python : redirected message order

Question

我可以在命令行中使用“>”字符简单地重定向 Python 脚本输出。但是，如果 Python 脚本具有 subprocess.call()，则会丢失输出行的顺序。

测试.py

import subprocess

print("Message from Python... this should appear at 1st line")
subprocess.call(r"c:\src\python\redirect2\hi.bat")

嗨.bat

@echo off
echo Message from batch file. this should appear at 2nd line.

下面是我期望的消息。

C:\src\python\redirect2>\Python34\python.exe test.py

Message from Python... this should appear at 1st line
Message from batch file. this should appear at 2nd line.

但是，一旦我重定向了它的输出，这些行的顺序就被调换了。

C:\src\python\redirect2>\Python34\python.exe test.py > console.txt

C:\src\python\redirect2>type console.txt
Message from batch file. this should appear at 2nd line.
Message from Python... this should appear at 1st line

有谁知道如何防止这种情况发生？放置 sleep() 似乎没有帮助。我使用的是 Windows 8.1。

Answer 1

您应该改用 subprocess.Popen，这样您就可以捕获输出。

import subprocess

print("Message from Python... this should appear at 1st line")
p = subprocess.Popen("c:\src\python\redirect2\hi.bat", stdout=subprocess.PIPE)
out, err = p.communicate()

print out