ubuntu 安装 pythonenv

This will get you going with the latest version of pyenv and make it easy to fork and contribute any changes back upstream.

Check out pyenv where you want it installed. A good place to choose is $HOME/.pyenv (but you can install it somewhere else).
```
$ git clone https://github.com/yyuu/pyenv.git ~/.pyenv
```
Define environment variable PYENV_ROOT to point to the path where pyenv repo is cloned and add $PYENV_ROOT/binto your $PATH for access to the pyenv command-line utility.
```
$ echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.bash_profile
$ echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.bash_profile
```
Zsh note: Modify your ~/.zshenv file instead of ~/.bash_profile. Ubuntu note: Modify your ~/.bashrc file instead of ~/.bash_profile.
Add pyenv init to your shell to enable shims and autocompletion. Please make sure eval "$(pyenv init -)" is placed toward the end of the shell configuration file since it manipulates PATH during the initialization.
```
$ echo 'eval "$(pyenv init -)"' >> ~/.bash_profile
```
Zsh note: Modify your ~/.zshenv file instead of ~/.bash_profile. Ubuntu note: Modify your ~/.bashrc file instead of ~/.bash_profile.

General warning: There are some systems where the BASH_ENV variable is configured to point to .bashrc. On such systems you should almost certainly put the abovementioned line eval "$(pyenv init -) into .bash_profile, andnot into .bashrc. Otherwise you may observe strange behaviour, such as pyenv getting into an infinite loop. See #264for details.
Restart your shell so the path changes take effect. You can now begin using pyenv.
```
$ exec $SHELL
```
Install Python versions into $PYENV_ROOT/versions. For example, to download and install Python 2.7.8, run:
```
$ pyenv install 2.7.8
```