Ubuntu安裝Python2+Python3

sudo apt-get install python2.7 python2.7-dev
sudo apt-get install python3

命令：

python    默認執行python2
python2  執行python2
python3  執行python3

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參考：

http://www.cnblogs.com/luckyalan/p/6703590.html

https://www.zhihu.com/question/21653286