Get the version of Python by which the file was compiled

compiled_file_python_version.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
A script to get the version of Python by which the file was compiled
"""

from __future__ import print_function

import binascii
import os
import sys
import struct


MAGICS = {
    20121: 'Python 1.5.x',
    50428: 'Python 1.6',
    50823: 'Python 2.0.x',
    60202: 'Python 2.1.x',
    60717: 'Python 2.2',
    62011: 'Python 2.3a0',
    62021: 'Python 2.3a0',
    62041: 'Python 2.4a0',
    62051: 'Python 2.4a3',
    62061: 'Python 2.4b1',
    62071: 'Python 2.5a0',
    62081: 'Python 2.5a0',
    62091: 'Python 2.5a0',
    62092: 'Python 2.5a0',
    62101: 'Python 2.5b3',
    62111: 'Python 2.5b3',
    62121: 'Python 2.5c1',
    62131: 'Python 2.5c2',
    62151: 'Python 2.6a0',
    62161: 'Python 2.6a1',
    62171: 'Python 2.7a0',
    62181: 'Python 2.7a0',
    62191: 'Python 2.7a0',
    62201: 'Python 2.7a0',
    62211: 'Python 2.7a0',
    3000: 'Python 3000',
    3010: 'Python 3000',
    3020: 'Python 3000',
    3030: 'Python 3000',
    3040: 'Python 3000',
    3050: 'Python 3000',
    3060: 'Python 3000',
    3061: 'Python 3000',
    3071: 'Python 3000',
    3081: 'Python 3000',
    3091: 'Python 3000',
    3101: 'Python 3000',
    3103: 'Python 3000',
    3111: 'Python 3.0a4',
    3131: 'Python 3.0b1',
    3141: 'Python 3.1a1',
    3151: 'Python 3.1a1',
    3160: 'Python 3.2a1',
    3170: 'Python 3.2a2',
    3180: 'Python 3.2a3',
    3190: 'Python 3.3a1',
    3200: 'Python 3.3a1',
    3210: 'Python 3.3a1',
    3220: 'Python 3.3a2',
    3230: 'Python 3.3a4',
    3250: 'Python 3.4a1',
    3260: 'Python 3.4a1',
    3270: 'Python 3.4a1',
    3280: 'Python 3.4a1',
    3290: 'Python 3.4a4',
    3300: 'Python 3.4a4',
    3310: 'Python 3.4rc2',
    3320: 'Python 3.5a1',
    3330: 'Python 3.5b1',
    3340: 'Python 3.5b2',
    3350: 'Python 3.5b3',
    3351: 'Python 3.5.2',
    3360: 'Python 3.6a0',
    3361: 'Python 3.6a1',
    3370: 'Python 3.6a2',
    3371: 'Python 3.6a2',
    3372: 'Python 3.6a2',
    3373: 'Python 3.6b1',
    3375: 'Python 3.6b1',
    3376: 'Python 3.6b1',
    3377: 'Python 3.6b1',
    3378: 'Python 3.6b2',
    3379: 'Python 3.6rc1',
    3390: 'Python 3.7a1',
    3391: 'Python 3.7a2',
    3392: 'Python 3.7a4',
    3393: 'Python 3.7b1',
    3394: 'Python 3.7b5',
    3400: 'Python 3.8a1',
    3401: 'Python 3.8a1',
    3410: 'Python 3.8a1',
    3411: 'Python 3.8b2',
    3412: 'Python 3.8b2',
    3413: 'Python 3.8b4',
    3420: 'Python 3.9a0',
    3421: 'Python 3.9a0',
    3422: 'Python 3.9a0',
    3423: 'Python 3.9a2',
    3424: 'Python 3.9a2',
    3425: 'Python 3.9a2',
    3430: 'Python 3.10a1',
    3431: 'Python 3.10a1',
    3432: 'Python 3.10a2',
    3433: 'Python 3.10a2',
    3434: 'Python 3.10a6',
    3435: 'Python 3.10a7',
    3436: 'Python 3.10b1',
    3437: 'Python 3.10b1',
    3438: 'Python 3.10b1',
    3439: 'Python 3.10b1',
    3450: 'Python 3.11a1',
    3451: 'Python 3.11a1',
    3452: 'Python 3.11a1',
    3453: 'Python 3.11a1',
    3454: 'Python 3.11a1',
    3455: 'Python 3.11a1',
    3456: 'Python 3.11a1',
    3457: 'Python 3.11a1',
    3458: 'Python 3.11a1',
    3459: 'Python 3.11a1',
    3460: 'Python 3.11a1',
    3461: 'Python 3.11a1',
    3462: 'Python 3.11a2',
    3463: 'Python 3.11a3',
    3464: 'Python 3.11a3',
    3465: 'Python 3.11a3',
    3466: 'Python 3.11a4',
    3467: 'Python 3.11a4',
    3468: 'Python 3.11a4',
    3469: 'Python 3.11a4',
    3470: 'Python 3.11a4',
    3471: 'Python 3.11a4',
    3472: 'Python 3.11a4',
    3473: 'Python 3.11a4',
    3474: 'Python 3.11a4',
    3475: 'Python 3.11a5',
    3476: 'Python 3.11a5',
    3477: 'Python 3.11a5',
    3478: 'Python 3.11a5',
    3479: 'Python 3.11a5',
    3480: 'Python 3.11a5',
    3481: 'Python 3.11a5',
    3482: 'Python 3.11a5',
    3483: 'Python 3.11a5',
    3484: 'Python 3.11a5',
    3485: 'Python 3.11a5',
    3486: 'Python 3.11a6',
    3487: 'Python 3.11a6',
    3488: 'Python 3.11a6',
    3489: 'Python 3.11a6',
    3490: 'Python 3.11a6',
    3491: 'Python 3.11a6',
    3492: 'Python 3.11a7',
    3493: 'Python 3.11a7',
    3494: 'Python 3.11a7',
    3495: 'Python 3.11b4',
    3500: 'Python 3.12a1',
    3501: 'Python 3.12a1',
    3502: 'Python 3.12a1',
    3503: 'Python 3.12a1',
    3504: 'Python 3.12a1',
    3505: 'Python 3.12a1',
    3506: 'Python 3.12a1',
    3507: 'Python 3.12a1',
    3508: 'Python 3.12a1',
    3509: 'Python 3.12a1',
    3510: 'Python 3.12a2',
    3511: 'Python 3.12a2',
    3512: 'Python 3.12a2',
    3513: 'Python 3.12a4',
    3514: 'Python 3.12a4',
    3515: 'Python 3.12a5',
    3516: 'Python 3.12a5',
    3517: 'Python 3.12a5',
    3518: 'Python 3.12a6',
    3519: 'Python 3.12a6',
    3520: 'Python 3.12a6',
    3521: 'Python 3.12a7',
    3522: 'Python 3.12a7',
    3523: 'Python 3.12a7',
    3524: 'Python 3.12a7',
    3525: 'Python 3.12b1',
    3526: 'Python 3.12b1',
    3527: 'Python 3.12b1',
    3528: 'Python 3.12b1',
    3529: 'Python 3.12b1',
    3530: 'Python 3.12b1',
    3531: 'Python 3.12b1',
    3550: 'Python 3.13a1',
    3551: 'Python 3.13a1',
    3552: 'Python 3.13a1',
    3553: 'Python 3.13a1',
    3554: 'Python 3.13a1',
    3555: 'Python 3.13a1',
    3556: 'Python 3.13a1',
    3557: 'Python 3.13a1',
    3558: 'Python 3.13a1',
    3559: 'Python 3.13a1',
    3560: 'Python 3.13a1',
    3561: 'Python 3.13a1',
    3562: 'Python 3.13a1',
    3563: 'Python 3.13a1',
    3564: 'Python 3.13a1',
    3565: 'Python 3.13a1',
    3566: 'Python 3.13a1',
    3567: 'Python 3.13a1',
    3568: 'Python 3.13a1',
}


def get_compiled_file_python_version(filename):
    """Get the version of Python by which the file was compiled"""
    ext = os.path.splitext(filename)[1]
    if ext not in ['.pyc', '.pyo']:
        print('Please select *.pyc or *.pyo files')
        return ''
    if not os.path.isfile(filename):
        print('File "%s" doesn\'t exist' % filename)
        return ''
    with open(filename, 'rb') as in_file:
        magic = in_file.read(4)
        magic_data = struct.unpack('H2B', magic)
        python_version = MAGICS.get(magic_data[0], '')
        if magic_data[1:] != (13, 10):
            magic_hex = binascii.hexlify(magic).decode()
            print('Wrong magic bytes "%s". Last two bytes must be "0d0a"!' % magic_hex)
            return ''
        if not python_version:
            print('Unknown Python version or wrong magic bytes!')
    return python_version


def main():
    """Main"""
    if len(sys.argv) < 2:
        sys.exit('Usage: %s <file>' % os.path.basename(sys.argv[0]))
    filename = sys.argv[1]
    python_version = get_compiled_file_python_version(filename)
    if python_version:
        print('File "%s" is compiled with: %s' % (filename, python_version))


if __name__ == '__main__':
    main()

Suggested changes (incl. typo fix):
https://gist.githubusercontent.com/helix84/f14b5516ea501ee220013d7a63db560b/raw/2a037242015bcd747f6b8e501d425dfbed2b20d0/compiled_file_python_version.py

Script is updated - added new magics, added @helix84 fixes.