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Requirements file

# Output the list of installed packages
pip list
# Output the list of dependancy versions
pip freeze
# Export it to a text file
pip freeze > requirements.txt
# Install by reading from requirements.txt
pip install -r requirements.txt

Install specific version of package (you can use * global sign)

python3 -m pip install "package==1.4"
pip install "package==1.4"
pip install "package==1*" (will install any version starting with 1)

Install greater than or equal to version 1 and less than version 2:

python3 -m pip install "SomeProject>=1,<2"

All INFO at official page: https://packaging.python.org/tutorials/installing-packages/

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