Windows环境Python进程查杀报错：TypeError: a bytes-like object is required, not 'str'

错误原因 #

subprocess.check_output()默认返回字节流（bytes类型），你用字符串"myProcess.exe"直接和字节流做成员判断，类型不匹配导致报错：

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

三种可行解决方案 #

方案1：指定encoding参数直接返回字符串 #

Windows命令行默认编码为GBK，给check_output添加encoding='gbk'参数，让返回结果直接是字符串：

import os
import subprocess
from time import sleep

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

方案2：将判断字符串转为字节流 #

保持check_output的返回值为bytes，把判断用的字符串转为字节流（加b前缀）：

import os
import subprocess
from time import sleep

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

方案3：使用universal_newlines=True参数（兼容旧版Python） #

该参数会让check_output返回字符串，效果和指定encoding类似，适合Python 3.7及之前版本：

import os
import subprocess
from time import sleep

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

内容的提问来源于stack exchange，提问作者Willy