7 centos 更改默认Python哦 centos8默认python版本

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mob64ca1403c772 2023-08-16 11:36:36

文章标签 python 开发语言后端 pyenv linux 文章分类 Python 后端开发

Python的版本问题

目前企业中使用的Python主要版本是2.x和3.x。
官方已经停止2.x的维护，最后一个版本是2.7，但仍有部分项目使用
3.x各版本间同样有互不兼容的问题。

CentOS 6 默认Python版本为2.6.6
CentOS 7 默认Python版本为2.7
CentOS 8 默认Python版本为3.6.8
Ubuntu18 默认Python版本为2.7和3.6
Ubuntu20 默认Python版本为3.8

CentOS 8 上，Python 默认没有被安装。yum使用了一个内部的 Python 二进制文件和库文件。

Python2和3的区别

在类和库方面有代差，3.x新增了很多库，2.x没有，2.x有一些库被3.x抛弃了
在异常处理方面有语法的改变
3.x版本以后统一使用Unicode解决了2.x版本乱码的问题
3.x版本中input函数合二为一，不再使用raw_input
3.x版本中print变成函数式，以前是语句式
3.x版本中/为自然除，整除用//

pyenv实现python多版本共存方案

在不适用docker或者kmv等虚拟技术的环境中，为解决pythony多版本安装，我们通常使用github上的pythonenv进行虚拟环境部署。

官网： https://github.com/pyenv/pyenv

CentOS8部署pyenv

安装git

yum install git curl -y

安装依赖

yum install -y gcc make patch gdbm-devel openssl-devel readline-devel zlib-devel bzip2-devel
...
Upgraded:
  cpp-8.5.0-4.el8_5.x86_64                  gcc-8.5.0-4.el8_5.x86_64                 
  gcc-c++-8.5.0-4.el8_5.x86_64              libgcc-8.5.0-4.el8_5.x86_64              
  libgomp-8.5.0-4.el8_5.x86_64              libstdc++-8.5.0-4.el8_5.x86_64           
  libstdc++-devel-8.5.0-4.el8_5.x86_64      ncurses-6.1-9.20180224.el8.x86_64        
  ncurses-base-6.1-9.20180224.el8.noarch    ncurses-libs-6.1-9.20180224.el8.x86_64   
Installed:
  bzip2-devel-1.0.6-26.el8.x86_64            gdbm-devel-1:1.18-1.el8.x86_64         
  ncurses-c++-libs-6.1-9.20180224.el8.x86_64 ncurses-devel-6.1-9.20180224.el8.x86_64
  patch-2.7.6-11.el8.x86_64                  readline-devel-7.0-10.el8.x86_64

创建开发环境普通用户

useradd python;echo -e 'python\npython' | passwd python

[root@C8-196 ~]# useradd python;echo -e 'python\npython' | passwd python
Changing password for user python.
New password: BAD PASSWORD: The password is shorter than 8 characters
Retype new password: passwd: all authentication tokens updated successfully.
[root@C8-196 ~]# su - python
[python@C8-196 ~]$

查看官方安装脚本找出需要git下来的东西哦

由于你懂的原因估计curl不行github
curl -L https://github.com/pyenv/pyenv-installer/raw/master/bin/pyenv-installer | bash
我们就不到长城非好汉的方式把脚本拷贝下来再执行

checkout "${GITHUB}/pyenv/pyenv.git"            "${PYENV_ROOT}"  ## 这个是最基础的，必须得有的
checkout "${GITHUB}/pyenv/pyenv-doctor.git"     "${PYENV_ROOT}/plugins/pyenv-doctor" ## 这个是用于doctor得，可以没有的
checkout "${GITHUB}/pyenv/pyenv-installer.git"  "${PYENV_ROOT}/plugins/pyenv-installer" ## 这个是安装器，必须的把自己下载下来
checkout "${GITHUB}/pyenv/pyenv-update.git"     "${PYENV_ROOT}/plugins/pyenv-update" ## 这个update也得有啊！
checkout "${GITHUB}/pyenv/pyenv-virtualenv.git" "${PYENV_ROOT}/plugins/pyenv-virtualenv" ## 创建虚拟环境，必须要有
checkout "${GITHUB}/pyenv/pyenv-which-ext.git"  "${PYENV_ROOT}/plugins/pyenv-which-ext" ## 为pyenv提供'push'和'pop'

使用git命令一点一点都给下载下来吧

git路径为https的时候有可能报错，还是使用git://才好

git clone  git://github.com/pyenv/pyenv.git  ~/.pyenv
git clone  git://github.com/pyenv/pyenv-installer.git ~/.pyenv/plugins/pyenv-installer
git clone  git://github.com/pyenv/pyenv-update.git ~/.pyenv/plugins/pyenv-update
git clone  git://github.com/pyenv/pyenv-virtualenv.git ~/.pyenv/plugins/pyenv-virtualenv
git clone  git://github.com/pyenv/pyenv-which-ext.git ~/.pyenv/plugins/pyenv-which-ext

[python@C8-196 ~]$ tree -L 1 .pyenv/
.pyenv/
├── bin
├── CHANGELOG.md
├── COMMANDS.md
├── completions
├── CONDUCT.md
├── Dockerfile
├── libexec
├── LICENSE
├── Makefile
├── man
├── plugins
├── pyenv.d
├── README.md
├── src
├── terminal_output.png
└── test

8 directories, 8 files
[python@C8-196 ~]$ tree -L 1 .pyenv/plugins/
.pyenv/plugins/
├── pyenv-installer
├── pyenv-update
├── pyenv-virtualenv
├── pyenv-which-ext
└── python-build

5 directories, 0 files

修改系统环境变量

重要的事情说三遍
这里一定要注意呀，开始只在bashrc里修改不好使，要按照官方的修改方式去改才行
这里一定要注意呀，开始只在bashrc里修改不好使，要按照官方的修改方式去改才行
这里一定要注意呀，开始只在bashrc里修改不好使，要按照官方的修改方式去改才行

sed -Ei -e '/^([^#]|$)/ {a \
export PYENV_ROOT="$HOME/.pyenv"
a \
export PATH="$PYENV_ROOT/bin:$PATH"
a \
' -e ':a' -e '$!{n;ba};}' ~/.bash_profile
echo 'eval "$(pyenv init --path)"' >> ~/.bash_profile

echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.profile
echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.profile
echo 'eval "$(pyenv init --path)"' >> ~/.profile

echo 'eval "$(pyenv init -)"' >> ~/.bashrc

设置完就好了

[python@C8-196 ~]$ cd projects/web36
[python@C8-196 web36]$ pyenv versions
  system
  3.10.0
* 3.6.15 (set by /home/python/projects/web36/.python-version)
  3.6.15/envs/py3615
  3.6.15/envs/venv
  3.8.12
  py3615
  venv
[python@C8-196 web36]$ python -V
Python 3.6.15
[python@C8-196 web36]$ pip -V
pip 18.1 from /home/python/.pyenv/versions/3.6.15/lib/python3.6/site-packages/pip (python 3.6)

使用pyenv安装多版本python

查看pyenv支持的可用的python版本

[python@C8-196 ~]$ pyenv install -l | less

我们可以将已下载好的，需要安装部署的python安装包上传至pyenv中的cache目录中
如果没有，可以提前下载好呀

#!/bin/bash
Cache_DIR="~/.pyenv/cache"
[ -p ${Cache_DIR} ] || mkdir -pv ${Cache_DIR}

for PYTHON_RV in {2.7.18,3.5.10,3.6.15,3.7.12,3.8.12,3.9.7,3.10.0};do
    wget https://www.python.org/ftp/python/"${PYTHON_RV}"/Python-"${PYTHON_RV}".tar.xz  -P ~/.pyenv/cache
done

使用pyenv安装多版本python

如果cache目录中已有，则直接编译安装
如果cache目录中没有，会从官网进行下载后再安装，就是慢
查看已有安装包

[python@C8-196 ~]$ cd .pyenv/cache/;ll -h
total 122M
-rw-rw-r-- 1 python python 18M Oct  5 02:34 Python-3.10.0.tar.xz
-rw-rw-r-- 1 python python 24M Oct  5 02:34 Python-3.10.0.tgz
-rw-rw-r-- 1 python python 17M Sep  4 14:21 Python-3.6.15.tar.xz
-rw-rw-r-- 1 python python 22M Sep  4 14:20 Python-3.6.15.tgz
-rw-rw-r-- 1 python python 18M Aug 31 00:55 Python-3.8.12.tar.xz
-rw-rw-r-- 1 python python 24M Aug 31 00:55 Python-3.8.12.tgz

使用pyenv install 安装需要的版本

[python@C8-196 cache]$ pyenv install -vvv 3.8.12
/tmp/python-build.20211209133311.16824 ~/.pyenv/cache
/tmp/python-build.20211209133311.16824/Python-3.8.12 /tmp/python-build.20211209133311.16824 ~/.pyenv/cache
Installing Python-3.8.12...
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking for python3.8... no
checking for python3... no
checking for python... no
checking for --enable-universalsdk... no
checking for --with-universal-archs... no
checking MACHDEP... "linux"
...

安装完成后查看支持的版本

[python@C8-196 cache]$ pyenv versions
  3.10.0
  3.6.15
  3.8.12

pyenv设置python版本的三种主要方式

pyenv local ## 对当前目录生效，每个项目一个目录，每个目录设定对应的python版本，实现不同目录，不同版本，互不干扰

[python@C8-196 web36]$ pyenv local --help
Usage: pyenv local <version> <version2> <..>
       pyenv local --unset

Sets the local application-specific Python version(s) by writing the
version name to a file named `.python-version'.

When you run a Python command, pyenv will look for a `.python-version'
file in the current directory and each parent directory. If no such
file is found in the tree, pyenv will use the global Python version
specified with `pyenv global'. A version specified with the
`PYENV_VERSION' environment variable takes precedence over local
and global versions.

<version> can be specified multiple times and should be a version
tag known to pyenv.  The special version string `system' will use
your default system Python.  Run `pyenv versions' for a list of
available Python versions.

Example: To enable the python2.7 and python3.7 shims to find their
         respective executables you could set both versions with:

'pyenv local 3.7.0 2.7.15'

pyenv shell ## 跟当前shell环境有关，临时用一下还行，退出重登后就失效了，不推荐

[python@C8-196 web36]$ pyenv shell --help
Usage: pyenv shell <version>...
       pyenv shell -
       pyenv shell --unset

Sets a shell-specific Python version by setting the `PYENV_VERSION'
environment variable in your shell. This version overrides local
application-specific versions and the global version.

<version> should be a string matching a Python version known to pyenv.
The special version string `system' will use your default system Python.
Run `pyenv versions' for a list of available Python versions.

When `-` is passed instead of the version string, the previously set
version will be restored. With `--unset`, the `PYENV_VERSION`
environment variable gets unset, restoring the environment to the
state before the first `pyenv shell` call.

pyenv globle ## 用户得全局设定，不要破坏,不建议使用，如果是root执行，杀伤力就太大了

[python@C8-196 web36]$ pyenv global --help
Usage: pyenv global <version> <version2> <..>

Sets the global Python version(s). You can override the global version at
any time by setting a directory-specific version with `pyenv local'
or by setting the `PYENV_VERSION' environment variable.

<version> can be specified multiple times and should be a version
tag known to pyenv.  The special version string `system' will use
your default system Python.  Run `pyenv versions' for a list of
available Python versions.

Example: To enable the python2.7 and python3.7 shims to find their
         respective executables you could set both versions with:

'pyenv global 3.7.0 2.7.15'

pyenv实现目录绑定python多版本共存

mkdir -pv ~/projects/{web36,web38,web310}

[python@C8-196 cache]$ mkdir -pv ~/projects/{web36,web38,web310}
mkdir: created directory '/home/python/projects'
mkdir: created directory '/home/python/projects/web36'
mkdir: created directory '/home/python/projects/web38'
mkdir: created directory '/home/python/projects/web310'

[python@C8-196 projects]$ cd web36
[python@C8-196 web36]$ pyenv local 3.6.15
[python@C8-196 web36]$ pyenv version
3.6.15 (set by /home/python/projects/web36/.python-version)
[python@C8-196 web36]$ python -V
Python 3.6.15

pyenv虚拟环境实现目录python多版本共存

大的公用版本环境，如果安装不同库可能会有冲突
为每一个项目都有一个隔离的小环境，需要pyenv配置虚拟环境
创建虚拟版本
pyenv virtualenv <可用版本> <虚拟版本名>
指定项目目录使用虚拟版本
pyenv local <虚拟版本名>

[python@C8-196 web38]$ pyenv virtualenv 3.8.12 py3812a
Looking in links: /tmp/tmp5utow02w
Requirement already satisfied: setuptools in /home/python/.pyenv/versions/3.8.12/envs/py3812a/lib/python3.8/site-packages (56.0.0)
Requirement already satisfied: pip in /home/python/.pyenv/versions/3.8.12/envs/py3812a/lib/python3.8/site-packages (21.1.1)
[python@C8-196 web38]$ pyenv versions
* system (set by /home/python/.pyenv/version)
  3.10.0
  3.6.15
  3.6.15/envs/py3615
  3.6.15/envs/venv
  3.8.12
  3.8.12/envs/py3812a
  py3615
  py3812a
  venv
[python@C8-196 web38]$ mkdir -pv {py3812a,py3812b}
mkdir: created directory 'py3812a'
mkdir: created directory 'py3812b'
[python@C8-196 web38]$ pyenv virtualenv 3.8.12 py3812b
Looking in links: /tmp/tmp_kok0cu4
Requirement already satisfied: setuptools in /home/python/.pyenv/versions/3.8.12/envs/py3812b/lib/python3.8/site-packages (56.0.0)
Requirement already satisfied: pip in /home/python/.pyenv/versions/3.8.12/envs/py3812b/lib/python3.8/site-packages (21.1.1)
[python@C8-196 web38]$ cd py3812a
[python@C8-196 py3812a]$ pyenv local py3812a
(py3812a) [python@C8-196 py3812a]$ python -V
Python 3.8.12
(py3812a) [python@C8-196 py3812a]$ pyenv version
py3812a (set by /home/python/projects/web38/py3812a/.python-version)
(py3812a) [python@C8-196 py3812a]$ cd ../py3812b
[python@C8-196 py3812b]$ pyenv local py3812b
(py3812b) [python@C8-196 py3812b]$ python -V
Python 3.8.12
(py3812b) [python@C8-196 py3812b]$ pyenv version
py3812b (set by /home/python/projects/web38/py3812b/.python-version)

至此，多版本共存Python开发环境已经部署完了
在此至上可以部署ipython和Jupyter配合开发
pip install ipython jupyterjupyter notebook --ip=0.0.0.0

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7 centos 更改默认Python哦 centos8默认python版本

7 centos 更改默认Python哦 centos8默认python版本

Python的版本问题

Python2和3的区别

pyenv实现python多版本共存方案

CentOS8部署pyenv

使用pyenv安装多版本python

pyenv设置python版本的三种主要方式

pyenv实现目录绑定python多版本共存

pyenv虚拟环境实现目录python多版本共存

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