[root@c6-ansible-20 script]# cat demo02.py 
#! /usr/bin/env python
from __future__ import print_function
import sys


for line in sys.stdin:
 print(line,end="")

cat /etc/passwd|python demo02.py

python demo02.py </etc/passwd

[root@c6-ansible-20 script]# cat demo04.py 
#! /usr/bin/env python
from __future__ import print_function
import fileinput


for line in fileinput.input():
 print(line,end='')

python demo04.py /etc/passwd /etc/group