使用whereis指令，获取python3的路径
    whereis python3
    提示:
    python3: /usr/bin/python3.8-config /usr/bin/python3 /usr/bin/python3.8 /usr/lib/python3 /usr/lib/python3.9 /usr/lib/python3.8 /etc/python3 /etc/python3.8 /usr/local/lib/python3.8 /usr/include/python3.8 /usr/share/python3

    编辑.bashrc文件
    gedit ~/.bashrc

    alias python=’/usr/bin/python3’
    source ~/.bashrc