如何使用Paramiko获取SSH返回码?

问题:如何使用Paramiko获取SSH返回码?

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

有什么方法可以获取命令返回码?

很难解析所有stdout / stderr并知道命令是否成功完成。

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

Is there any way to get the command return code?

It’s hard to parse all stdout/stderr and know whether the command finished successfully or not.


回答 0

SSHClient是一个简单的包装类,围绕着Paramiko中的更底层功能。该API文档列出recv_exit_status()的方法Channel类。

一个非常简单的演示脚本:

import paramiko
import getpass

pw = getpass.getpass()

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.WarningPolicy())
client.connect('127.0.0.1', password=pw)

while True:
    cmd = raw_input("Command to run: ")
    if cmd == "":
        break
    chan = client.get_transport().open_session()
    print "running '%s'" % cmd
    chan.exec_command(cmd)
    print "exit status: %s" % chan.recv_exit_status()

client.close()

执行示例:

$ python sshtest.py
Password: 
Command to run: true
running 'true'
exit status: 0
Command to run: false
running 'false'
exit status: 1
Command to run: 
$

SSHClient is a simple wrapper class around the more lower-level functionality in Paramiko. The API documentation lists a recv_exit_status() method on the Channel class.

A very simple demonstration script:

import paramiko
import getpass

pw = getpass.getpass()

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.WarningPolicy())
client.connect('127.0.0.1', password=pw)

while True:
    cmd = raw_input("Command to run: ")
    if cmd == "":
        break
    chan = client.get_transport().open_session()
    print "running '%s'" % cmd
    chan.exec_command(cmd)
    print "exit status: %s" % chan.recv_exit_status()

client.close()

Example of its execution:

$ python sshtest.py
Password: 
Command to run: true
running 'true'
exit status: 0
Command to run: false
running 'false'
exit status: 1
Command to run: 
$

回答 1

一个更简单的示例,该示例不涉及直接调用“较低级别”的通道类(即- 使用client.get_transport().open_session()命令):

import paramiko

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect('blahblah.com')

stdin, stdout, stderr = client.exec_command("uptime")
print stdout.channel.recv_exit_status()    # status is 0

stdin, stdout, stderr = client.exec_command("oauwhduawhd")
print stdout.channel.recv_exit_status()    # status is 127

A much easier example that doesn’t involve invoking the “lower level” channel class directly (i.e. – NOT using the client.get_transport().open_session() command):

import paramiko

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect('blahblah.com')

stdin, stdout, stderr = client.exec_command("uptime")
print stdout.channel.recv_exit_status()    # status is 0

stdin, stdout, stderr = client.exec_command("oauwhduawhd")
print stdout.channel.recv_exit_status()    # status is 127

回答 2

感谢JanC,我为示例添加了一些修改并在Python3中进行了测试,这对我来说真的很有用。

import paramiko
import getpass

pw = getpass.getpass()

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.WarningPolicy())
#client.set_missing_host_key_policy(paramiko.AutoAddPolicy())

def start():
    try :
        client.connect('127.0.0.1', port=22, username='ubuntu', password=pw)
        return True
    except Exception as e:
        #client.close()
        print(e)
        return False

while start():
    key = True
    cmd = input("Command to run: ")
    if cmd == "":
        break
    chan = client.get_transport().open_session()
    print("running '%s'" % cmd)
    chan.exec_command(cmd)
    while key:
        if chan.recv_ready():
            print("recv:\n%s" % chan.recv(4096).decode('ascii'))
        if chan.recv_stderr_ready():
            print("error:\n%s" % chan.recv_stderr(4096).decode('ascii'))
        if chan.exit_status_ready():
            print("exit status: %s" % chan.recv_exit_status())
            key = False
            client.close()
client.close()

Thanks for JanC, I added some modification for the example and tested in Python3, it really useful for me.

import paramiko
import getpass

pw = getpass.getpass()

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.WarningPolicy())
#client.set_missing_host_key_policy(paramiko.AutoAddPolicy())

def start():
    try :
        client.connect('127.0.0.1', port=22, username='ubuntu', password=pw)
        return True
    except Exception as e:
        #client.close()
        print(e)
        return False

while start():
    key = True
    cmd = input("Command to run: ")
    if cmd == "":
        break
    chan = client.get_transport().open_session()
    print("running '%s'" % cmd)
    chan.exec_command(cmd)
    while key:
        if chan.recv_ready():
            print("recv:\n%s" % chan.recv(4096).decode('ascii'))
        if chan.recv_stderr_ready():
            print("error:\n%s" % chan.recv_stderr(4096).decode('ascii'))
        if chan.exit_status_ready():
            print("exit status: %s" % chan.recv_exit_status())
            key = False
            client.close()
client.close()

回答 3

就我而言,输出缓冲是问题所在。由于存在缓冲,因此应用程序的输出不会以非阻塞方式输出。您可以在此处找到有关如何在不进行缓冲的情况下打印输出的答案:禁用输出缓冲。简而言之,只需使用-u选项运行python,如下所示:

> python -u script.py

In my case, output buffering was the problem. Because of buffering, the outputs from the application doesn’t come out non-blocking way. You can find the answer about how to print output without buffering in here: Disable output buffering. For short, just run python with -u option like this:

> python -u script.py