返回通过嵌入在 python 内的 expect 命令中的 ssh 远程执行的 grep 命令的状态

Question

我有一个下面的 python 脚本，我在其中使用 expect 执行远程 SSH 命令。在这里，即使目标文件包含字符串“error”或不包含，退出代码总是作为成功返回，因为 ssh 连接是唯一的检查。如何获取 grep 命令的状态？

#! /usr/bin/python

import subprocess

def execute(cmd):
    proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    _output, _error = proc.communicate()
    _code = proc.returncode
    return _output, _error, _code

host = "localhost"
passwd = "kube"

cmd="/usr/bin/expect -c 'spawn ssh "+host+" \"cat /home/kube/f1 | grep -qi error\"; expect \"password:\" { send \""+passwd+"\r\"} ;interact' "
_output, _error, return_code = execute(cmd)
print cmd + "\n" + _output + "\n" + _error

if (return_code == 0):
    print "no error"
else:
    print "contains error"

Answer 1

选项 1：

让远程命令为你输出一些指示success/failure的东西。例如：

ssh user@host "/some/command | grep -q some-string && echo MAGIC-SUCCESS || echo MAGIC-FAILURE"

并且在 Python 中您可以获得输出并解析它。

选项 2：

根据man expect：

wait [args]

[...] wait normally returns a list of four integers. The first integer is the pid of the process that was waited upon. The second integer is the corresponding spawn id. The third integer is -1 if an operating system error occurred, or 0 otherwise. If the third integer was 0, the fourth integer is the status returned by the spawned process. If the third integer was -1, the fourth integer is the value of errno set by the operating system. [...]

因此您的 Expect 代码可以检查 wait 结果，然后 exit 具有不同的值，并且 Python 代码可以获得退出状态。

对于 Expect 部分，它是这样的：

spawn ...
...
expect eof
set result [wait]
exit [lindex $result 3]

返回通过嵌入在 python 内的 expect 命令中的 ssh 远程执行的 grep 命令的状态

Returning status of grep command executed remotely via ssh embedded in expect command inside python

python

ssh

expect

选项 1：

选项 2：