不刪除python 2.x安裝python3.x
CentOS7.2下默認系統自帶python2.X的版本，這個版本被系統很多程序所依賴，所以不建議刪除，如果使用最新的Python3那么我們知道編譯安裝源碼包和系統默認包之間是沒有任何影響的，所以可以安裝python3和python2共存。
先檢查CentOS 7.2自帶python及pip:
如果原來的python2版本下沒有pip工具，可以先安裝Python2版本下的pip工具：
wget https://bootstrap.pypa.io/get-pip.py
python get-pip.py
pip -V
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(未驗證)還有一種安裝pip工具方式：先安裝setup-tools，在安裝pip：
wget https://pypi.python.org/packages/2.7/s/setuptools/setuptools-0.6c11-py2.7.egg --no-check-certificate
chmod +x setuptools-0.6c11-py2.7.egg
sh setuptools-0.6c11-py2.7.egg
再安裝pip
wget https://pypi.python.org/packages/source/p/pip/pip-1.3.1.tar.gz --no-check-certificate
cp pip-1.3.1.tar.gz /usr/src/
tar zxvf pip-1.3.1.tar.gz
cd pip-1.3.1
python setup.py install
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先安裝python 2.7版本對應的ipython,此處用pip工具安裝：
提示錯誤：
安裝對應的包：
yum install python-devel libxslt-devel libffi-devel
再用pip安裝對應的ipython:
python 2.7版本對應的ipython安裝成功：
安裝python 3及對應的ipython
1、安裝依賴包
yum -y groupinstall "Development tools" yum -y install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel
2、下載linux平台的python3.x的安裝包(我下載的是python3.6版本)
[root@localhost ~]# wget https://www.python.org/ftp/python/3.6.4/Python-3.6.4.tgz
3、解壓python3.6安裝包
[root@localhost ~]# tar xf Python-3.6.4.tgz [root@localhost ~]# ll total 22024 -rw-------. 1 root root 1238 Jun 25 10:54 anaconda-ks.cfg drwxr-xr-x. 17 501 501 4096 Mar 21 03:47 Python-3.6.4 -rw-r--r--. 1 root root 22540566 Mar 21 03:47 Python-3.6.4.tgz
4、安裝python3.6，安裝路徑為/usr/local/python3
#配置安裝路徑
[root@localhost]# mkdir /usr/local/python3 [root@localhost Python-3.6.4]# ./configure --prefix=/usr/local/python3 #安裝python3.6 [root@localhost Python-3.6.4]# make && make install
5、原來python2和新的python3
[root@bogon Python-3.6.4]# which python /usr/bin/python
[root@bogon Python-3.6.4]# python -V
Python 2.7.5
[root@bogon Python-3.6.4]# /usr/bin/python -V
Python 2.7.5
[root@bogon Python-3.6.4]# /usr/local/python3/bin/python3
python3 python3.6 python3.6-config python3.6m python3.6m-config python3-config
[root@bogon Python-3.6.4]# /usr/local/python3/bin/python3 -V
Python 3.6.4
6、python3.6已安裝成功，在/usr/local/python3/bin下生成命令python3
[root@localhost ~]# ll /usr/local/python3/bin total 24656 lrwxrwxrwx. 1 root root 8 Jun 25 11:22 2to3 -> 2to3-3.6 -rwxr-xr-x. 1 root root 101 Jun 25 11:22 2to3-3.6 -rwxr-xr-x. 1 root root 242 Jun 25 11:22 easy_install-3.6 lrwxrwxrwx. 1 root root 7 Jun 25 11:22 idle3 -> idle3.6 -rwxr-xr-x. 1 root root 99 Jun 25 11:22 idle3.6 -rwxr-xr-x. 1 root root 214 Jun 25 11:22 pip3 -rwxr-xr-x. 1 root root 214 Jun 25 11:22 pip3.6 lrwxrwxrwx. 1 root root 8 Jun 25 11:22 pydoc3 -> pydoc3.6 -rwxr-xr-x. 1 root root 84 Jun 25 11:22 pydoc3.6 lrwxrwxrwx. 1 root root 9 Jun 25 11:22 python3 -> python3.6 -rwxr-xr-x. 2 root root 12604536 Jun 25 11:21 python3.6 lrwxrwxrwx. 1 root root 17 Jun 25 11:22 python3.6-config -> python3.6m-config -rwxr-xr-x. 2 root root 12604536 Jun 25 11:21 python3.6m -rwxr-xr-x. 1 root root 3097 Jun 25 11:22 python3.6m-config lrwxrwxrwx. 1 root root 16 Jun 25 11:22 python3-config -> python3.6-config lrwxrwxrwx. 1 root root 10 Jun 25 11:22 pyvenv -> pyvenv-3.6 -rwxr-xr-x. 1 root root 441 Jun 25 11:22 pyvenv-3.6
7、對新版的python及對應的pip做軟鏈接
ln -sv /usr/local/python3/bin/python3 /usr/bin/python3 ln -sv /usr/local/python3/bin/pip3 /usr/bin/pip3
[root@localhost ~]# which python3 /usr/bin/python3
[root@localhost Python-3.6.4]# pip3 -V
pip 9.0.1 from /usr/local/python3/lib/python3.6/site-packages (python 3.6)
[root@localhost Python-3.6.4]# python3 -V
Python 3.6.4
8、使用python3命令查看版本
[root@localhost ~]# python3 -V Python 3.6.4 [root@localhost local ~]# python3 Python 3.6.4 (default, Jun 25 2017, 11:20:12) [GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux Type "help", "copyright", "credits" or "license" for more information.
9、修改yum配置文件
因為yum使用python2，因此替換為python3后可能無法正常工作，繼續使用這個python2.7.5
因此修改yum配置文件(vi /usr/bin/yum)。
把文件頭部的#!/usr/bin/python改成#!/usr/bin/python2.7保存退出即可。
10、python3安裝ipython
pip3 install ipython
可以看到pip3安裝的ipython對應的是ipython-6.2.1版本；
查看python3的bin目錄下ipython二進制文件，python3的bin目錄下對應的有ipython和ipython3兩個二進制文件
對python3下的ipython做軟連接：
ln -sv /usr/local/python3/bin/ipython3 /usr/bin/ipython3
至此，python3對應的ipython也安裝好了。
