在具有Sudo特权的远程服务器上运行Python脚本

Question

我了解了Python Pexcept软件包，以解决我在远程服务器上运行Python脚本作为root的问题，使用以下代码：

import pexpect

# Set the username for ssh connection
username = 'zod1@<remote-server-ip>'

# Take a valid password from the user
Password = input("Enter the login password of %s: " %username)

# Run ssh command using spawn
child = pexpect.spawn('ssh ' + username)

# Wait for the password
child.expect('password:')

# Send the password taken from the user
child.sendline(Password)

# Expected three output
i = child.expect (['Permission denied', 'Terminal type', '[#\$] '])

# i will be 0 if ssh is unable to connect
if i == 0:
    print("Permission denied by host. Unable to login")
    child.kill(0)

# i will be 1 if ssh is able to connect but terminal is not set
elif i == 1:
    print('Connected Successfully.\nTerminal type is not set.')
    child.sendline('vt100')
    child.expect('[#\$]')

# i will be 2 if ssh is able to connect and terminal is set
elif i == 2:
    print('Connected Successfully.')
    prompt = child.after
    print('Shell Command Prompt:', prompt.decode("utf-8"))

直到这里一切正常，但是我需要执行脚本的下一个部分（此处不包括此处） root用户，为此，我使用的是：

pwd = input("super user password: ")
child = pexpect.spawn('sudo su')
i = child.expect(['[sudo] password for zod1:']) 
child.sendline(pwd)

给出的：

Traceback (most recent call last):
  File "/Users/ravi3.intern/Desktop/new.py", line 131, in <module>
    i = child.expect(['[sudo] password for zod1:']) 
  File "/opt/homebrew/lib/python3.9/site-packages/pexpect/spawnbase.py", line 343, in expect
    return self.expect_list(compiled_pattern_list,
  File "/opt/homebrew/lib/python3.9/site-packages/pexpect/spawnbase.py", line 372, in expect_list
    return exp.expect_loop(timeout)
  File "/opt/homebrew/lib/python3.9/site-packages/pexpect/expect.py", line 181, in expect_loop
    return self.timeout(e)
  File "/opt/homebrew/lib/python3.9/site-packages/pexpect/expect.py", line 144, in timeout
    raise exc
pexpect.exceptions.TIMEOUT: Timeout exceeded.
<pexpect.pty_spawn.spawn object at 0x100c36f40>
command: /usr/bin/sudo
args: ['/usr/bin/sudo', 'su']
buffer (last 100 chars): b'Password:'
before (last 100 chars): b'Password:'
after: <class 'pexpect.exceptions.TIMEOUT'>
match: None
match_index: None
exitstatus: None
flag_eof: False
pid: 94531
child_fd: 6
closed: False
timeout: 30
delimiter: <class 'pexpect.exceptions.EOF'>
logfile: None
logfile_read: None
logfile_send: None
maxread: 1
ignorecase: False
searchwindowsize: None
delaybeforesend: 0.05
delayafterclose: 0.1
delayafterterminate: 0.1
searcher: searcher_re:
    0: re.compile(b'[sudo] password for zod1:'

这似乎被卡在child.sprect part上。我用“日期”而不是“ sudo su”测试了同一件事，这似乎在上述方法方面正常工作。因此，有人可以帮助调试错误。

Answer 1

您的搜索词期望与pexpect.before的输出不匹配，该输出是之前的（最后100个字符）：b'Password：'。您需要将该行更改为：

i=child.expect('Password:')

作为改进代码的另一个建议，您还可以在超时搜索，以便自己处理该异常。例如：

i=child.expect(['Password:',pexpect.TIMEOUT], timeout=5)
if i==0:
    child.sendline(Password)
elif i==1:
    print('Command failed to run, timeout')

Answer 2

以上脚本中的问题是：

1. i = child.expect（['[sudo] zod1：']）

   在这里
   找到匹配项，因为它会带来模式。

2. child = pexpect.spawn（'sudo su'）产生了一个新的独立过程
   而不是继续存在的过程。使用
   child.sendline（'sudo su'）解决了问题。