TypeError: a bytes-like object is required, not 'str' when trying to iterate over a list of running process

Question

I am using Python in Windows. I am trying to kill a windows running process if it is already running but i get below error:

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

I import the following modules:

import os
import subprocess
from time import sleep

Then below my code:

s = subprocess.check_output('tasklist', shell=True)
if "myProcess.exe" in s:
    print('myProcess.exe is currently running. Killing...')
    os.system("taskkill /f /im myProcess.exe")
    sleep(0.5)

The error happens just in the conditional when trying to compare if the process myProcess.exe is in the list s.

In which line is the error? Post the full error message including traceback. — kindall, Apr 10 '23 at 13:07
@kindall just in the "if" when trying to compare if the myProcess is in the list (in this case s) — Willy, Apr 10 '23 at 13:11
@Axe319 your solution works so if you post this as answer I will accept it. Thx in advance. — Willy, Apr 10 '23 at 13:17

score 1 · Accepted Answer · answered Apr 10 '23 at 13:22

By default, subprocess.check_output returns a bytes object. The error you are seeing occurs when you check for membership of a string in bytes.

For example:

'foo' in b'bar'

results in:

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

You can fix this in 2 different ways, by passing in text=True to subprocess.check_output or by simply using a bytes object for membership checking.

s = subprocess.check_output('tasklist', shell=True, text=True)

or:

if b"myProcess.exe" in s:
    # do something

TypeError: a bytes-like object is required, not 'str' when trying to iterate over a list of running process

1 Answers1