- 1 VirtualEnv Tutorial Overview
- 2 Install Python
- 3 Install Easy_Install
- 4 Install PIP
- 5 VirtualEnv Tutorial
- 6 VirtualEnvWrapper
- 7 Create First Environment
- 8 Using PIP with VirtualEnvWrapper
- 9 Appendix: Virtualenv & Git
VirtualEnv Tutorial Overview
Virtualenv tutorial. In this tutorial I will show you in easy steps how to install and use VirtualEnv & VirtualEnvWrapper on your CentOS 6.x environment.
[code lang=”bash”]yum install python[/code]
test python by typing: “python” and you should see something similar to:
[code lang=”bash” inline=”yes”]yum install python-setuptools[/code]
METHOD A: RECOMMENDED : Using Easy_Install
[code lang=”bash” inline=”yes”]easy_install install pip[/code]
METHOD B: You also can install PIP using yum but it’s not recommended.
[code lang=”bash” inline=”yes”]yum install python-pip[/code]
Please note that name of the command is pyton-pip under RHEL and friends. I recommend that you add the following alias to your ~/.bashrc file, enter:
[code lang=”bash” inline=”yes”]echo ‘alias pip=”/usr/bin/pip-python”‘ >> $HOME/.bashrc
Reload your startup file (e.g. source .zshrc) and you’re ready to go.
VirtualEnv Tutorial can only start with installation….
The first step on our virtualenv tutorial is to Install VirtualEnv
[code lang=”bash” inline=”yes”]pip install virtualenv
before we’ll continue to VirtualEnvWrapper lets play a liitle with VirtualEnv:
Create new Virtual Environment
the above command will create a new ‘myenv’ directory and will install easy_install and pip to that directory.
Activate your new environment
Before you can install any Python module into your virtual environment you need to activate it using:
you can see now the command display your virtualenv name in left of the bash shell inside brackets (myenv).
pip install django
You can see inside the myenv/lib/python2.6/site-packages you will find the django framework egg.
Use the pip list command to see installed packages:
Requirement file (requirement.txt)
You can create a requirement file which will help you download & install all the necessary libraries when you deploy or git clone your application elsewhere later.
to create a requirements file from a virtualenv setup (freeze):
[code lang=”bash” inline=”yes”]pip freeze -l > requirements.txt
-l = If in a virtualenv that has global access, do not output globally-installed packages.
installing from a requirements file:
[code lang=”bash” inline=”yes”]pip install -r requirements.txt
to leave the virtual environment use the command:
notice that you are not connected to (myenv) anymore.
To delete a virtual environment just delete its folder:
rm -rf myenv
we’ve finished with the virtualenv tutorial basics. so,… you want more?
virtualenvwrapper is a set of extensions to virtualenv. The extensions include wrappers for creating and deleting virtual environments and otherwise managing your development workflow, making it easier to work on more than one project at a time without introducing conflicts in their dependencies.
- 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 (see Per-User Customization).
- Plugin system for more creating sharable extensions (see Extending Virtualenvwrapper).
(Make sure you deactivated from your virtualenv before continue)
[code lang=”bash” inline=”yes”]pip install virtualenvwrapper
Set up virtualenvwrapper
Virtualenvwrapper needs initialize it’s settings to work properly:
mkdir -p $WORKON_HOME
- The default for WORKON_HOME is “.virtualenvs”. if you missing this line it will be set auto to default when running virtualenvwrapper.sh. I’ve changed it so you could see how it impacts.
- The third command creates new files inside your new ~/Envs (WORKON_HOME) folder.
- You will want to add the command to source /usr/local/bin/virtualenvwrapper.sh to your shell startup file (~/bash_profile)
If the file virtualenvwrapper.sh is not there change the path depending on where it was installed by pip. whereis command can help you if you can’t find it:
…and that’s it! Now you’re all set to start using virtual environments!
Create First Environment
To create your first virtual environment type:
[code lang=”bash”]mkvirtualenv myenv[/code]
the command created a new ~/Envs/myenv folder with 4 folders inside (bin, include, lib and lib64 which is actually a symlink)
Note: as in Virtualenv. you can see that after the mkvirtualenv command you’ve entered the virtualenv automatically (myenv).
like in VirtualEnv – to exit virtual environment type:
[code lang=”bash” inline=”yes”]deactivate[/code]
but now to work on your virtual environment again use:
[code lang=”bash” inline=”yes”]workon myenv[/code]
you don’t need to cd into the folder and use the ./bin/activate command anymore. It’s working wherever you are on your filesystem.
The workon command also includes tab completion for the environment names.
Using PIP with VirtualEnvWrapper
as in VirtualEnv – to install packages to local environment use (for Example Django):
[code lang=”bash” inline=”yes”]pip install Django[/code]
We can see the new package with lssitepackages:
you can see the Django is here…
you can also use the requirements.txt file you created earilier here (If you still have it) and use the
[code lang=”bash” inline=”yes”]pip install -r requirements.txt[/code]
command to install all the packages here.
If you want to delete your environment just use:
If you connected to this virtualenv you must deactivate first.
When you type the workon command it invokes customization scripts as an environment is activated or deactivated (see Per-User Customization).
this simple example script from the readthedocs of VirtualEnvWrapper changes the folder for you when you workon:
(env1)$ echo 'cd $VIRTUAL_ENV' >> $WORKON_HOME/postactivate (env1)$ workon env2 (env2)$ pwd /Users/dhellmann/Envs/env2
or why not install something for us when we create a new virtual environment?
$ echo 'pip install sphinx' >> $WORKON_HOME/postmkvirtualenv
If you want your project files to be in other location and your virtualenvs in other you can set the
and use the mkproject command to create both empty folder at your PROJECT_HOME and virtualenv at your WORKON_HOME
This is great feature! you don’t need to see the virtualenv folders at your project folder and you can save your requirment.txt file at the project.
Appendix: Virtualenv & Git
read this great script which helps you activate your virtualenv whenever you enter your git folder.
For starter – you can find here a full python .gitignore for your new project.