补充前面安装pyenv的缺漏，又一次我在另一台机子上装pyenv，但是python始终下载不下来。后来找了一圈才发现是依赖没有安装，所以在安装pyenv之前最好先安装一下依赖。已知的一些需要预先安装的库包括：
readline readline-devel readline-static
openssl openssl-devel openssl-static
sqlite-devel
bzip2-devel bzip2-libs
sudo apt-get update
sudo apt-get install make build-essential libssl-dev zlib1g-dev
sudo apt-get install libbz2-dev libreadline-dev libsqlite3-dev wget curl
sudo apt-get install llvm libncurses5-dev libncursesw5-dev
