[FIXED] How do you set a string of bytes from an environment variable in Python?

Issue

Say that you have a string of bytes generated via os.urandom(24),

b'\x1b\xba\x94(\xae\xd0\xb2\xa6\xf2f\xf6\x1fI\xed\xbao$\xc6D\x08\xba\x81\x96v'

and you'd like to store that in an environment variable,

export FOO='\x1b\xba\x94(\xae\xd0\xb2\xa6\xf2f\xf6\x1fI\xed\xbao$\xc6D\x08\xba\x81\x96v'

and retrieve the value from within a Python program using os.environ.

foo = os.environ['FOO']

The problem is that, here, foo has the string literal value '\\x1b\\xba\\x94... instead of the byte sequence b'\x1b\xba\x94....

What is the proper export value to use, or means of using os.environ to treat FOO as a string of bytes?

Solution

You can 'unescape' your bytes in Python with:

import os
import sys

if sys.version_info[0] < 3:  # sadly, it's done differently in Python 2.x vs 3.x
    foo = os.environ["FOO"].decode('string_escape')  # since already in bytes...
else:
    foo = bytes(os.environ["FOO"], "utf-8").decode('unicode_escape')

Answered By - zwer

Answer Checked By - Mary Flores (PHPFixing Volunteer)