SHELL

pip install from requirements.txt

$ pip install -r requirements.txt

pip3 install requirements.txt

pip3 install -r requirements.txt

install requirements.txt in pip command

note: yor should be on the same dir as requirements.txt file 

pip install -r requirements.txt

install requirements.txt python

pip install -r requirements.txt
pip install to-requirements.txt

pip3 install requirements.txt

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