As the mainstream development language , use python More and more programs are being developed . What's convenient is that most linux The system is integrated by default python, Development can start anytime, anywhere . But sometimes it becomes a short board , For example, sometimes we need to develop and debug something that needs to be installed by default python The program in the path , Repeated modification and installation will make the system directory more and more disordered , This is not acceptable to some programmers who are obsessed with cleanliness . There are times when we need to be in different python Development on version , Generally, the system only comes with one or two types python edition , Switching is even more troublesome .
This article will introduce how to use pyenv and virtualenv Build multiple versions on a single machine python Virtual development environment .
First, let's find out pyenv and virtualenv What are they .
pyenv It can help you build multiple versions of python Environmental Science , And provide convenient switching methods .
virtualenv Provides a function , Is to create a directory as a virtual python Environmental Science , In this case , Users can create multiple virtual environments , In every environment python Versions can be different , It can be the same , And the environment is independent of each other .
If the explanation is not very clear , Let's give an example of .
First we can use pyenv Install multiple python edition , For example, it is installed 2.5, 2.6, 3.3 Three versions . The user can switch the current default python edition . But this time , Each version of the environment is still unique , If we want to install some libraries in the environment , It will still cause the environment of this version to be modified . This is the time , If we use virtual env To build a virtual environment , It can completely guarantee the cleanness of the system path . No matter what program you install in the virtual environment , Will not affect the installed version of the system environment .
Said so much , It's better to practice . The example of this article is on a clean Ubuntu On the machine
1. First we install pyenv
Because of my Ubuntu It's clean , So you need to install curl and git
sudo apt-get install curl git-core
Next install pyenv
curl -L https://raw.github.com/yyuu/pyenv-installer/master/bin/pyenv-installer | bash
This order will put pyenv Installed to the current user's ~/.pyenv Under the table of contents .
meanwhile , We also need to save the following code to ~/.bashrc In file ：
export PYENV_ROOT="${HOME}/.pyenv"
if [ -d "${PYENV_ROOT}" ]; then
export PATH="${PYENV_ROOT}/bin:${PATH}"
eval "$(pyenv init -)"
fi
The main purpose of this code is to indicate pyenv The location of , So that you can run it directly on the command line in the future pyenv command . Save in ~/.bashrc In the file is to take effect automatically after each user logs in .
So if you run the command for the first time and don't log off , This paragraph will not take effect , We also need to run the following command to make it effective
source ~/.bashrc
Then you can type... Directly on the command line pyenv 了 .
2. Install some necessary packages
sudo apt-get build-dep python2.7
Install other versions later python You will need these bags when you need them
3. Install a version of python
First of all, we can see which versions of python Can install
pyenv install --list
give the result as follows ：
2.4
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.4.6
2.5
...
Next , As an example, we install two versions (2.7.1 and 3.3.5)
pyenv install 2.7.1
pyenv install 3.3.5
After installation , We can check the installation
pyenv versions
The output is as follows ：
* system (set by /home/tony/.pyenv/version)
2.7.1
3.3.5
In short, we have installed three versions of python
system Represents the... Of the current system python edition
2.7.1 and 3.3.5 We use pyenv Installed
* Represents the current python edition , You can see , We are still using the default system Self contained python edition
4. Switch python Test the version
Now that you have installed two other versions of python, Let's do a test
pyenv global 2.7.1
This command is to change the current python Version switch to 2.7.1
Run again pyenv versions, give the result as follows ：
system
* 2.7.1 (set by /home/tony/.pyenv/version)
3.3.5
You can see the current python The version has been switched to 2.7.1 了 , If you don't feel at ease , Direct operation ‘python’ Command to verify ：
[email protected]:~$ python
Python 2.7.1 (r271:86832, May 9 2014, 01:07:17)
[GCC 4.8.2] on linux3
Type "help", "copyright", "credits" or "license" for more information.
>>>
You can see clearly here , The current version is indeed 2.7.1
Empathy , We can continue to use python global Switch between versions , If you want to switch back to the system version , Please use ：
pyenv global system
If you want to uninstall a version of python, It can be like this ：
pyenv uninstall x.x.x
5. utilize virtualenv Create virtual python Environmental Science
Now we have installed multiple python edition , But that's not enough , Some programmers who are obsessed with cleanliness must have a clean system environment , At this time, we can use virtualenv To create a virtual python Environmental Science
virtualenv Ben is an independent tool , The official website is here ：https://pypi.python.org/pypi/virtualenv
Fortunately, , If you are installing in the way we did before pyenv Of , Then it has helped us plugin In the form of virtualenv, We just need to use it
First let's create one 2.7.1 Virtual environment for
pyenv virtualenv 2.7.1 env271
This command creates a command on this machine called env271 Of python A virtual environment , The real directory for this environment is located in ：~/.pyenv/versions/
Be careful , In the command ‘2.7.1’ It must be installed in the previous steps python edition , Otherwise it will go wrong .
Then we can continue through ‘pyenv versions’ Command to view the current virtual environment , give the result as follows ：
* system (set by /home/tony/.pyenv/version)
2.7.1
3.3.5
env271
Here we can see , In addition to the already installed python edition , We have one more env271 Of python A virtual environment
6. Switch and use the new python A virtual environment
The command to switch to the new virtual environment is
pyenv activate env271
Next, our python The environment has been switched to 2.7.1 It's a virtual environment , function ‘python’ Command authentication
(env271)[email protected]:~$ python
Python 2.7.1 (r271:86832, May 9 2014, 01:07:17)
[GCC 4.8.2] on linux3
Type "help", "copyright", "credits" or "license" for more information.
>>>
You can see , python The version is already 2.7.1, And in a virtual environment （env271)
Basically, you can do whatever you want in this virtual environment :) Don't worry about the system path being messed up any more .
If you want to switch back to the system environment , Run this command
pyenv deactivate
What if you want to delete this virtual environment ？ The answer is simple and crude , Just delete the directory where it is located ：
rm -rf ~/.pyenv/versions/env271/
install virtualenv and virtualenvwrapper $sudo apt-get install python-virtualenv $sudo easy_install virtualenvwrapper The above tools cannot be found after being installed mkvirtualenv command , You need to perform the following environment variable settings 1. Create a directory to store the virtual environment mkdir $HOME/.virtualenvs 2. stay ~/.bashrc China Canada Bank ： export WORKON_HOME=$HOME/.virtualenvs source /usr/local/bin/virtualenvwrapper.sh 3. function : source ~/.bashrc 3. establish python A virtual environment mkvirtualenv [ Virtual environment name ] 4. Switch virtual environment workon [ Virtual environment name ] 5. Exit virtual environment deactivate 6. Delete virtual environment rmvirtualenv [ Virtual environment name ] notes ： The created environment is independent , Mutual interference , There is no need to sudo Permission to use pip To manage packages , If used in a virtual environment sudo The installed packages are in the primary environment Use -p Parameter specifies the virtual environment python Version of $ mkvirtualenv -p python python2_tornado
