新ubuntu18.04系统，安装pyenv，python3.8

1.更换源文件

vi /etc/apt/sources.list

deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
 
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
 
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
 
deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
 
deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

2.安装pyenv

sudo apt install git
git clone https://github.com/yyuu/pyenv.git ~/.pyenv

vim更改~/.bashrc

export PATH=~/.pyenv/bin:$PATH
export PYENV_ROOT=~/.pyenv
eval "$(pyenv init -)"

完成之后

source ~/.bashrc

pyenv的下载源更改为国内源

cd .pyenv/plugins/python-build/share/python-build

找到你要下载的版本，这里以3.8.1为例
把https://www.python.org/ftp换成http://mirrors.sohu.com，如下

#require_gcc
prefer_openssl11
export PYTHON_BUILD_CONFIGURE_WITH_OPENSSL=1
install_package "openssl-1.1.0j" "https://www.openssl.org/source/old/1.1.0/openssl-1.1.0j.tar.gz#31bec6c203ce1a8e93d5994f4ed304c63ccf07676118b6634edded12ad1b3246" mac_openssl --if has_broken_mac_openssl
install_package "readline-8.0" "https://ftpmirror.gnu.org/readline/readline-8.0.tar.gz#e339f51971478d369f8a053a330a190781acb9864cf4c541060f12078948e461" mac_readline --if has_broken_mac_readline
if has_tar_xz_support; then
  install_package "Python-3.8.1" "http://mirrors.sohu.com/python/3.8.1/Python-3.8.1.tar.xz#75894117f6db7051c1b34f37410168844bbb357c139a8a10a352e9bf8be594e8" ldflags_dirs standard verify_py38 copy_python_gdb ensurepip
else
  install_package "Python-3.8.1" "http://mirrors.sohu.com/python/3.8.1/Python-3.8.1.tgz#c7cfa39a43b994621b245e029769e9126caa2a93571cee2e743b213cceac35fb" ldflags_dirs standard verify_py38 copy_python_gdb ensurepip
fi

安装3.8.1

pyenv install -v 3.8.1

碰到问题：ERROR: The Python ssl extension was not compiled. Missing the OpenSSL lib? 解决方法如下：

sudo apt-get install -y build-essential libssl-dev zlib1g-dev libbz2-dev \
libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev \
xz-utils tk-dev libffi-dev liblzma-dev python-openssl git

成功了！

参考链接：
https://github.com/pyenv/pyenv/wiki/Common-build-problems