【QA】Linux-CentOS-源代码编译安装Python-更改镜像源-创建虚拟环境

文章概述

• Linux系统下进行python开发，若是默认安装的python版本不合适，可以安装新的python版本

• 文章演示的系统：Linux CentOS，除了yum形式安装依赖包部分不同，其他部分皆可借鉴到ubuntu

• 系统默认的python版本暂时不删除

Python源码下载、安装

安装版本：Python 3.8

安装相关依赖

[root@localhost ~]# yum install openssl-devel bzip2-devel expat-devel gdbm-devel readline-devel sqlite-devel psmisc libffi-devel zlib* libffi-devel  -y

安装包下载、解压、编译、安装

根目录下，下载安装包

[root@localhost ~]# cd ~
[root@localhost ~]# wget https://registry.npmmirror.com/-/binary/python/3.8.6/Python-3.8.6.tgz

解压缩，并进入解压后的目录

[root@localhost ~]# tar -xf Python-3.8.6.tgz
[root@localhost ~]# cd Python-3.8.6

配置编译和安装的路径，并进行编译和安装

[root@localhost ~]# ./configure --prefix=/usr/local/python38
[root@localhost ~]# make &&  make install

配置环境变量

理解环境变量

[root@localhost ~]# echo $PATH
~/anaconda3/bin:/usr/local/git/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin

以冒号分割，每个目录都是一个系统变量的存放路径。

若运行一个命令python3.8 test.py：

• 这里面的python3.8，Linux会优先到上述路径中找：按照顺序，依次查找
• 若找到了，就执行该命令；若所有路径都没找到，就报错：说没有该命令
• 若这个命令，在不同的路径中都有，则会按照优先级，执行靠前目录下的那个变量

通过建立软连接，来配置python3.8版本的全局访问

[root@localhost ~]# ln -s /usr/local/python38/bin/python3 /usr/bin/python3.8
[root@localhost ~]# ln -s /usr/local/python38/bin/pip3 /usr/bin/pip3.8

上述建立软连接的方法：将python3这个变量，更改为python3.8，所以后续运行的命令就以python3.8写。pip同理

！！！若建立软连接的时候显示软连接已经存在，有可能是系统默认存在python版本，且已经在/usr/bin目录下创建了同名软连接，操作如下：

• 查询软连接来源，可以发现这个软连接不是我们安装的python目录

root@ubuntu:~# readlink -f /usr/bin/python3.8
/usr/bin/python3.8

• 删除已有软连接，并替换为我们的：

root@ubuntu:~# rm -f /usr/bin/python3.8
[root@localhost ~]# ln -s /usr/local/python38/bin/python3 /usr/bin/python3.8

• pip3.8软连接的检查，同上

镜像源替换

安装成功后，执行命令可能会报错：

root@ubuntu:/usr/bin# python3.8 -m pip install --upgrade pip
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/pip/
Could not fetch URL https://pypi.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.")) - skipping
Requirement already up-to-date: pip in /usr/local/python38/lib/python3.8/site-packages (20.2.1)
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Could not fetch URL https://pypi.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.")) - skipping

通过配置镜像源，可以加速下载，避免出错：

• 查询是否有如下目录：有的话直接进入，没有的话创建一个

root@ubuntu:~# cd ~/.pip
-bash: cd: /root/.pip: No such file or directory
root@ubuntu:~# mkdir ~/.pip

• 打开pip.conf配置文件，并写入内容

root@ubuntu:~# cd ~/.pip
root@ubuntu:~/.pip# vim pip.conf

[global]
index-url = http://mirrors.aliyun.com/pypi/simple/
[install]
trusted-host = mirrors.aliyun.com

• 更新pip，成功

python3.8 -m pip install --upgrade pip

虚拟环境配置

virtualenv + virtualenvwrapper

更新pip、setuptools，安装pbr

[root@localhost ~]# python3.8 -m pip install --upgrade pip
[root@localhost ~]# python3.8 -m pip install --upgrade setuptools
[root@localhost ~]# pip3.8 install pbr

安装虚拟环境（第三方库）

[root@localhost ~]# pip3.8 install virtualenv
[root@localhost ~]# pip3.8 install virtualenvwrapper

配置系统变量

[root@localhost ~]# ln -s /usr/local/python38/bin/virtualenv /usr/bin/virtualenv

可以在任何目录，通过virtualenv xxx来管理虚拟环境了

配置虚拟环境

进入文件

[root@localhost ~]# vim ~/.bash_profile

文件末尾填入如下内容

• 第一行命令：创建的虚拟环境如果不特意指定版本，默认就是3.8版本。这个路径，就是上述创建软连接时候的路径（也可以不一样，只要是一个真实存在的就可以）
• 第二行命令：还不知道啥用，先配置上

VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3.8
source /usr/local/python38/bin/virtualenvwrapper.sh

更新配置文件，使配置立刻生效

source ~/.bash_profile

理解profile、bashrc、bash_profile【额外】

文章链接：https://zhuanlan.zhihu.com/p/405174594