Output installed packages in requirements format.
packages are listed in a case-insensitive sorted order.
Use the order in the given requirements file and its comments when generating output. This option can be used multiple times.
URL for finding packages, which will be added to the output.
If in a virtualenv that has global access, do not output globally-installed packages.
Only output packages installed in user-site.
Do not skip these packages in the output: pip, setuptools, distribute, wheel