使用 popen 和专用 TTY Python 运行交互式 Bash
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Run interactive Bash with popen and a dedicated TTY Python
提问by TKKS
I need to run an interactive Bash instance in a separated process in Python with it's own dedicated TTY (I can't use pexpect). I used this code snippet I commonly see used in similar programs:
我需要在 Python 中的一个单独进程中运行一个交互式 Bash 实例，它有自己的专用 TTY（我不能使用 pexpect）。我使用了我在类似程序中经常看到的代码片段：
master, slave = pty.openpty()
p = subprocess.Popen(["/bin/bash", "-i"], stdin=slave, stdout=slave, stderr=slave)
os.close(slave)
x = os.read(master, 1026)
print x
subprocess.Popen.kill(p)
os.close(master)
But when I run it I get the following output:
但是当我运行它时，我得到以下输出：
$ ./pty_try.py
bash: cannot set terminal process group (10790): Inappropriate ioctl for device
bash: no job control in this shell
Strace of the run shows some errors:
运行的 Strace 显示了一些错误：
...
readlink("/usr/bin/python2.7", 0x7ffc8db02510, 4096) = -1 EINVAL (Invalid argument)
...
ioctl(3, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, 0x7ffc8db03590) = -1 ENOTTY (Inappropriate ioctl for device)
...
readlink("./pty_try.py", 0x7ffc8db00610, 4096) = -1 EINVAL (Invalid argument)
The code snippet seems pretty straightforward, is Bash not getting something it needs? what could be the problem here?
代码片段看起来很简单，是不是 Bash 没有得到它需要的东西？这里可能有什么问题？
采纳答案by TKKS
This is the solution that worked for me at the end (as suggested by qarma) :
这是最后对我有用的解决方案（如 qarma 所建议的）：
libc = ctypes.CDLL('libc.so.6')
master, slave = pty.openpty()
p = subprocess.Popen(["/bin/bash", "-i"], preexec_fn=libc.setsid, stdin=slave, stdout=slave, stderr=slave)
os.close(slave)
... do stuff here ...
x = os.read(master, 1026)
print x
回答by Liao
This is a solution to run an interactive command in subprocess. It uses pseudo-terminal to make stdout non-blocking(also some command needs a tty device, eg. bash). it uses select to handle input and ouput to the subprocess.
这是在子进程中运行交互式命令的解决方案。它使用伪终端使 stdout 非阻塞（还有一些命令需要 tty 设备，例如 bash）。它使用 select 来处理子进程的输入和输出。
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import os
import sys
import select
import termios
import tty
import pty
from subprocess import Popen
command = 'bash'
# command = 'docker run -it --rm centos /bin/bash'.split()
# save original tty setting then set it to raw mode
old_tty = termios.tcgetattr(sys.stdin)
tty.setraw(sys.stdin.fileno())
# open pseudo-terminal to interact with subprocess
master_fd, slave_fd = pty.openpty()
# use os.setsid() make it run in a new process group, or bash job control will not be enabled
p = Popen(command,
preexec_fn=os.setsid,
stdin=slave_fd,
stdout=slave_fd,
stderr=slave_fd,
universal_newlines=True)
while p.poll() is None:
r, w, e = select.select([sys.stdin, master_fd], [], [])
if sys.stdin in r:
d = os.read(sys.stdin.fileno(), 10240)
os.write(master_fd, d)
elif master_fd in r:
o = os.read(master_fd, 10240)
if o:
os.write(sys.stdout.fileno(), o)
# restore tty settings back
termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_tty)
