python 3: TypeError: a bytes-like object is required, not 'str'

[wardancer84]

hey all,

i know this might be a dull question, but i dont get it...

this works in python2

#!/usr/bin/env python

import subprocess

proclist = subprocess.check_output(['ps', 'uaxw']).splitlines()
cfeagent_procs = [proc for proc in proclist if 'cf-agent' in proc]
cfeagent_count = len(cfeagent_procs)
print(cfeagent_count)
if cfeagent_count > 10:
    print("agents high")

Output:
root@aixhemadbprc2: /root # ./process_count.py
145
agents high

but not in python3

Error:
root@aixhemadbprc2: /root # ./process_count.py
Traceback (most recent call last):
  File "./process_count.py", line 6, in <module>
    cfeagent_procs = [proc for proc in proclist if 'cf-agent' in proc]
  File "./process_count.py", line 6, in <listcomp>
    cfeagent_procs = [proc for proc in proclist if 'cf-agent' in proc]
TypeError: a bytes-like object is required, not 'str'

sorry i need a hint...

wbr

chris

Larz60+ write Jul-09-2021, 05:17 PM:
Please post all code, output and errors (it it's entirety) between their respective tags. Refer to BBCode help topic on how to post. Use the "Preview Post" button to make sure the code is presented as you expect before hitting the "Post Reply/Thread" button.
Fixed for you this time. Please use bbcode tags on future posts.

[DeaD_EyE]

subprocess.check_output(['ps', 'uaxw']).splitlines()

Will output raw bytes because the encoding is missing.
This is the default behavior.

subprocess.check_output(['ps', 'uaxw'], encoding="utf8").splitlines()

Will decode as utf8 and return a str.

Docs: https://docs.python.org/3/library/subpro...eck_output

[wardancer84]

thank you!

[deanhystad]

Your code worked in Python 2 because strings were made up of bytes. In Python 3 strings are made up of Unicode characters. This is a good thing, but it does mean that you'll need to encode/decode when working with legacy software that still thinks ASCII is king.