gyf@gyf-VirtualBox:~$ git clone https://github.com/yyuu/pyenv.git ~/.pyenv
Cloning into '/home/gyf/.pyenv'...
remote: Enumerating objects: 17608, done.
remote: Total 17608 (delta 0), reused 0 (delta 0), pack-reused 17608
Receiving objects: 100% (17608/17608), 3.47 MiB | 15.00 KiB/s, done.
Resolving deltas: 100% (11960/11960), done.
gyf@gyf-VirtualBox:~$ #
gyf@gyf-VirtualBox:~$ sudo echo 'export PYENV_ROOT="$HOME/.pyenv"'>>~/.bash_profile
gyf@gyf-VirtualBox:~$ sudo echo 'export PATH="$PYENV_ROOT/bin:$PATH"'>>~/.bash_profile
gyf@gyf-VirtualBox:~$ sudo echo 'eval "$(pyenv init -)"'>>~/.bash_profile
gyf@gyf-VirtualBox:~$ source ~/.bash_profile
gyf@gyf-VirtualBox:~$ pyenv --help #这句指令可以验证是否安装成功，出现下面的提示就OK了。
Usage: pyenv <command> [<args>]

Some useful pyenv commands are:
   commands    List all available pyenv commands
   exec        Run an executable with the selected Python version
   global      Set or show the global Python version
   help        Display help for a command
   hooks       List hook scripts for a given pyenv command
   init        Configure the shell environment for pyenv
   install     Install a Python version using python-build
   local       Set or show the local application-specific Python version
   prefix      Display prefix for a Python version
   rehash      Rehash pyenv shims (run this after installing executables)
   root        Display the root directory where versions and shims are kept
   shell       Set or show the shell-specific Python version
   shims       List existing pyenv shims
   uninstall   Uninstall a specific Python version
   version     Show the current Python version and its origin
   --version   Display the version of pyenv
   version-file   Detect the file that sets the current pyenv version
   version-name   Show the current Python version
   version-origin   Explain how the current Python version is set
   versions    List all Python versions available to pyenv
   whence      List all Python versions that contain the given executable
   which       Display the full path to an executable

See `pyenv help <command>' for information on a specific command.
For full documentation, see: https://github.com/pyenv/pyenv#readme
gyf@gyf-VirtualBox:~$