Python - capture Popen stdout AND display on console?

Question

I want to capture stdout from a long-ish running process started via subprocess.Popen(...) so I\'m using stdout=PIPE as an arg.

However, be

Answer 1

Inspired by pty.openpty() suggestion somewhere above, tested on python2.6, linux. Publishing since it took a while to make this working properly, w/o buffering...

def call_and_peek_output(cmd, shell=False):
    import pty, subprocess
    master, slave = pty.openpty()
    p = subprocess.Popen(cmd, shell=shell, stdin=None, stdout=slave, close_fds=True)
    os.close(slave)
    line = ""
    while True:
        try:
            ch = os.read(master, 1)
        except OSError:
            # We get this exception when the spawn process closes all references to the
            # pty descriptor which we passed him to use for stdout
            # (typically when it and its childs exit)
            break
        line += ch
        sys.stdout.write(ch)
        if ch == '\n':
            yield line
            line = ""
    if line:
        yield line

    ret = p.wait()
    if ret:
        raise subprocess.CalledProcessError(ret, cmd)

for l in call_and_peek_output("ls /", shell=True):
    pass