pip freeze
Description
Output installed packages in requirements format.
packages are listed in a case-insensitive sorted order.
Examples
Generate output suitable for a requirements file.
python -m pip freeze
docutils==0.11
Jinja2==2.7.2
MarkupSafe==0.19
Pygments==1.6
Sphinx==1.2.2
Generate a requirements file and then install from it in another environment.
env1/bin/python -m pip freeze > requirements.txt
env2/bin/python -m pip install -r requirements.txt