python中的sys.stdout.write无法按预期工作

Question

Consider the following code snippet

#!/usr/bin/python3

import sh
import sys

sys.stdout.write("hello")
sh.whoami(_out=sys.stdout.buffer)

I expect the above program to print

hello
username

but instead i get

username
hello

Can anyone please explain me why this is happening? I am using python 3.5.2 on linux mint 18.1

Answer 1

That's output buffering for you. If you did:

sys.stdout.write("hello")
sys.stdout.flush()
sh.whoami(_out=sys.stdout.buffer)

the order would be as you expected.