Find Python scripts which use an old Python shebang

findoldpy.py

#!/usr/bin/env python3
import os
from pathlib import Path
import sys

bad_shebangs = {
    '/usr/bin/python',
    '/usr/bin/env python',
}

def color(s, c):
    if not color.use:
        return s
    return f"\033[{c}m{s}\033[m"
color.use = sys.stdout.isatty()

def red(s):
    return color(s, 31)

def blue(s):
    return color(s, 34)


def process_file(path):
    try:
        f = path.open('rb')
    except OSError:
        return

    with f:
        head = f.readline(80)

    if not (head.startswith(b'#!') and head.endswith(b'\n')):
        return
    shebang = head[2:-1].decode().strip()

    if shebang in bad_shebangs:
        print(f"{blue(path)}: {red(shebang)}")



def process_dir(toppath):
    for dirpath, dirnames, filenames in os.walk(toppath):
        dirpath = Path(dirpath)
        for filename in filenames:
            path = dirpath / filename
            process_file(path)

def parse_args():
    import argparse
    ap = argparse.ArgumentParser()
    ap.add_argument('dir', default='.')
    return ap.parse_args()

def main():
    args = parse_args()
    process_dir(args.dir)

if __name__ == '__main__':
    main()