Python中subprocess管道传递密码至getpass脚本失败求助

我尝试用main.py脚本通过管道标准输入给password.py传密码，但password.py用getpass.getpass()获取用户输入，用subprocess子进程管道输入时出现错误，没法完成密码传递。希望实现自动化流程，不用每次手动输入密码。

相关代码 #

password.py #

import getpass

password = getpass.getpass("Enter your password: ")
if password != "test":
    print("wrong password")
else:
    print("correct password")

main.py（原出错版本） #

import subprocess as sp

# 启动password.py作为子进程
proc = sp.Popen(["python", "password.py"], stdin=sp.PIPE, stdout=sp.PIPE, stderr=sp.PIPE)

# 读取输出和错误流
stdout, stderr = proc.communicate()

# 打印结果
print(stdout)
print(stderr)

# 等待进程结束并获取返回码
returncode = proc.wait()

# 检查返回码
if returncode == 0:
    print("Command successful")
else:
    print("Command failed")

报错信息 #

b'/usr/lib/python3.8/getpass.py:91: GetPassWarning: Can not control echo on the terminal.\n  
passwd = fallback_getpass(prompt, stream)\nWarning: Password input may be echoed.\nEnter your password: Traceback (most recent call last):\n  
File "/usr/lib/python3.8/getpass.py", line 69, in unix_getpass\n  
  old = termios.tcgetattr(fd)     # a copy to save\ntermios.error: (25, \'Inappropriate ioctl for device\')\n\n
During handling of the above exception, another exception occurred:\n\nTraceback (most recent call last):\n  
File "password.py", line 3, in <module>\n    password = getpass.getpass("Enter your password: ")\n  
File "/usr/lib/python3.8/getpass.py", line 91, in unix_getpass\n    passwd = fallback_getpass(prompt, stream)\n  
File "/usr/lib/python3.8/getpass.py", line 126, in fallback_getpass\n    return _raw_input(prompt, stream)\n  
File "/usr/lib/python3.8/getpass.py", line 148, in _raw_input\n    raise EOFError\nEOFError\n'
Command failed

原因 #

getpass.getpass()的设计逻辑是直接与终端交互，而非从标准输入读取内容。当子进程的stdin被重定向到管道时，它无法正常控制终端的回显行为，最终抛出终端控制相关的错误并触发EOFError。

解决方案 #

方案1：修改password.py，支持从环境变量获取密码（推荐，最简单） #

如果允许修改password.py，可以让它优先从环境变量读取密码，没有的话再用getpass手动输入：

import getpass
import os

# 优先读取环境变量MY_PASSWORD，不存在则使用getpass
password = os.environ.get('MY_PASSWORD') or getpass.getpass("Enter your password: ")
if password != "test":
    print("wrong password")
else:
    print("correct password")

对应的main.py修改为：

import subprocess as sp
import os

# 复制当前环境变量，添加密码
env = os.environ.copy()
env['MY_PASSWORD'] = 'test'

# 启动子进程并传递环境变量
proc = sp.Popen(["python", "password.py"], stdout=sp.PIPE, stderr=sp.PIPE, env=env)
stdout, stderr = proc.communicate()

# 解码并打印输出
print(stdout.decode())
print(stderr.decode())

returncode = proc.wait()
if returncode == 0:
    print("Command successful")
else:
    print("Command failed")

方案2：用伪终端（pty）模拟终端交互（无需修改password.py） #

如果不能修改password.py，可以用pty模块创建伪终端，让getpass以为在和真实终端交互：

import subprocess as sp
import pty
import os

# 创建伪终端主从设备
master, slave = pty.openpty()

# 启动子进程，将标准输入输出绑定到伪终端
proc = sp.Popen(["python", "password.py"], stdin=slave, stdout=slave, stderr=slave)
os.close(slave)  # 关闭不必要的从设备

# 向伪终端写入密码，记得加换行符模拟回车
os.write(master, b'test\n')

# 读取输出内容
output = os.read(master, 1024).decode()
os.close(master)

# 等待进程结束并检查返回码
returncode = proc.wait()

print(output)
if returncode == 0:
    print("Command successful")
else:
    print("Command failed")

内容的提问来源于stack exchange，提问作者Rabia Hussain