What is the official "preferred" way to install pip and virtualenv systemwide?

Question

Is it this, which people seem to recommend most often:

$ sudo apt-get install python-setuptools
$ sudo easy_install pip
$ sudo pip install virtualenv

Or this, which I got from http://www.pip-installer.org/en/latest/installing.html:

$ curl -O https://github.com/pypa/virtualenv/raw/master/virtualenv.py
$ python virtualenv.py my_new_env
$ . my_new_env/bin/activate
(my_new_env)$ pip install ...

Or something entirely different?

Answer 1

If you can install the latest Python (2.7.9 and up) Pip is now bundled with it. See: https://docs.python.org/2.7//installing/index.html
If not :
Update (from the release notes):

Beginning with v1.5.1, pip does not require setuptools prior to running get-pip.py. Additionally, if setuptools (or distribute) is not already installed, get-pip.py will install setuptools for you.

I now run the regular:

curl --silent --show-error --retry 5 https://bootstrap.pypa.io/get-pip.py | sudo python

Here are the official installation instructions: http://pip.readthedocs.org/en/latest/installing.html#install-pip

EDIT 25-Jul-2013:
Changed URL for setuptools install.

EDIT 10-Feb-2014:
Removed setuptools install (thanks @Ciantic)

EDIT 26-Jun-2014:
Updated URL again (thanks @LarsH)

EDIT 1-Mar-2015:
Pip is now bundled with Python