Centos 安装 python3.x 为默认

当前初始环境
centos7安装python3有两种方式：
- YUM安装
- 源码安装

正文

CentOS 7 中默认安装了 Python，但是版本是2.x的，由于2020年python2.x将停止更新，因此需要将版本升级至3.x。但由于python2.x是系统集成的，很多命令都是要基于python2.x，比如：yum。因此在更新 Python 时，建议新旧版本共存。

当前初始环境

 # 该系统为最小化安装
[root@TestServer ~]# cat /etc/redhat-release 
CentOS Linux release 7.9.2009 (Core)
[root@TestServer ~]# uname -r
3.10.0-1160.el7.x86_64
 
[root@TestServer ~]# python
Python 2.7.5 (default, Oct 14 2020, 14:45:30) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-44)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 
[root@TestServer ~]# python -V
Python 2.7.5
[root@TestServer ~]# whereis python
python: /usr/bin/python /usr/bin/python2.7 /usr/lib/python2.7 /usr/lib64/python2.7 /etc/python /usr/include/python2.7 /usr/share/man/man1/python.1.gz

centos7安装python3有两种方式：

yum安装，简单方便，但是版本受限
源码安装，较yum安装复杂一点，可安装官方任意版本

YUM安装

自带Python版本：2.7.5
安装Python版本：3.6.8

 # 安装epel源，python3在默认的源中是没有的
[root@TestServer ~]# yum install epel-release -y
# 查看python3版本，根据查到python3的版本来安装，随着python版本更新，epel源中的版本也可能会出现更高版本的python
[root@TestServer ~]# yum search python3        //看到目前有python3.4，python3.6两个版本可以安装
[root@TestServer ~]# yum install python36 -y
# 检查安装结果
[root@TestServer ~]# rpm -qa | grep python3
python3-pip-9.0.3-8.el7.noarch
python3-libs-3.6.8-18.el7.x86_64
python3-setuptools-39.2.0-10.el7.noarch
python3-3.6.8-18.el7.x86_64
[root@TestServer ~]# rpm -ql python3-3.6.8-18.el7.x86_64
/usr/bin/pydoc3
/usr/bin/pydoc3.6
/usr/bin/python3
/usr/bin/python3.6
/usr/bin/python3.6m
/usr/bin/pyvenv
/usr/bin/pyvenv-3.6
/usr/share/doc/python3-3.6.8
/usr/share/doc/python3-3.6.8/README.rst
/usr/share/licenses/python3-3.6.8
/usr/share/licenses/python3-3.6.8/LICENSE
/usr/share/man/man1/python3.1.gz
/usr/share/man/man1/python3.6.1.gz
 
# 设置默认python版本为python-3.6.8
[root@TestServer ~]# mv /usr/bin/python /usr/bin/python_bak
[root@TestServer ~]# ln -s /usr/bin/python3 /usr/bin/python
[root@TestServer ~]# ls -l /usr/bin/python*
lrwxrwxrwx  1 root root    16 Apr 24 11:57 /usr/bin/python -> /usr/bin/python3
lrwxrwxrwx. 1 root root     9 Oct  8  2022 /usr/bin/python2 -> python2.7
-rwxr-xr-x. 1 root root  7144 Oct 14  2020 /usr/bin/python2.7
lrwxrwxrwx  1 root root     9 Apr 24 11:30 /usr/bin/python3 -> python3.6
-rwxr-xr-x  2 root root 11328 Nov 17  2020 /usr/bin/python3.6
-rwxr-xr-x  2 root root 11328 Nov 17  2020 /usr/bin/python3.6m
lrwxrwxrwx. 1 root root     7 Oct  8  2022 /usr/bin/python_bak -> python2
 
[root@TestServer ~]# python -V
Python 3.6.8
[root@TestServer ~]# python2 -V
Python 2.7.5
[root@TestServer ~]# python3 -V
Python 3.6.8
 
# ========== 无法使用yum =============
[root@TestServer ~]# yum install net-tools -y
  File "/usr/bin/yum", line 30
    except KeyboardInterrupt, e:
                            ^
SyntaxError: invalid syntax
 
# 解决方法，仅修改以下两文件的第一行
[root@TestServer ~]# vim /usr/bin/yum
#!/usr/bin/python  修改为---> #!/usr/bin/python2
 
[root@TestServer ~]# vim /usr/libexec/urlgrabber-ext-down
#!/usr/bin/python  修改为---> #!/usr/bin/python2

另外，系统默认的python2.7是没有pip工具的，需要的话，同样安装pip工具。
pip工具也是分python2和python3的，可以共存，下载的包不能共享，即使用pip3下载的包只能在python3中使用，无法在python2.7中使用。

 [root@TestServer ~]# yum install python2-pip -y
 
[root@TestServer ~]# mv /usr/bin/pip /usr/bin/pip_bak
[root@TestServer ~]# ln -s /usr/bin/pip3 /usr/bin/pip
[root@TestServer ~]# ls -l /usr/bin/pip*
lrwxrwxrwx 1 root root  13 Apr 24 15:20 /usr/bin/pip -> /usr/bin/pip3
-rwxr-xr-x 1 root root 284 Sep  3  2020 /usr/bin/pip2
-rwxr-xr-x 1 root root 288 Sep  3  2020 /usr/bin/pip2.7
-rwxr-xr-x 1 root root 407 Oct 14  2020 /usr/bin/pip3
lrwxrwxrwx 1 root root   9 Apr 24 14:46 /usr/bin/pip-3 -> ./pip-3.6
lrwxrwxrwx 1 root root   8 Apr 24 14:46 /usr/bin/pip-3.6 -> ./pip3.6
-rwxr-xr-x 1 root root 407 Oct 14  2020 /usr/bin/pip3.6
-rwxr-xr-x 1 root root 282 Sep  3  2020 /usr/bin/pip_bak
 
[root@TestServer ~]# pip -V
pip 9.0.3 from /usr/lib/python3.6/site-packages (python 3.6)
[root@TestServer ~]# pip2 -V
pip 8.1.2 from /usr/lib/python2.7/site-packages (python 2.7)
[root@TestServer ~]# pip3 -V
pip 9.0.3 from /usr/lib/python3.6/site-packages (python 3.6)

注意：Python 2.7.9 + 或 Python 3.4+ 以上版本都自带 pip 工具。

源码安装

Centos7系统恢复快照至初始环境。

自带Python版本：2.7.5
安装Python版本：3.9.16

首先去python官网下载页面，下载需要的稳定版python3源码

【https://www.python.org/downloads/source/】
【https://www.python.org/ftp/python/】

目前最新版本为：Python 3.11.3

 # 安装依赖
[root@TestServer ~]# yum install -y openssl-devel bzip2-devel expat-devel gdbm-devel readline-devel sqlite-devel libffi-devel wget gcc make
# 下载需求版本
[root@TestServer ~]# wget https://www.python.org/ftp/python/3.9.16/Python-3.9.16.tgz
[root@TestServer ~]# tar -xf Python-3.9.16.tgz
[root@TestServer ~]# cd Python-3.9.16
[root@TestServer Python-3.9.16]# ./configure --prefix=/usr/local/python3.9
[root@TestServer Python-3.9.16]# make && make install
 
# 设置默认python版本为 python-3.9.16
[root@TestServer ~]# mv /usr/bin/python /usr/bin/python_bak
[root@TestServer ~]# ln -s /usr/local/src/python3.9/bin/python3 /usr/bin/python
[root@TestServer ~]# ln -s /usr/local/src/python3.9/bin/python3 /usr/bin/python3
[root@TestServer ~]# ls -l /usr/bin/python*
lrwxrwxrwx  1 root root   36 Apr 24 16:23 /usr/bin/python -> /usr/local/src/python3.9/bin/python3
lrwxrwxrwx. 1 root root    9 Oct  8  2022 /usr/bin/python2 -> python2.7
-rwxr-xr-x. 1 root root 7144 Oct 14  2020 /usr/bin/python2.7
lrwxrwxrwx  1 root root   36 Apr 24 16:23 /usr/bin/python3 -> /usr/local/src/python3.9/bin/python3
lrwxrwxrwx. 1 root root    7 Oct  8  2022 /usr/bin/python_bak -> python2
 
[root@TestServer ~]# python -V
Python 3.9.16
[root@TestServer ~]# python2 -V
Python 2.7.5
[root@TestServer ~]# python3 -V
Python 3.9.16
 
# ========== 无法使用yum =============
[root@TestServer ~]# yum list
  File "/usr/bin/yum", line 30
    except KeyboardInterrupt, e:
                            ^
SyntaxError: invalid syntax
 
# 解决方法，仅修改以下两文件的第一行
[root@TestServer ~]# vim /usr/bin/yum
#!/usr/bin/python  修改为---> #!/usr/bin/python2
 
[root@TestServer ~]# vim /usr/libexec/urlgrabber-ext-down
#!/usr/bin/python  修改为---> #!/usr/bin/python2

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原文地址：https://www.cnblogs.com/zhangwencheng/p/17347288.html

	# 该系统为最小化安装
	[root@TestServer ~]# cat /etc/redhat-release
	CentOS Linux release 7.9.2009 (Core)
	[root@TestServer ~]# uname -r
	3.10.0-1160.el7.x86_64

	[root@TestServer ~]# python
	Python 2.7.5 (default, Oct 14 2020, 14:45:30)
	[GCC 4.8.5 20150623 (Red Hat 4.8.5-44)] on linux2
	Type "help", "copyright", "credits" or "license" for more information.
	>>>
	[root@TestServer ~]# python -V
	Python 2.7.5
	[root@TestServer ~]# whereis python
	python: /usr/bin/python /usr/bin/python2.7 /usr/lib/python2.7 /usr/lib64/python2.7 /etc/python /usr/include/python2.7 /usr/share/man/man1/python.1.gz

	# 安装epel源，python3在默认的源中是没有的
	[root@TestServer ~]# yum install epel-release -y
	# 查看python3版本，根据查到python3的版本来安装，随着python版本更新，epel源中的版本也可能会出现更高版本的python
	[root@TestServer ~]# yum search python3 //看到目前有python3.4，python3.6两个版本可以安装
	[root@TestServer ~]# yum install python36 -y
	# 检查安装结果
	[root@TestServer ~]# rpm -qa \| grep python3
	python3-pip-9.0.3-8.el7.noarch
	python3-libs-3.6.8-18.el7.x86_64
	python3-setuptools-39.2.0-10.el7.noarch
	python3-3.6.8-18.el7.x86_64
	[root@TestServer ~]# rpm -ql python3-3.6.8-18.el7.x86_64
	/usr/bin/pydoc3
	/usr/bin/pydoc3.6
	/usr/bin/python3
	/usr/bin/python3.6
	/usr/bin/python3.6m
	/usr/bin/pyvenv
	/usr/bin/pyvenv-3.6
	/usr/share/doc/python3-3.6.8
	/usr/share/doc/python3-3.6.8/README.rst
	/usr/share/licenses/python3-3.6.8
	/usr/share/licenses/python3-3.6.8/LICENSE
	/usr/share/man/man1/python3.1.gz
	/usr/share/man/man1/python3.6.1.gz

	# 设置默认python版本为python-3.6.8
	[root@TestServer ~]# mv /usr/bin/python /usr/bin/python_bak
	[root@TestServer ~]# ln -s /usr/bin/python3 /usr/bin/python
	[root@TestServer ~]# ls -l /usr/bin/python*
	lrwxrwxrwx 1 root root 16 Apr 24 11:57 /usr/bin/python -> /usr/bin/python3
	lrwxrwxrwx. 1 root root 9 Oct 8 2022 /usr/bin/python2 -> python2.7
	-rwxr-xr-x. 1 root root 7144 Oct 14 2020 /usr/bin/python2.7
	lrwxrwxrwx 1 root root 9 Apr 24 11:30 /usr/bin/python3 -> python3.6
	-rwxr-xr-x 2 root root 11328 Nov 17 2020 /usr/bin/python3.6
	-rwxr-xr-x 2 root root 11328 Nov 17 2020 /usr/bin/python3.6m
	lrwxrwxrwx. 1 root root 7 Oct 8 2022 /usr/bin/python_bak -> python2

	[root@TestServer ~]# python -V
	Python 3.6.8
	[root@TestServer ~]# python2 -V
	Python 2.7.5
	[root@TestServer ~]# python3 -V
	Python 3.6.8

	# ========== 无法使用yum =============
	[root@TestServer ~]# yum install net-tools -y
	File "/usr/bin/yum", line 30
	except KeyboardInterrupt, e:
	^
	SyntaxError: invalid syntax

	# 解决方法，仅修改以下两文件的第一行
	[root@TestServer ~]# vim /usr/bin/yum
	#!/usr/bin/python 修改为---> #!/usr/bin/python2

	[root@TestServer ~]# vim /usr/libexec/urlgrabber-ext-down
	#!/usr/bin/python 修改为---> #!/usr/bin/python2

	[root@TestServer ~]# yum install python2-pip -y

	[root@TestServer ~]# mv /usr/bin/pip /usr/bin/pip_bak
	[root@TestServer ~]# ln -s /usr/bin/pip3 /usr/bin/pip
	[root@TestServer ~]# ls -l /usr/bin/pip*
	lrwxrwxrwx 1 root root 13 Apr 24 15:20 /usr/bin/pip -> /usr/bin/pip3
	-rwxr-xr-x 1 root root 284 Sep 3 2020 /usr/bin/pip2
	-rwxr-xr-x 1 root root 288 Sep 3 2020 /usr/bin/pip2.7
	-rwxr-xr-x 1 root root 407 Oct 14 2020 /usr/bin/pip3
	lrwxrwxrwx 1 root root 9 Apr 24 14:46 /usr/bin/pip-3 -> ./pip-3.6
	lrwxrwxrwx 1 root root 8 Apr 24 14:46 /usr/bin/pip-3.6 -> ./pip3.6
	-rwxr-xr-x 1 root root 407 Oct 14 2020 /usr/bin/pip3.6
	-rwxr-xr-x 1 root root 282 Sep 3 2020 /usr/bin/pip_bak

	[root@TestServer ~]# pip -V
	pip 9.0.3 from /usr/lib/python3.6/site-packages (python 3.6)
	[root@TestServer ~]# pip2 -V
	pip 8.1.2 from /usr/lib/python2.7/site-packages (python 2.7)
	[root@TestServer ~]# pip3 -V
	pip 9.0.3 from /usr/lib/python3.6/site-packages (python 3.6)

	# 安装依赖
	[root@TestServer ~]# yum install -y openssl-devel bzip2-devel expat-devel gdbm-devel readline-devel sqlite-devel libffi-devel wget gcc make
	# 下载需求版本
	[root@TestServer ~]# wget https://www.python.org/ftp/python/3.9.16/Python-3.9.16.tgz
	[root@TestServer ~]# tar -xf Python-3.9.16.tgz
	[root@TestServer ~]# cd Python-3.9.16
	[root@TestServer Python-3.9.16]# ./configure --prefix=/usr/local/python3.9
	[root@TestServer Python-3.9.16]# make && make install

	# 设置默认python版本为 python-3.9.16
	[root@TestServer ~]# mv /usr/bin/python /usr/bin/python_bak
	[root@TestServer ~]# ln -s /usr/local/src/python3.9/bin/python3 /usr/bin/python
	[root@TestServer ~]# ln -s /usr/local/src/python3.9/bin/python3 /usr/bin/python3
	[root@TestServer ~]# ls -l /usr/bin/python*
	lrwxrwxrwx 1 root root 36 Apr 24 16:23 /usr/bin/python -> /usr/local/src/python3.9/bin/python3
	lrwxrwxrwx. 1 root root 9 Oct 8 2022 /usr/bin/python2 -> python2.7
	-rwxr-xr-x. 1 root root 7144 Oct 14 2020 /usr/bin/python2.7
	lrwxrwxrwx 1 root root 36 Apr 24 16:23 /usr/bin/python3 -> /usr/local/src/python3.9/bin/python3
	lrwxrwxrwx. 1 root root 7 Oct 8 2022 /usr/bin/python_bak -> python2

	[root@TestServer ~]# python -V
	Python 3.9.16
	[root@TestServer ~]# python2 -V
	Python 2.7.5
	[root@TestServer ~]# python3 -V
	Python 3.9.16

	# ========== 无法使用yum =============
	[root@TestServer ~]# yum list
	File "/usr/bin/yum", line 30
	except KeyboardInterrupt, e:
	^
	SyntaxError: invalid syntax

	# 解决方法，仅修改以下两文件的第一行
	[root@TestServer ~]# vim /usr/bin/yum
	#!/usr/bin/python 修改为---> #!/usr/bin/python2

	[root@TestServer ~]# vim /usr/libexec/urlgrabber-ext-down
	#!/usr/bin/python 修改为---> #!/usr/bin/python2