import os
import subprocess

program = 'program'
with open(program, "w") as fp:
    print("#!/usr/bin/env bash", file=fp)
    print('echo "subprocess searchs in the current directory"', file=fp)
    fp.flush()

os.chmod(program, 0o777)

args = [program]
env = dict(os.environ)
env.pop('PATH', None)

print("defpath = %s" % os.path.defpath)
subprocess.run(args, env=env)