centos7升级Python2.x到3.x

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.

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 :4.8.-.el7_6.                                               gcc-c++.x86_64 :4.8.-.el7_6.                                              

Dependency Updated:
  cpp.x86_64 :4.8.-.el7_6.                         gcc-gfortran.x86_64 :4.8.-.el7_6.           libgcc.x86_64 :4.8.-.el7_6.
  libgfortran.x86_64 :4.8.-.el7_6.                 libgomp.x86_64 :4.8.-.el7_6.                libquadmath.x86_64 :4.8.-.el7_6.
  libquadmath-devel.x86_64 :4.8.-.el7_6.           libstdc++.x86_64 :4.8.-.el7_6.              libstdc++-devel.x86_64 :4.8.-.el7_6.          

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
---- ::--  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::
Connecting to www.python.org (www.python.org)|151.101.228.223|:... connected.
HTTP request sent, awaiting response...  OK
Length:  (22M) [application/octet-stream]
Saving to: ‘Python-3.6..tgz’

%[===================================================================================================================>] ,,  .7KB/s   in 3m 23s 

-- :: ( KB/s) - ‘Python-3.6..tgz’ saved [/]

[root@localhost ~]#
[root@localhost ~]# ls
anaconda-ks.cfg  Python-3.6..tgz
[root@localhost ~]#
[root@localhost ~]# du -sh Python-3.6..tgz
22M     Python-3.6..tgz

解压

# tar zxvf Python-3.6.3.tgz

[root@localhost ~]# ls
anaconda-ks.cfg  Python-3.6.  Python-3.6..tgz
[root@localhost ~]# 

查看文件内容

[root@localhost ~]# cd Python-3.6.
[root@localhost Python-3.6.]#
[root@localhost Python-3.6.]# 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.]#
[root@localhost Python-3.6.]# ll
total
-rw-r--r--.       Oct     aclocal.m4
-rwxr-xr-x.       Oct     config.guess
-rwxr-xr-x.       Oct     config.sub
-rwxr-xr-x.      Oct     configure
-rw-r--r--.      Oct     configure.ac
drwxr-xr-x.       Oct     Doc
drwxr-xr-x.          Oct     Grammar
drwxr-xr-x.        Oct     Include
-rwxr-xr-x.        Oct     install-sh
drwxr-xr-x.       Oct     Lib
-rw-r--r--.       Oct     LICENSE
drwxr-xr-x.        Oct     Mac
-rw-r--r--.       Oct     Makefile.pre.in
drwxr-xr-x.        Oct     Misc
drwxr-xr-x.       Oct     Modules
drwxr-xr-x.        Oct     Objects
drwxr-xr-x.        Oct     Parser
drwxr-xr-x.        Oct     PC
drwxr-xr-x.        Oct     PCbuild
drwxr-xr-x.          Oct     Programs
-rw-r--r--.       Oct     pyconfig.h.in
drwxr-xr-x.        Oct     Python
-rw-r--r--.        Oct     README.rst
-rw-r--r--.      Oct     setup.py
drwxr-xr-x.       Oct     Tools

# ./configure

[root@localhost Python-3.6.]# ./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 

验证

[root@localhost ~]# python -V
Python 2.7.
[root@localhost ~]# python3 -V
Python 3.6.

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.    root root           Mar  : python -> python2
lrwxrwxrwx.    root root           Mar  : python2 -> python2.
-rwxr-xr-x.    root root        Nov    python2.
[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.    root root           Mar  : python -> python2
lrwxrwxrwx.    root root           Mar  : python2 -> python2.
-rwxr-xr-x.    root root        Nov    python2.
[root@localhost ~]#
[root@localhost ~]# mv /usr/bin/python /usr/bin/python.bak
[root@localhost ~]#
[root@localhost ~]# ll /usr/bin/ | grep python
lrwxrwxrwx.    root root           Mar  : python2 -> python2.
-rwxr-xr-x.    root root        Nov    python2.
lrwxrwxrwx.    root root           Mar  : 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.    root root          Apr  : python -> /usr/local/bin/python3
lrwxrwxrwx.    root root           Mar  : python2 -> python2.
-rwxr-xr-x.    root root        Nov    python2.
lrwxrwxrwx.    root root           Mar  : 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
    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.

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