Python Flask：Hello world

adamhuan@leviathan ~ % sudo pip install --upgrade pip
WARNING: The directory '/Users/adamhuan/Library/Caches/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you should use sudo's -H flag.
Looking in indexes: https://mirrors.aliyun.com/pypi/simple/
Requirement already satisfied: pip in Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages (22.2.2)
Collecting pip
  Downloading https://mirrors.aliyun.com/pypi/packages/08/e3/57d4c24a050aa0bcca46b2920bff40847db79535dc78141eb83581a52eb8/pip-23.1.2-py3-none-any.whl (2.1 MB)
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Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 22.2.2
    Uninstalling pip-22.2.2:
      Successfully uninstalled pip-22.2.2
Successfully installed pip-23.1.2
WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv
adamhuan@leviathan ~ % 


adamhuan@leviathan ~ % sudo pip install flask
Password:
WARNING: The directory '/Users/adamhuan/Library/Caches/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you should use sudo's -H flag.
Looking in indexes: https://mirrors.aliyun.com/pypi/simple/
Collecting flask
  Downloading https://mirrors.aliyun.com/pypi/packages/9f/27/fc83394961f97e74c860d05f9bc848af00259b8c84ca021ab31250b9915e/Flask-2.3.1-py3-none-any.whl (96 kB)
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Collecting blinker>=1.6.2
  Downloading https://mirrors.aliyun.com/pypi/packages/0d/f1/5f39e771cd730d347539bb74c6d496737b9d5f0a53bc9fdbf3e170f1ee48/blinker-1.6.2-py3-none-any.whl (13 kB)
Requirement already satisfied: Jinja2>=3.1.2 in Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages (from flask) (3.1.2)
Collecting Werkzeug>=2.3.0
  Downloading https://mirrors.aliyun.com/pypi/packages/80/b2/7b7467a8c766121d061bae61f378fc62726c49511c5c8ae435a76d146361/Werkzeug-2.3.2-py3-none-any.whl (242 kB)
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Collecting click>=8.1.3
  Downloading https://mirrors.aliyun.com/pypi/packages/c2/f1/df59e28c642d583f7dacffb1e0965d0e00b218e0186d7858ac5233dce840/click-8.1.3-py3-none-any.whl (96 kB)
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Collecting itsdangerous>=2.1.2
  Downloading https://mirrors.aliyun.com/pypi/packages/68/5f/447e04e828f47465eeab35b5d408b7ebaaaee207f48b7136c5a7267a30ae/itsdangerous-2.1.2-py3-none-any.whl (15 kB)
Requirement already satisfied: MarkupSafe>=2.0 in Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages (from Jinja2>=3.1.2->flask) (2.1.1)
Installing collected packages: Werkzeug, itsdangerous, click, blinker, flask
Successfully installed Werkzeug-2.3.2 blinker-1.6.2 click-8.1.3 flask-2.3.1 itsdangerous-2.1.2
WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv


[notice] A new release of pip available: 22.2.2 -> 23.1.2
[notice] To update, run: pip install --upgrade pip
adamhuan@leviathan ~ % 


adamhuan@leviathan ~ % pip list
Package              Version
-------------------- -----------
appdirs              1.4.4
Appium-Python-Client 2.7.1
APScheduler          3.7.0
aria2p               0.11.2
async-generator      1.10
async-timeout        4.0.2
attrs                22.1.0
Automat              20.2.0
beautifulsoup4       4.11.1
blinker              1.6.2
certifi              2022.9.24
cffi                 1.15.1
charset-normalizer   2.1.1
click                8.1.3
constantly           15.1.0
coverage             6.5.0
cryptography         38.0.1
cssselect            1.1.0
Deprecated           1.2.13
distlib              0.3.6
Django               2.2.28
django-apscheduler   0.6.0
django-cors-headers  3.7.0
djangorestframework  3.13.1
exceptiongroup       1.0.4
filelock             3.8.0
fire                 0.4.0
flake8               5.0.4
Flask                2.3.1
furl                 2.1.3
gerapy               0.9.11
gevent               21.12.0
greenlet             1.1.3
h11                  0.14.0
hyperlink            21.0.0
idna                 3.4
importlib-metadata   5.0.0
incremental          21.3.0
iniconfig            1.1.1
itemadapter          0.7.0
itemloaders          1.0.6
itsdangerous         2.1.2
Jinja2               3.1.2
jmespath             1.0.1
loguru               0.6.0
lxml                 4.9.1
MarkupSafe           2.1.1
mccabe               0.7.0
mock                 4.0.3
orderedmultidict     1.0.1
outcome              1.2.0
packaging            21.3
parsel               1.6.0
pip                  23.1.2
platformdirs         2.5.2
pluggy               1.0.0
Protego              0.2.1
py                   1.11.0
pyasn1               0.4.8
pyasn1-modules       0.2.8
pycodestyle          2.9.1
pycparser            2.21
PyDispatcher         2.0.6
pyee                 8.2.2
pyflakes             2.5.0
pymongo              4.2.0
PyMySQL              1.0.2
pyOpenSSL            22.1.0
pyparsing            3.0.9
pyppeteer            1.0.2
pyquery              1.4.3
PySocks              1.7.1
pytest               7.1.3
pytest-cov           4.0.0
python-scrapyd-api   2.1.2
pytz                 2022.4
queuelib             1.6.2
redis                4.3.4
requests             2.28.1
requests-file        1.5.1
Scrapy               2.6.3
scrapy-redis         0.7.3
scrapy-splash        0.8.0
selenium             4.6.1
service-identity     21.1.0
setuptools           58.1.0
six                  1.16.0
sniffio              1.3.0
sortedcontainers     2.4.0
soupsieve            2.3.2.post1
sqlparse             0.4.3
superset             0.30.1
termcolor            2.1.1
tldextract           3.4.0
toml                 0.10.2
tomli                2.0.1
tox                  3.26.0
tqdm                 4.64.1
trio                 0.22.0
trio-websocket       0.9.2
Twisted              22.8.0
typing_extensions    4.4.0
tzlocal              2.1
urllib3              1.26.12
virtualenv           20.16.5
w3lib                2.0.1
websocket            0.2.1
websocket-client     1.4.2
websockets           10.3
Werkzeug             2.3.2
wrapt                1.14.1
wsproto              1.2.0
zipp                 3.8.1
zope.event           4.5.0
zope.interface       5.4.0
adamhuan@leviathan ~ %


adamhuan@leviathan ~ % pip list | grep "Flask" 
Flask                2.3.1
adamhuan@leviathan ~ %

adamhuan@leviathan ~ % cd flask_project 
adamhuan@leviathan flask_project % 
adamhuan@leviathan flask_project % mkdir hello_world
adamhuan@leviathan flask_project % cd hello_world 
adamhuan@leviathan hello_world % 
adamhuan@leviathan hello_world % touch app.py
adamhuan@leviathan hello_world % 
adamhuan@leviathan hello_world % pwd
/Users/adamhuan/flask_project/hello_world
adamhuan@leviathan hello_world % 
adamhuan@leviathan hello_world % ls -ltr
total 0
-rw-r--r--  1 adamhuan  staff  0  4 29 22:16 app.py
adamhuan@leviathan hello_world % 

adamhuan@leviathan hello_world % vi app.py 
adamhuan@leviathan hello_world % 
adamhuan@leviathan hello_world % cat app.py 
from flask import Flask


app = Flask(__name__)




@app.route('/')
def hello_world():  # put application's code here
    return 'Hello World!'




if __name__ == '__main__':
    app.run()


adamhuan@leviathan hello_world % 

adamhuan@leviathan hello_world % python3 app.py 
 * Serving Flask app 'app'
 * Debug mode: off
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
 * Running on http://127.0.0.1:5000
Press CTRL+C to quit