python - 如何使用 Paramiko 从远程机器上执行的命令中获取 stderr 返回值？

Question

请检查下面的代码(我认为这是不言自明的)。

代码:

import sys
import paramiko

def execute_command_on_remote_machine(ip_addr, command):
    try:
        client = paramiko.SSHClient()
        client.set_missing_host_key_policy(paramiko.AutoAddPolicy())

        client.connect(str(ip_addr), username='root', password='****')
        chan = client.get_transport().open_session()
        #chan.get_pty()

        stdin, stderr, stdout = [], [], []
        stdin, stdout, stderr = client.exec_command(command, get_pty=True)

        err_list = [line for line in stderr.read().splitlines()]
        out_list = [line for line in stdout.read().splitlines()]

        client.close()
        return out_list, err_list
    except Exception, e:
        print str(e)
        sys.exit(1)


output, error = execute_command_on_remote_machine("*.*.*.*", "dinesh")

print "Output is - ",output
print "Error is - ",error

输出:

D:\dsp_jetbrains\AWS_Persistence>python chk.py
Output is -  ['bash: dinesh: command not found']
Error is -  []

问题:

作为输入，我传递了一个不正确的命令，我预计“dinesh:command not found”将打印为“Error is”。但是，它带有“Output is”。

问题:

paramiko 中 exec_command 的输出和错误如何工作？

附加测试用例:

我还尝试使用存在的命令，但向该命令传递了错误的输入。示例 - lsof -f dinesh

但结果是一样的。

D:\dsp_jetbrains\AWS_Persistence>python chk.py
Output is -  ['lsof: unknown file struct option: d', 'lsof: unknown file struct
option: i', 'lsof: unknown file struct option: n', 'lsof: unknown file struct op
tion: e', 'lsof: unknown file struct option: s', 'lsof: unknown file struct opti
on: h', 'lsof 4.87', ' latest revision: ftp://lsof.itap.purdue.edu/pub/tools/uni
x/lsof/', ' latest FAQ: ftp://lsof.itap.purdue.edu/pub/tools/unix/lsof/FAQ', ' l
atest man page: ftp://lsof.itap.purdue.edu/pub/tools/unix/lsof/lsof_man', ' usag
e: [-?abhKlnNoOPRtUvVX] [+|-c c] [+|-d s] [+D D] [+|-f[gG]] [+|-e s]', ' [-F [f]
] [-g [s]] [-i [i]] [+|-L [l]] [+m [m]] [+|-M] [-o [o]] [-p s]', '[+|-r [t]] [-s
 [p:s]] [-S [t]] [-T [t]] [-u s] [+|-w] [-x [fl]] [-Z [Z]] [--] [names]', "Use t
he ``-h'' option to get more help information."]
Error is -  []

Answer 1

你可能不应该使用 get_pty 除非你知道你需要它。考虑删除:

chan.get_pty()

和改变:

stdin, stdout, stderr = client.exec_command(command, get_pty=True)

到:

stdin, stdout, stderr = client.exec_command(command)

来自DOCS :

Request a pseudo-terminal from the server. This is usually used right after creating a client channel, to ask the server to provide some basic terminal semantics for a shell invoked with invoke_shell. It isn’t necessary (or desirable) to call this method if you’re going to exectue a single command with exec_command.

A pseudo-terminal如果您希望您的 ssh 连接看起来像用户已连接，则使用它。很少需要这个。一个人为的例子是，如果您想通过发送和接收 ansi 终端序列在远端使用 VIM。

如果没有 get_pty，远程执行的命令将简单地连接 stdin/stdout/stderr 三重奏，就像在管道中一样。

很少需要 get_pty 可能是它不是默认设置的原因。