ubuntu 更换国内镜像源

/etc/apt/sources.list

操作：

mv /etc/apt/sources.list /etc/apt/sources.list.bak_curday

vim /etc/apt/sources.list

更换成清华源：

复制进去

 1 # deb cdrom:[Ubuntu 20.04 LTS _Focal Fossa_ - Release amd64 (20200423)]/ focal main restricted
 2 
 3 # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
 4 # newer versions of the distribution.
 5 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted
 6 # deb-src http://us.archive.ubuntu.com/ubuntu/ focal main restricted
 7 
 8 ## Major bug fix updates produced after the final release of the
 9 ## distribution.
10 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted
11 # deb-src http://us.archive.ubuntu.com/ubuntu/ focal-updates main restricted
12 
13 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
14 ## team. Also, please note that software in universe WILL NOT receive any
15 ## review or updates from the Ubuntu security team.
16 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal universe
17 # deb-src http://us.archive.ubuntu.com/ubuntu/ focal universe
18 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates universe
19 # deb-src http://us.archive.ubuntu.com/ubuntu/ focal-updates universe
20 
21 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
22 ## team, and may not be under a free licence. Please satisfy yourself as to 
23 ## your rights to use the software. Also, please note that software in 
24 ## multiverse WILL NOT receive any review or updates from the Ubuntu
25 ## security team.
26 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal multiverse
27 # deb-src http://us.archive.ubuntu.com/ubuntu/ focal multiverse
28 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates multiverse
29 # deb-src http://us.archive.ubuntu.com/ubuntu/ focal-updates multiverse
30 
31 ## N.B. software from this repository may not have been tested as
32 ## extensively as that contained in the main release, although it includes
33 ## newer versions of some applications which may provide useful features.
34 ## Also, please note that software in backports WILL NOT receive any review
35 ## or updates from the Ubuntu security team.
36 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
37 # deb-src http://us.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
38 
39 ## Uncomment the following two lines to add software from Canonical's
40 ## 'partner' repository.
41 ## This software is not part of Ubuntu, but is offered by Canonical and the
42 ## respective vendors as a service to Ubuntu users.
43 # deb http://archive.canonical.com/ubuntu focal partner
44 # deb-src http://archive.canonical.com/ubuntu focal partner
45 
46 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted
47 # deb-src http://security.ubuntu.com/ubuntu focal-security main restricted
48 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security universe
49 # deb-src http://security.ubuntu.com/ubuntu focal-security universe
50 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security multiverse
51 # deb-src http://security.ubuntu.com/ubuntu focal-security multiverse
52 
53 # This system was installed using small removable media
54 # (e.g. netinst, live or single CD). The matching "deb cdrom"
55 # entries were disabled at the end of the installation process.
56 # For information about how to configure apt package sources,
57 # see the sources.list(5) manual.