机器升级python3

# 装了个34版本
yum install python34
# 装完后可以用whereis命令查看安装位置
whereis python
#python: /usr/bin/python3.4 /usr/bin/python3.4m /usr/bin/python /usr/bin/python2.6 /usr/bin/python2.6-config /usr/lib/python3.4 /usr/lib/python2.6 /usr/lib64/python3.4 /usr/lib64/python2.6 /usr/include/python3.4m /usr/include/python2.6 /opt/hosteye/bin/python2.7 /usr/share/man/man1/python.1.gz
# 更改默认python可执行程序指向位置
mv /usr/bin/python /usr/bin/python.bak
ln -s /usr/bin/python3.4 /usr/bin/python
python --version
# 显示 Python 3.4.10  则更改成功

当前pip还是基于原始默认python版本，yum卸载重装并不能直接匹配到新python版本，需要自己手动操作

# 首先，需要yum安装python对应pip版本
yum install python34-pip
# 同样，找到pip3安装位置
whereis pip
# python: /usr/bin/python3.4 /usr/bin/python3.4m /usr/bin/python /usr/bin/python2.6 /usr/bin/python2.6-config /usr/lib/python3.4 /usr/lib/python2.6 /usr/lib64/python3.4 /usr/lib64/python2.6 /usr/include/python3.4m /usr/include/python2.6 /opt/hosteye/bin/python2.7 /usr/share/man/man1/python.1.gz
# 更改默认可执行程序指向
mv /usr/bin/pip /usr/bin/pip.bak
ln -s /usr/bin/pip3.4 /usr/bin/pip
pip --version
# 显示 pip 7.1.0 from /usr/lib/python3.4/site-packages (python 3.4)

更改成功，可以愉快的pip install了
但是发现现在pip install需要root权限，不知道后面会不会有影响
然后发现我要装的软件要python3.5及以上，不然报错，不明原因
centos6的yum库中只有python3.4，只能自己下

wget https://www.python.org/ftp/python/3.6.5/Python-3.6.5.tgz
tar zxvf Python-3.6.5.tgz
cd Python-3.6.5
./configure --prefix=/usr/local/python3
make && make install
ln -snf /usr/local/python36/bin/python3.6 /usr/bin/python