是否可以让pexpect输出与之匹配的文本? [英] Is it possbile to let pexpect output the texts it matches?

问题描述

我对Expect脚本很熟悉，因此当我第一次使用pexpect时会感到有些奇怪.以这个简单的脚本为例，

I am familiar with expect script so I feel a bit odd when I first use pexpect. Take this simple script as an example,

#!/usr/bin/expect
set timeout 10
spawn npm login
expect "Username:"
send "qiulang2000\r"
expect "Password:"
send "xxxxx\r"
expect "Email:"
send "[e-mail]\r"
expect "Logged in as"
interact

运行时，我将得到以下输出.感觉很自然，因为那是我运行这些命令的方式

When run it I will get the following output. It feels natural because that is how I run those commands

spawn npm login
Username: qiulang2000
Password:
Email: (this IS public) [e-mail]
Logged in as qiulang2000 on https://registry.npmjs.com/.

但是当我使用pexpect时，无论我如何添加print(child.after)或print(child.before)，我都无法获得期望的输出，例如当我运行以下命令时，

But when I use pexpect, no matter how I add print(child.after)or print(child.before) I just can't get output like expect, e.g. when I run following command,

#! /usr/bin/env python3
import pexpect
child = pexpect.spawn('npm login')
child.timeout = 10
child.expect('Username:')
print(child.after.decode("utf-8"))
child.sendline('qiulang2000')
child.expect('Password:')
child.sendline('xxxx')
child.expect('Email:')
child.sendline('[e-mail]')
child.expect('Logged in as')
print(child.before.decode("utf-8"))
child.interact()

我得到了这些输出，感觉不自然，因为那不是我在运行这些命令时看到的.

I got these output, it feels unnatural because that is not what I see when I run those commands.

Username:
 (this IS public)       [e-mail]

 qiulang2000 on https://registry.npmjs.com/.

那么有可能实现预期的脚本输出吗?

So is it it possbile to achieve the expect script output?

-更新---

有了我从@pynexj得到的评论，我终于使它生效了，请在下面检查我的答案.

With the comment I got from @pynexj I finally make it work, check my answer below.

推荐答案

有了我的评论，我终于使它起作用了

With the comment I got I finally made it work

#! /usr/bin/env python3

import pexpect
import sys
print('npm login',timeout = 10)
child = pexpect.spawn('npm login')
child.logfile_read = sys.stdout.buffer // use sys.stdout.buffer for python3
child.expect('Username:')
child.sendline('qiulang2000')
child.expect('Password:')
child.sendline('xxxx')
child.expect('Email:')
child.sendline('[e-mail]')
child.expect('Logged in as')

如果我需要调用child.interact()，那么在它之前调用child.logfile_read = None是很重要的，否则sys.stdout会回显我键入的所有内容.

If I need to call child.interact(), then it is important that I call child.logfile_read = None before it, otherwise sys.stdout will echo everything I type.

此处的答案如何在pexpect中查看输出?说我需要为python3传递编码，但是我发现如果使用encoding='utf-8'它将导致TypeError: a bytes-like object is required, not 'str'如果我根本不设置编码，一切都会正常.

The answer here How to see the output in pexpect? said I need to pass an encoding for python3, but I found that if I use encoding='utf-8' it will cause TypeError: a bytes-like object is required, not 'str' If I don't set encoding at all, everything works fine.

因此，一个简单的ssh登录脚本如下所示:

So a simple ssh login script looks like this

#!/usr/bin/env python3

import pexpect
import sys
child = pexpect.spawn('ssh qiulang@10.0.0.32')
child.logfile_read = sys.stdout.buffer
child.expect('password:')
child.sendline('xxxx')
#child.expect('Last login')  don't do that
child.logfile_read = None # important !!!
child.interact()

一个问题仍然没有解决，我在发送密码后添加了最后一个期望调用以匹配ssh登录输出，例如child.expect('最后登录')

One problem remains unresolved, I had added one last expect call to match the ssh login output after sending the password, e.g. child.expect('Last login')

但是，如果我添加了该行，则该行将显示两次.我放弃了尝试，就像一条评论说"pexpect的行为有点违反直觉".

But if I added that, that line would show twice. I have gave up trying, like one comment said "pexpect's behavior is kind of counter intuitive".

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