python pexpect类型字符串代码我终端应用程序

Question

我正在尝试使用 python 的终端应用程序， 运行应用程序后，此应用程序要求输入相同的单词。

这是我当前的代码：

import pexpect
import sys

child = pexpect.spawn("./helium-wallet create basic --seed mobile")
child.logfile_read = sys.stdout.buffer
child.expect("Space separated seed words: ")
child.sendline("carpet again stick economy finish recipe blouse forward program stumble need ginger")
# don't warry about my seed, is just a example.

print(child.before)

发送文字后，应用返回此错误：

(base) admin@192-168-0-181 helium-wallet-v1.6.10-x86-64-macos % python prova.py                           
Space separated seed words: b''

看起来像python发送一个字节单词，而不是字符串...... 我如何发送字符串？

Answer 1

您从未将 pexpect 光标向前移动。 sys.stdout.buffer 回应了提示，所以这就是 before 显示的内容。注释掉child.logfile_read = sys.stdout.buffer，你会得到b''。

要向前移动缓冲区，您有两种选择：

注意 - 使用 Python 3.8 在 Ubuntu 20.04 上测试

1. 如果您不必再输入任何数据，请使用child.read() 让程序运行；光标会自动向前移动。一旦read 遇到EOF（程序终止），logfile_read 将显示所有输出到 STDOUT：

父级（parent.py）：

import pexpect
import sys

# helium-wallet.py is just a quick script I wrote to mimic your script
print("Parent: Running the child.")
child = pexpect.spawn("python3 helium-wallet.py")
child.logfile_read = sys.stdout.buffer
child.expect("Space separated seed words: ")
child.sendline("carpet again stick economy finish recipe blouse forward program stumble need ginger")
child.read()
print("Parent: Script complete. Have a nice day.")

子 (helium-wallet.py)：

text = input("Child: Space separated seed words: ")
print("Child: Did something with:", text)
print("Child: Script complete. Have a nice day.")

输出：

Parent: Running the child.
Child: Space separated seed words: carpet again stick economy finish recipe blouse forward program stumble need ginger
Child: Did something with: carpet again stick economy finish recipe blouse forward program stumble need ginger
Child: Script complete. Have a nice day.
Parent: Script complete. Have a nice day.

2. 如果您要输入更多数据（即，您需要孩子活着），请使用child.expect()（我删除了logfile 回显；将其与before 一起使用使输出混乱）：

父级（parent.py）：

import pexpect

# helium-wallet.py is just a quick script I wrote to mimic your script
print("Parent: Running the child.")
child = pexpect.spawn("python3 helium-wallet.py")
child.expect("Space separated seed words: ")
child.sendline("carpet again stick economy finish recipe blouse forward program stumble need ginger")
child.expect("Requesting more data: ")

# Now you can use before to see the results of the first input,
# since you moved the cursor forward with pexpect.expect.
print()
print("First input results:")
print("Before:", child.before)
print("Match:", child.match)
print("After:", child.after)
print()

child.sendline("Here's more data!")
output = child.read()
print("Remaining output (including your input):\n", output.decode())

print("Parent: Script complete. Have a nice day.")

子 (helium-wallet.py)：

text = input("Child: Space separated seed words: ")
print("Child: Did something with:", text)
text2 = input("Child: Requesting more data: ")
print("Child: Did something else with:", text2)
print("Child: Script complete. Have a nice day.")

输出：

Parent: Running the child.

First input results:
Before: b'carpet again stick economy finish recipe blouse forward program stumble need ginger\r\nChild: Did something with: carpet again stick economy finish recipe blouse forward program stumble need ginger\r\nChild: '
Match: <re.Match object; span=(204, 226), match=b'Requesting more data: '>
After: b'Requesting more data: '

Remaining output (including your input):
 Here's more data!
Child: Did something else with: Here's more data!
Child: Script complete. Have a nice day.

Parent: Script complete. Have a nice day.

顺便说一句，为了避免输出混乱，我会在每个expect 之后使用一次性child.logfile_read = sys.stdout.buffer 或print(child.before)，但不能同时使用两者。在您的情况下，我建议使用 child.before 仅捕获输出。

祝你编码好运！