CentOS 7 中默认安装了 Python，版本比较低（2.7.5），为了使用新版 3.x，需要对旧版本进行升级。由于很多基本的命令、软件包都依赖旧版本，比如：yum。所以，在更新 Python 时，建议不要删除旧版本（新旧版本可以共存）。
一、查看当前Python版本
# python -V
[root@localhost ~]# python -V Python 2.7.5
二、下载新的Python包并安装
进入python官网（https://www.python.org），选择需要的版本。此处选择Python-3.6.3版本
# yum install gcc gcc-c++ -y
Updated: gcc.x86_64 0:4.8.5-36.el7_6.1 gcc-c++.x86_64 0:4.8.5-36.el7_6.1 Dependency Updated: cpp.x86_64 0:4.8.5-36.el7_6.1 gcc-gfortran.x86_64 0:4.8.5-36.el7_6.1 libgcc.x86_64 0:4.8.5-36.el7_6.1 libgfortran.x86_64 0:4.8.5-36.el7_6.1 libgomp.x86_64 0:4.8.5-36.el7_6.1 libquadmath.x86_64 0:4.8.5-36.el7_6.1 libquadmath-devel.x86_64 0:4.8.5-36.el7_6.1 libstdc++.x86_64 0:4.8.5-36.el7_6.1 libstdc++-devel.x86_64 0:4.8.5-36.el7_6.1 Complete!
下载
# wget https://www.python.org/ftp/python/3.6.3/Python-3.6.3.tgz
# wget https://www.python.org/ftp/python/3.7.3/Python-3.7.3.tgz
[root@localhost ~]# wget https://www.python.org/ftp/python/3.6.3/Python-3.6.3.tgz --2019-04-11 23:45:29-- https://www.python.org/ftp/python/3.6.3/Python-3.6.3.tgz Resolving www.python.org (www.python.org)... 151.101.228.223, 2a04:4e42:1a::223 Connecting to www.python.org (www.python.org)|151.101.228.223|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 22673115 (22M) [application/octet-stream] Saving to: ‘Python-3.6.3.tgz’ 100%[===================================================================================================================>] 22,673,115 73.7KB/s in 3m 23s 2019-04-11 23:48:53 (109 KB/s) - ‘Python-3.6.3.tgz’ saved [22673115/22673115] [root@localhost ~]# [root@localhost ~]# ls anaconda-ks.cfg Python-3.6.3.tgz [root@localhost ~]# [root@localhost ~]# du -sh Python-3.6.3.tgz 22M Python-3.6.3.tgz
解压
# tar zxvf Python-3.6.3.tgz
[root@localhost ~]# ls anaconda-ks.cfg Python-3.6.3 Python-3.6.3.tgz [root@localhost ~]#
查看文件内容
[root@localhost ~]# cd Python-3.6.3 [root@localhost Python-3.6.3]# [root@localhost Python-3.6.3]# ls aclocal.m4 config.sub configure.ac Grammar install-sh LICENSE Makefile.pre.in Modules Parser PCbuild pyconfig.h.in README.rst Tools config.guess configure Doc Include Lib Mac Misc Objects PC Programs Python setup.py [root@localhost Python-3.6.3]# [root@localhost Python-3.6.3]# ll total 1036 -rw-r--r--. 1 501 501 13335 Oct 3 2017 aclocal.m4 -rwxr-xr-x. 1 501 501 44259 Oct 3 2017 config.guess -rwxr-xr-x. 1 501 501 36515 Oct 3 2017 config.sub -rwxr-xr-x. 1 501 501 484734 Oct 3 2017 configure -rw-r--r--. 1 501 501 160430 Oct 3 2017 configure.ac drwxr-xr-x. 18 501 501 4096 Oct 3 2017 Doc drwxr-xr-x. 2 501 501 20 Oct 3 2017 Grammar drwxr-xr-x. 2 501 501 4096 Oct 3 2017 Include -rwxr-xr-x. 1 501 501 7122 Oct 3 2017 install-sh drwxr-xr-x. 33 501 501 8192 Oct 3 2017 Lib -rw-r--r--. 1 501 501 12757 Oct 3 2017 LICENSE drwxr-xr-x. 8 501 501 4096 Oct 3 2017 Mac -rw-r--r--. 1 501 501 59746 Oct 3 2017 Makefile.pre.in drwxr-xr-x. 2 501 501 4096 Oct 3 2017 Misc drwxr-xr-x. 13 501 501 4096 Oct 3 2017 Modules drwxr-xr-x. 4 501 501 4096 Oct 3 2017 Objects drwxr-xr-x. 2 501 501 4096 Oct 3 2017 Parser drwxr-xr-x. 6 501 501 4096 Oct 3 2017 PC drwxr-xr-x. 2 501 501 4096 Oct 3 2017 PCbuild drwxr-xr-x. 2 501 501 79 Oct 3 2017 Programs -rw-r--r--. 1 501 501 41453 Oct 3 2017 pyconfig.h.in drwxr-xr-x. 3 501 501 4096 Oct 3 2017 Python -rw-r--r--. 1 501 501 9269 Oct 3 2017 README.rst -rw-r--r--. 1 501 501 101514 Oct 3 2017 setup.py drwxr-xr-x. 23 501 501 4096 Oct 3 2017 Tools
# ./configure
[root@localhost Python-3.6.3]# ./configure ……………… ……………… ………… creating Modules/Setup creating Modules/Setup.local creating Makefile If you want a release build with all stable optimizations active (PGO, etc), please run ./configure --enable-optimizations
编译安装
# make && make install
报了一个错误
zipimport.ZipImportError: can't decompress data; zlib not available make: *** [install] Error 1
验证
[root@localhost ~]# python -V Python 2.7.5 [root@localhost ~]# python3 -V Python 3.6.3
设置3.6.3为默认版本
查看 Python 的路径，在 /usr/bin 下面。可以看到 python 链接的是 python 2.7，所以，执行 python 就相当于执行 python 2.7
# ll /usr/bin/ | grep python
[root@localhost ~]# ll /usr/bin/ | grep python lrwxrwxrwx. 1 root root 7 Mar 16 18:02 python -> python2 lrwxrwxrwx. 1 root root 9 Mar 16 18:02 python2 -> python2.7 -rwxr-xr-x. 1 root root 7136 Nov 20 2015 python2.7 [root@localhost ~]#
将原来 python 的软链接重命名：
# mv /usr/bin/python /usr/bin/python.bak
将 python 链接至 python3：
# ln -s /usr/local/bin/python3 /usr/bin/python
[root@localhost ~]# ll /usr/bin/ | grep python lrwxrwxrwx. 1 root root 7 Mar 16 18:02 python -> python2 lrwxrwxrwx. 1 root root 9 Mar 16 18:02 python2 -> python2.7 -rwxr-xr-x. 1 root root 7136 Nov 20 2015 python2.7 [root@localhost ~]# [root@localhost ~]# mv /usr/bin/python /usr/bin/python.bak [root@localhost ~]# [root@localhost ~]# ll /usr/bin/ | grep python lrwxrwxrwx. 1 root root 9 Mar 16 18:02 python2 -> python2.7 -rwxr-xr-x. 1 root root 7136 Nov 20 2015 python2.7 lrwxrwxrwx. 1 root root 7 Mar 16 18:02 python.bak -> python2 [root@localhost ~]# [root@localhost ~]# ln -s /usr/local/bin/python3 /usr/bin/python [root@localhost ~]# [root@localhost ~]# ll /usr/bin/ | grep python lrwxrwxrwx. 1 root root 22 Apr 12 00:24 python -> /usr/local/bin/python3 lrwxrwxrwx. 1 root root 9 Mar 16 18:02 python2 -> python2.7 -rwxr-xr-x. 1 root root 7136 Nov 20 2015 python2.7 lrwxrwxrwx. 1 root root 7 Mar 16 18:02 python.bak -> python2 [root@localhost ~]#
配置YUM
升级 Python 之后，由于将默认的 python 指向了 python3，yum 不能正常使用，需要编辑 yum 的配置文件，此时：
[root@localhost ~]# yum list File "/usr/bin/yum", line 30 except KeyboardInterrupt, e: ^ SyntaxError: invalid syntax
修改/usr/bin/yum和/usr/libexec/urlgrabber-ext-down，将 #!/usr/bin/python 改为 #!/usr/bin/python2.7，保存退出即可。
# python -V
[root@localhost ~]# python -V Python 3.6.3
参考博客：
https://www.cnblogs.com/lwf-blog/p/8182975.html
https://www.cnblogs.com/fjping0606/p/9156344.html
https://www.cnblogs.com/simuhunluo/p/7704765.html