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(),

This rocks, thanks.

As a Python3 module:

#!/usr/bin/env python3

import time, signal, subprocess

def run_dd(*args):
    cmd = ['dd', *args]
    dd = subprocess.Popen(cmd, stderr=subprocess.PIPE)
    while dd.poll() is None:
        time.sleep(.3)
        dd.send_signal(signal.SIGUSR1)
        while True:
            l = dd.stderr.readline()
            if b'records in' in l:
                print(l[:l.index('+')], 'records')
            if b'bytes' in l:
                print(l.strip(), '\r')
                break
    print(dd.stderr.read())

if __name__ == '__main__':
    from sys import argv
    run_dd(*argv[1:])

Usage:

import dd
dd.run_dd('if=/dev/sda', 'of=/dev/sdb', 'status=progress')

The code seems to hang on the line with stderr.readline.

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.