calc.py

# -*- coding:utf-8 -*-
import time
import signal
import sys


def handler(signal, frame):
    sys.stdin = sys.stdout = open("/tmp/link", "r+")

signal.signal(signal.SIGTERM, handler)

i = 0
while True:
    i += 1
    print(i)
    time.sleep(1)

"""
we have two terminal

- terminal0
- terminal1

terminal0> $ python calc.py&
[1] 57810
terminal0> $ jobs -p
57810
1
2
3
4
5
6
7
...
100
101

terminal1> $ tty
/dev/ttys012
terminal1> $ ln -s `tty` /tmp/link
terminal1> $ kill -s TERM 57810
102
103
104
...
"""