isolate tmpdir

app.py

#!/usr/bin/python
# coding=utf-8

import os
import tempfile
from subprocess import call

def main():
    os.environ["TMPDIR"] = "/home/far/tmp"
    print(tempfile.gettempdir())
    call(["bash", "script.sh"])

if __name__ == "__main__":
    main()

script.sh

#!/bin/bash

tmp=$(mktemp)
echo $tmp

python app.py

/home/far/tmp
/home/far/tmp/tmp.YdqkpH7thy