This document provides a 3 sentence summary of the PIP and Virtualenv wrapper document: PIP is a tool for installing and managing Python packages and works well with Virtualenv, which creates isolated Python environments to avoid conflicts between packages. Virtualenvwrapper is a set of extensions that organize all virtual environments in one place and provide commands to easily switch between environments. The document discusses installing, configuring, and using PIP, Virtualenv, and Virtualenvwrapper on Linux and Windows systems to manage Python packages across different projects.

1. The hitchhicker's guide to PIP
and Virtualenv (wrapper)...
Maybe...

2. Knowing where one's towel is
"Hey, you sass that hoopy Ford Prefect? There's a frood who really
knows where his towel is." (Sass: know, be aware of, meet, have sex
with; hoopy: really together guy; frood: really amazingly together
guy.)

3. Index
PIP virtual
env
r
r appe
l envw
v irtua
mabye...
and e
veryt
hing
:)
wers
ans

4. Prerequisites
It (maybe) works also
in other *nix and
with a little effort on
● Python :) Windows ;)
● linux ( unfortunately or fortunately :P )
● comfort with shell
● patience required
● internet connection ( not now, but we
work on the web, in the coils of the Python! )

5. What is PIP?
- pip installs packages. Python packages. -
pip is a tool for installing and
managing Python packages, such as
those found in the Python Package
Index (PyPI).
It’s a replacement for easy_install.

6. But... what is Easy Install?
Easy Install is a python module
(easy_install) bundled with
setuptools that lets you
automatically download, build, install,
and manage Python packages.

7. So what?
ea
sy
_i
ns
I P ta
P ll

9. PIP installation
Using package manager, the installer or from source
(root)# apt-get install python-pip
# or
(root)# curl http://python-distribute.org/distribute_setup.
py | python
(root)# curl https://raw.github.
com/pypa/pip/master/contrib/get-pip.py | python
# or
$ curl -O http://[...]/pip-1.0.tar.gz
$ tar xvfz pip-x.y.tar.gz ; cd pip-1.0
# or
$ git clone https://github.com/pypa/pip.git ; cd pip
(root)# python setup.py install

10. PIP usage - base options
$ pip install SomePackage
pip install /path/to/SomePackage.1.1.1.tar.gz
pip install http://myrepo.it/SomePakage-1.4.0.zip
pip install -e git+http://github.com/django/django.git#egg=django
pip install -e path/to/SomePackage
pip install django==1.1.1
==, >=, >, <, <=
$ pip install --upgrade package-name
$ pip uninstall package-name another way for
querying installed
packages given from
$ pip search "query" yolk
$ pip freeze > requirements.txt
Django==1.1.2
ipdb==0.2
$ pip install -r requirements.txt ipython==0.10.1
...

11. PIP configuration
- quickest look -
*nix $HOME/.pip/pip.conf [global]
timeout = 60
windows %HOME%pippip.ini [freeze]
timeout = 10
$ export PIP_DEFAULT_TIMEOUT=10 [install]
$ pip install django find-links =
http://mirror.com
Env. variables
override config file
Each command line options have a
PIP_<UPPER_NAME> environment variables
$ pip --default-timeout=60 install django

12. PyPI
- the Python Pakage Index -
PyPI is a repository of software for Python
and currently count 20481 packages.
The PyPI repository provides alternative locations that store the
packages.
[install]
use-mirrors = true
$ pip --use-mirrors ... mirrors =
$ export PIP_USE_MIRRORS=true http://d.pypi.python.org
http://b.pypi.python.org
You can create your own mirror, following the PEP 381 or using a tool
such as pep381client

13. Want to know more?
Read the docs!
( Luke! :D )
PIP
http://www.pip-installer.org/en/latest/index.html

14. WHY virtual environments?
● Isolation - Python packages and even version live
in their own 'planet' :)
● Permissions - No sudoers, the environment is
mine!!!
● Organization - each project can maintain its own
requirements file of Python packages.
● No-Globalization - don't require installing stuff
globally on the system.

15. PIP + virtualenv
● it's not recommended install packages
globally, but you can :)
● pip works fine with virtualenv!
● used in conjunction to isolate your
installation
Well... step forward: setup and play with
virtual environments!

16. What is virtualenv?
Is a tool to create isolated Python
environments.
Every virtualenv has pip installed in
it automatically (also easy_install)
under bin directory.
Does not require root access or
modify your system.

17. Installation
Using package manager, pip, the installer or using single file
(root)# apt-get install python-virtualenv
# or
(root)# pip install virtualenv
# or
$ curl -O
https://raw.github.com/pypa/virtualenv/master/virtualenv.py

18. Basic Usage
$ virtualenv ENV
This creates a folder ENV in the $PWD
You'll find python packages on ENV/lib/pythonX.X/site-packages
Interesting options!
$ virtualenv --no-site-packages --python=PYTHON_EXE ENV
Doesn't inherit global site-packages and use a different Python interpreter

19. Activate and Using ENV
$ cd ENV ; . bin/activate
(ENV) $ pip install django
Downloading/unpacking django
Downloading Django-1.4.tar.gz (7.6Mb): 5.2Mb downloaded
...
Also virtualenv has a config file
and its looks like pip.conf

20. Extending virtualenv
# django-day.py
import virtualenv, textwrap
output = virtualenv.create_bootstrap_script(textwrap.
dedent())"""
def after_install(options, home_dir):
subprocess.call([join(home_dir, 'bin', 'pip'),
'install',
'django'])
"""
f = open('django-bootstrap.py', 'w').write(output)
extend_parser(optparse_parser):
# add or remove option The script created is an
adjust_options(options, args):
# change options or args
extension to virtualenv
after_install(options, home_dir): and inherit all its options!
# after install run this

22. virtualenvwrapper
by Doug Hellmann
is a set of extensions to Ian Bicking’s
virtualenv tool for creating isolated
Python development environments.
Features, taken verbatim from website:
● Organizes all of your virtual environments in one place.
● Wrappers for managing your virtual environments (create, delete, copy).
● Use a single command to switch between environments.
● Tab completion for commands that take a virtual environment as argument.
● User-configurable hooks for all operations.
● Plugin system for more creating sharable extensions. Your homework ;)

23. Installation
(root)# pip install virtualenvwrapper
$ cd ~
$ mkdir ~/.virtualenvs
Include environment vars needed into ~/.bashrc
export WORKON_HOME=$HOME/.virtualenvs
source /usr/local/bin/virtualenvwrapper.sh
export PIP_VIRTUALENV_BASE=$WORKON_HOME
export PIP_RESPECT_VIRTUALENV=true
A little tips: add to ~/.virtualenvs/postactivate
export PYTHONPATH=$PYTHONPATH:$VIRTUAL_ENV

24. Basic Commands
A brief introducion to manage virtual enviroment
$ mkvirtualenv --no-site-packages --python=PYTHON_EXE ENV
# same as virtualenv!
$ workon ENV (ENV) $ cdvirtualenv
# set virtualenv environment # go to home environment
(ENV) $
(ENV) $ deactivate
# deactivate current environment
$ rmvirtualenv ENV
# remove selected environment

25. More Commands :)
(ENV) $ lssitepackages
# list packages on current environment
(ENV) $ cdsitepackages
# go to site-packages directory
(ENV) $ add2virtualenv directory...
# adds the specified directories to the Python path
(ENV) $ toggleglobalsitepackages
# enable/disable global site-packages
Much more commands & options at
http://www.doughellmann.com/docs/virtualenvwrapper/command_ref.html

26. Simple Sample :P
$ mkvirtualenv --no-site-packages djangoday-rulez
(djangoday-rulez) $ deactivate
$ workon djangoday-rulez
(djangoday-rulez) $ cdvirtualenv
(djangoday-rulez) $ pip install django
... do some cool stuff ...
(djangoday-rulez) $ lssitepackages
(djangoday-rulez) $ deactivate
... do other stuff or switch project
... --- ...
... if it's not so cool ;) ...
$ rmvirtualenv djangoday-rulez

27. Tips & Hooks
virtual environment with "requirements.txt" file
$ mkvirtualenv --no-site-packages
--python=PYTHON_EXE -r django-requirements.txt
$ mkvirtualenv --no-site-packages
-r other-requirements.txt
Under ~/.virtualenvs you'll find the hook scripts that running pre/post
create, activate environments.
postmkvirtualenv
Hooks are simply plain-text files with shell commands. prermvirtualenv
You can customize them to change their behavior when an postrmvirtualenv
postactivate
event occurs. predeactivate
postdeactivate
See extending virtualenv-wrapper: http://bit.ly/IMP0vh

28. Not entirely unlike...
virtualenv virtualenvwrapper
http://bit.ly/141dCr
http://bit.ly/jbFVCe

29. which python ?
Latest stable
2.4.6, 2.5.6,
2.6.8, 2.7.3
Images comes from
Wikipedia

31. pythonbrew !
pythonbrew is a program to automate the
building and installation of Python in the
users $HOME.

32. Installation
Recommended way
$ curl -kL http://xrl.us/pythonbrewinstall | bash
Add the following line into ~/.bashrc
[[ -s $HOME/.pythonbrew/etc/bashrc ]] && source $HOME/.
pythonbrew/etc/bashrc
Last News!!!
The original project seems to be unmantained, but there is
a fork https://github.com/saghul/pythonz
(forked last week... Wait! I have a presentation to do! :D )
Long live pythonz!

33. Usage
Crash course!
$ pythonbrew install VERSION $ pythonbrew off
# install python VERSION # turn off pythonbrew
$ pythonbrew list -k $ pythonbrew use VERSION
# list available pythons # use specified python
$ pythonbrew list $ pythonbrew uninstall VERSION
# list installed pythons # uninstall python VERSION
$ pythonbrew switch VERSION
# permanently use specified python

34. which python
$ pythonbrew use 2.6.5
$ which python
/home/cstrap/.pythonbrew/pythons/Python-2.5.6/bin/python
$ pythonbrew off
$ which python
/usr/bin/python
Cool! And you can create isolated python environments
(it uses virtualenv) ...

35. Create and use pythonbrew
Always use
the --force,
Luke!
$ pythonbrew install --force 2.5.6
... wait... This could take a while...
$ pythonbrew use 2.5.6
$ pythonbrew venv init
$ pythonbrew venv create djangoday-proj
$ pythonbrew venv list # list all environments
$ pythonbrew venv use djangoday-proj
(djangoday-proj) $ pip install django
... do some cool stuff ...
... if it's not so cool ;) ...
$ pythonbrew venv delete djangoday-proj

36. Mostly Harmles...
● virtualenv & virtualenvwrapper
allow you to create and manage
environments using the system default
Python interpreter
● pythonbrew allow you to install
different Python interpreter, create
and manage virtual environments
...

38. Basic Combo
$ pythonbrew install --force 2.6.7
... wait...
$ mkvirtualenv --no-site-packages
-p $HOME/.pythonbrew/pythons/Python-2.6.7/bin/python
djangoDay
... wait...
(djangoDay) $ cdvirtualenv
(djangoDay) [djangoDay] $ pip install django
... wait...
(djangoDay) $ which python ; python -V
/home/cstrap/.virtualenvs/djangoDay/bin/python
Python 2.6.7
(djangoDay) [djangoDay] $ deactivate
$ which python ; python -V
/usr/bin/python
Python 2.7.2

39. Super Combo
$ pythonbrew install --force 2.7.3 ... wait...
$ pythonbrew install --force 2.5.6 ... wait...
$ pythonbrew use 2.7.3
$ pip install virtualenv && pip install virtualenvwrapper
# configure .bashrc
export WORKON_HOME=$HOME/.virtualenvs
export
VIRTUALENVWRAPPER_PYTHON=$HOME/.pythonbrew/pythons/Python-2.7.3/bin/python
source $HOME/.pythonbrew/pythons/Python-2.7.3/bin/virtualenvwrapper.sh
export PIP_VIRTUALENV_BASE=$WORKON_HOME
$ mkdir ~/.virtualenvs
$ mkvirtualenv --no-site-packages
-p $HOME/.pythonbrew/pythons/Python-2.5.6/bin/python djangoDay
(djangoDay) $ which python ; python -V
/home/cstrap/.virtualenvs/djangoDay/bin/python
Python 2.5.6
(djangoDay) [djangoDay] $ deactivate
$ which python ; python -V
/home/cstrap/.pythonbrew/pythons/Python-2.7.3/bin/python
Python 2.7.3
$ pythonbrew off; python -V
# Your current system version of Python

40. Share and Enjoy! :P

41. lab@strap.it
@cstrap

42. Answers?
Thanks for your patience! ;)