python输出命令行的信息-实时的

import os
import subprocess
from subprocess import Popen, PIPE
# run the shell as a subprocess: 
cmd2 = "pint www.baidu.com"
import os
import pty
import select
from subprocess import Popen, STDOUT

master_fd, slave_fd = pty.openpty()  # provide tty to enable
                                     # line-buffering on ruby's side
proc = Popen(command,
             stdout=slave_fd, stderr=STDOUT, close_fds=True)
timeout = .04 # seconds
while 1:
    ready, _, _ = select.select([master_fd], [], [], timeout)
    if ready:
        data = os.read(master_fd, 512)
        if not data:
            break
        print("got " + repr(data))
    elif proc.poll() is not None: # select timeout
        assert not select.select([master_fd], [], [], 0)[0] # detect race condition
        break # proc exited
os.close(slave_fd) # can't do it sooner: it leads to errno.EIO error
os.close(master_fd)
proc.wait()

print("This is reached!")