網上搜到的大部分是這個版本

import pip
from subprocess import call

for dist in pip.get_installed_distributions():
    call("pip install --upgrade " + dist.project_name, shell=True)

使用時會提示pip中沒有這個函式get_installed_distributions()

更新如下

#!/usr/bin/env python
# encoding: utf-8

import pip
from subprocess import call
from pip._internal.utils.misc import get_installed_distributions
for dist in get_installed_distributions():
    call("pip install --upgrade " + dist.project_name, shell=True)