
Execution failed: [Errno 10] No child processes