Answers for "how to use requirements.txt"

python requirements.txt

pip freeze #view requirements to be created (best done in virtual env)
pip freeze > requirements.txt #create requirements.txt (best done in virtual env)
pip install -r requirements.txt #install requirements.txt (best done in virtual env)

python requirements.txt

pip install -r requirements.txt

how to install requirements.txt

pip3 install -r requirements.txt

how to get requirements .txt

pip freeze > requirements.txt

command to install requirements.txt

$ pip install -r requirements.txt --no-index --find-links file:///tmp/packages