dd with progress in python

dd.py

#!/usr/bin/env python
import sys
import time
import signal
from subprocess import Popen, PIPE

dd = Popen(['dd'] + sys.argv[1:], stderr=PIPE)
while dd.poll() is None:
    time.sleep(.3)
    dd.send_signal(signal.SIGUSR1)
    while 1:
        l = dd.stderr.readline()
        if 'records in' in l:
            print l[:l.index('+')], 'records',
        if 'bytes' in l:
            print l.strip(), '\r',
            break
print dd.stderr.read(),

As dd doesn't seem to give any output (neither on stderr nor stdout) except when it's complete there's not much point in this (anymore?).

dd won't give you any progress output unless you give it an explicit status=progress option.