1.輸入 sudo add-apt-repository ppa:jonathonf/python-3.6
ubuntu@VM-0-13-ubuntu:~$ sudo add-apt-repository ppa:jonathonf/python-3.6
A plain backport of *just* Python 3.6. System extensions/Python libraries may or may not work.
Don't remove Python 3.5 from your system - it will break.
More info: https://launchpad.net/~jonathonf/+archive/ubuntu/python-3.6
Press [ENTER] to continue or ctrl-c to cancel adding it
gpg: keyring `/tmp/tmpo9itxaur/secring.gpg' created
gpg: keyring `/tmp/tmpo9itxaur/pubring.gpg' created
gpg: requesting key F06FC659 from hkp server keyserver.ubuntu.com
gpg: /tmp/tmpo9itxaur/trustdb.gpg: trustdb created
gpg: key F06FC659: public key "Launchpad PPA for J Fernyhough" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
OK提示 ok后就沒問題，如果顯示超時就請再一次輸入剛剛那個命令。
2.輸入 sudo apt-get update
就會出現如圖代碼顯示在更新中。
ubuntu@VM-0-13-ubuntu:~$ sudo apt-get update
Hit:1 http://mirrors.tencentyun.com/ubuntu xenial InRelease
Hit:2 http://mirrors.tencentyun.com/ubuntu xenial-security InRelease
Hit:3 http://mirrors.tencentyun.com/ubuntu xenial-updates InRelease
Get:4 http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu xenial InRelease [18.0 kB]
Get:5 http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu xenial/main amd64 Packages [4,760 B]
Get:6 http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu xenial/main i386 Packages [4,748 B]
94% [Waiting for headers] update命令，會訪問源列表里的每個網址，並讀取軟件列表，然后保存在本地電腦。我們在新立得軟件包管理器里看到的軟件列表，都是通過update命令更新的。
upgrade命令，會把本地已安裝的軟件，與剛下載的軟件列表里對應軟件進行對比，如果發現已安裝的軟件版本太低，就會提示你更新。
輸入命令 sudo apt-get install python3.6
安裝python3.6
ubuntu@VM-0-13-ubuntu:~$ sudo apt-get install python3.6
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
libpython3.6-minimal libpython3.6-stdlib python3.6-minimal
Suggested packages:
python3.6-venv python3.6-doc binfmt-support
The following NEW packages will be installed:
libpython3.6-minimal libpython3.6-stdlib python3.6 python3.6-minimal
0 upgraded, 4 newly installed, 0 to remove and 198 not upgraded.
Need to get 4,505 kB of archives.
After this operation, 23.1 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu xenial/main amd64 libpython3.6-minimal amd64 3.6.5-5~16.04.york1 [574 kB]
Get:2 http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu xenial/main amd64 python3.6-minimal amd64 3.6.5-5~16.04.york1 [1,712 kB]
Get:3 http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu xenial/main amd64 libpython3.6-stdlib amd64 3.6.5-5~16.04.york1 [1,989 kB]
Get:4 http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu xenial/main amd64 python3.6 amd64 3.6.5-5~16.04.york1 [230 kB]
Fetched 4,505 kB in 13s (330 kB/s)
Selecting previously unselected package libpython3.6-minimal:amd64.
(Reading database ... 66624 files and directories currently installed.)
Preparing to unpack .../libpython3.6-minimal_3.6.5-5~16.04.york1_amd64.deb ...
Unpacking libpython3.6-minimal:amd64 (3.6.5-5~16.04.york1) ...
Selecting previously unselected package python3.6-minimal.
Preparing to unpack .../python3.6-minimal_3.6.5-5~16.04.york1_amd64.deb ...
Unpacking python3.6-minimal (3.6.5-5~16.04.york1) ...
Selecting previously unselected package libpython3.6-stdlib:amd64.
Preparing to unpack .../libpython3.6-stdlib_3.6.5-5~16.04.york1_amd64.deb ...
Unpacking libpython3.6-stdlib:amd64 (3.6.5-5~16.04.york1) ...
Selecting previously unselected package python3.6.
Preparing to unpack .../python3.6_3.6.5-5~16.04.york1_amd64.deb ...
Unpacking python3.6 (3.6.5-5~16.04.york1) ...
Processing triggers for man-db (2.7.5-1) ...
Processing triggers for mime-support (3.59ubuntu1) ...
Setting up libpython3.6-minimal:amd64 (3.6.5-5~16.04.york1) ...
Setting up python3.6-minimal (3.6.5-5~16.04.york1) ...
Setting up libpython3.6-stdlib:amd64 (3.6.5-5~16.04.york1) ...
Setting up python3.6 (3.6.5-5~16.04.york1) ...
ubuntu@VM-0-13-ubuntu:~$ 這樣就顯示python3.6安裝成功了。
但是還需要設置一下python3之間的優先級和py2和py3的優先級。
輸入 python 你會發現py2還是默認的python
ubuntu@VM-0-13-ubuntu:~$ python
Python 2.7.12 (default, Dec 4 2017, 14:50:18)
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()
ubuntu@VM-0-13-ubuntu:~$ 現在應該更改默認值，python默認為Python2，現在修改為Python3
ubuntu@VM-0-13-ubuntu:~$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 100
update-alternatives: using /usr/bin/python2 to provide /usr/bin/python (python) in auto mode
ubuntu@VM-0-13-ubuntu:~$ sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 150
update-alternatives: using /usr/bin/python3 to provide /usr/bin/python (python) in auto mode現在查看一下python
ubuntu@VM-0-13-ubuntu:~$ python
Python 3.5.2 (default, Nov 23 2017, 16:37:01)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 發現python3.5 優先於python3.6
現在我們需要更改python3.5為3.6
ubuntu@VM-0-13-ubuntu:~$ sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.5 1
update-alternatives: using /usr/bin/python3.5 to provide /usr/bin/python3 (python3) in auto mode
ubuntu@VM-0-13-ubuntu:~$ sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 2
update-alternatives: using /usr/bin/python3.6 to provide /usr/bin/python3 (python3) in auto mode現在查看一下修改成功了沒有。
ubuntu@VM-0-13-ubuntu:~$ python
Python 3.6.5 (default, May 3 2018, 10:08:28)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 你會發現python3.6是默認的python版本了。
補充問題
安裝python3.6后，發現安裝pip出現了一些問題。
輸入命令sudo apt-get install python-pip安裝pip這個問題
因為現在安裝的是python3.6所以應該是sudo apt-get install python3-pip