Python2和3切换默认

➜ ~ which python
/usr/local/bin/python
➜ ~ python -V
Python 3.5.0
➜ ~ python2 -V
Python 2.7.6
➜ ~ python3 -V
zsh: command not found: python3
➜ ~ which python
/usr/local/bin/python
➜ ~ l /usr/local/bin/python
lrwxrwxrwx. 1 root root 35 Nov 4 2015 /usr/local/bin/python -> /usr/local/Python-3.5.0/bin/python3
➜ ~ cd /usr/local/bin/
➜ which python2
/usr/bin/python2
➜ ls -alch py*
lrwxrwxrwx. 1 root root 35 Nov 4 2015 python -> /usr/local/Python-3.5.0/bin/python3
➜ ln -s /usr/bin/python2 python
ln: creating symbolic link `python': File exists
➜ rm -rf python
➜ ln -s /usr/bin/python2 python
➜ cd
➜ ~ python