backup.py

#!/usr/bin/env python3

import sys, os, subprocess

if len(sys.argv) != 2:
    raise SystemExit("Usage: {} USB_MOUNT_POINT".format(sys.argv[0]))

usb_mount_point = sys.argv[1]
home = os.path.expanduser("~")

files = ( 
    os.path.join(home, 'Desktop', 'data'), 
    os.path.join(home, 'Desktop', 'data2') 
)

for f in files:
    cmd = [ "rsync", "-az", f, usb_mount_point ]
    print(" ".join(cmd), "...", end="")
    try:
        subprocess.check_output(cmd, stderr=subprocess.STDOUT)
    except subprocess.CalledProcessError as e:
        print(" FAIL")
    else:
        print(" OK")