To install the latest version of a package named SomePackage:

$ pip install SomePackage

To install a specific version of a package:

$ pip install SomePackage==1.0.4

To specify a minimum version to install for a package:

$ pip install SomePackage>=1.0.4

If commands shows permission denied error on Linux/Unix then use sudo with the commands

Install from requirements files

$ pip install -r requirements.txt

Each line of the requirements file indicates something to be installed, and like arguments to pip install, Details on the format of the files are here: Requirements File Format.

After install the package you can check it using freeze command:

$ pip freeze