Can't concat bytes to str

Question

This is proving to be a rough transition over to python. What is going on here?:

f = open( 'myfile', 'a+' )
f.write('test string' + 'n')

key = "pass:hello"
plaintext = subprocess.check_output(['openssl', 'aes-128-cbc', '-d', '-in', test, '-base64', '-pass', key])
print (plaintext)

f.write (plaintext + 'n')
f.close()

The output file looks like:

test string

and then I get this error:

b'decryption successfuln'
Traceback (most recent call last):
  File ".../Project.py", line 36, in <module>
    f.write (plaintext + 'n')
TypeError: can't concat bytes to str

Asked By: AndroidDev

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Source

Answer 1

subprocess.check_output() returns a bytestring.

In Python 3, there’s no implicit conversion between unicode (str) objects and bytes objects. If you know the encoding of the output, you can .decode() it to get a string, or you can turn the n you want to add to bytes with "n".encode('ascii')

Answered By: Wooble

Answer 2

subprocess.check_output() returns bytes.

so you need to convert ‘n’ to bytes as well:

 f.write (plaintext + b'n')

hope this helps

Answered By: HISI

Answer 3

You can convert type of plaintext to string:

f.write(str(plaintext) + 'n')

Answered By: gcs

Answer 4

f.write(plaintext)
f.write("n".encode("utf-8"))

Answered By: Ravi Prakash

Can't concat bytes to str

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