使用pyenv实现python多版本共存

背景

如果是Ubuntu等桌面系统，都已经更新到了Python较新的版本。但多数生产环境使用的还是红帽系统。
CentOS7默认还是Python2.7，而开发环境如果是高版本Python就带来了问题。
为了不破坏当前系统使用，甚至以后为了多个Python项目部署（这些项目使用不同Python解释器版本），建议使用多版本工具。也可以考虑容器部署Python应用程序。

pyenv简介

简单的说，pyenv是管理python版本的工具。安装pyenv后，可以管理各种python版本，并且各个版本的环境完全独立，互不干扰。

官网https://github.com/pyenv/pyenv
快捷安装https://github.com/pyenv/pyenv#the-automatic-installer

#!/usr/bin/env bash

set -e
[ -n "$PYENV_DEBUG" ] && set -x

if [ -z "$PYENV_ROOT" ]; then
  PYENV_ROOT="${HOME}/.pyenv"
fi

colorize() {
  if [ -t 1 ]; then printf "e[%sm%se[m" "$1" "$2"
  else echo -n "$2"
  fi
}

# Checks for `.pyenv` file, and suggests to remove it for installing
if [ -d "${PYENV_ROOT}" ]; then
  { echo
    colorize 1 "WARNING"
    echo ": Can not proceed with installation. Kindly remove the '${PYENV_ROOT}' directory first."
    echo
  } >&2
    exit 1
fi

shell="$1"
if [ -z "$shell" ]; then
  shell="$(ps c -p "$PPID" -o 'ucomm=' 2>/dev/null || true)"
  shell="${shell##-}"
  shell="${shell%% *}"
  shell="$(basename "${shell:-$SHELL}")"
fi

failed_checkout() {
  echo "Failed to git clone $1"
  exit -1
}

checkout() {
  [ -d "$2" ] || git clone --depth 1 "$1" "$2" || failed_checkout "$1"
}

if ! command -v git 1>/dev/null 2>&1; then
  echo "pyenv: Git is not installed, can't continue." >&2
  exit 1
fi

if [ -n "${USE_GIT_URI}" ]; then
  GITHUB="git://github.com"
else
  GITHUB="https://github.com"
fi

checkout "${GITHUB}/pyenv/pyenv.git"            "${PYENV_ROOT}"
checkout "${GITHUB}/pyenv/pyenv-doctor.git"     "${PYENV_ROOT}/plugins/pyenv-doctor"
checkout "${GITHUB}/pyenv/pyenv-installer.git"  "${PYENV_ROOT}/plugins/pyenv-installer"
checkout "${GITHUB}/pyenv/pyenv-update.git"     "${PYENV_ROOT}/plugins/pyenv-update"
checkout "${GITHUB}/pyenv/pyenv-virtualenv.git" "${PYENV_ROOT}/plugins/pyenv-virtualenv"
checkout "${GITHUB}/pyenv/pyenv-which-ext.git"  "${PYENV_ROOT}/plugins/pyenv-which-ext"

if ! command -v pyenv 1>/dev/null; then
  { echo
    colorize 1 "WARNING"
    echo ": seems you still have not added 'pyenv' to the load path."
    echo
  } >&2

  case "$shell" in
  bash )
    profile="~/.bashrc"
    ;;
  zsh )
    profile="~/.zshrc"
    ;;
  ksh )
    profile="~/.profile"
    ;;
  fish )
    profile="~/.config/fish/config.fish"
    ;;
  * )
    profile="your profile"
    ;;
  esac

  { echo "# Load pyenv automatically by adding"
    echo "# the following to ${profile}:"
    echo
    case "$shell" in
    fish )
      echo "set -x PATH "${PYENV_ROOT}/bin" $PATH"
      echo 'status --is-interactive; and . (pyenv init -|psub)'
      echo 'status --is-interactive; and . (pyenv virtualenv-init -|psub)'
      ;;
    * )
      echo "export PATH="${PYENV_ROOT}/bin:$PATH""
      echo "eval "$(pyenv init -)""
      echo "eval "$(pyenv virtualenv-init -)""
      ;;
    esac
  } >&2
fi