Ubuntu16.04默認(rèn)安裝了Python2.7和3.5

請(qǐng)注意，系統(tǒng)自帶的python千萬不能卸載！

輸入命令python

按Ctrl+D退出python命令行

輸入命令sudo add-apt-repository ppa:jonathonf/python-3.6

            Reading package lists... Done
E: Problem executing scripts APT::Update::Post-Invoke-Success
'if /usr/bin/test -w /var/cache/app-info -a -e /usr/bin/appstreamcli;
 then appstreamcli refresh > /dev/null;
 fi'
E: Sub-process returned an error code
          

在運(yùn)行sudo apt-get update時(shí)出現(xiàn)如上信息，解決方法如下：

            sudo pkill -KILL appstreamcli
          

            wget -P /tmp https://launchpad.net/ubuntu/+archive/primary/+files/appstream_0.9.4-1ubuntu1_amd64.deb https://launchpad.net/ubuntu/+archive/primary/+files/libappstream3_0.9.4-1ubuntu1_amd64.deb
          

            sudo dpkg -i /tmp/appstream_0.9.4-1ubuntu1_amd64.deb /tmp/libappstream3_0.9.4-1ubuntu1_amd64.deb
          

執(zhí)行完上述命令之后再次運(yùn)行sudo apt-get update就不會(huì)再出現(xiàn)上面的錯(cuò)誤。

按Enter確認(rèn)

輸入命令sudo apt-get update

輸入命令sudo apt-get install python3.6

按Y確認(rèn)

?

調(diào)整Python3的優(yōu)先級(jí)，使得3.6優(yōu)先級(jí)較高

sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.5 1

sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 2

更改默認(rèn)值，python默認(rèn)為Python2，現(xiàn)在修改為Python3

sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 100

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 150

?

此時(shí)再輸入命令python

可以看到此時(shí)已經(jīng)是Python3.6了