A record related to adding APT repositories and modifying mirror sources

Table of Contents
Add repository
Tools required for installation
First execute the following statement.
apt install software-properties-common
After the installation is complete,
executable files named add-apt-repository
and apt-add-repository
will be added in /usr/bin
,
The latter is a linked file and points to the former,
so either one of the two can be used in actual use.
≻ ls -l /usr/bin | grep repository
-rwxr-xr-x 1 root root 7415 1月 27 06:30 add-apt-repository
lrwxrwxrwx 1 root root 18 1月 27 06:30 apt-add-repository -> add-apt-repository
Add repository
To add Emacs and fish as an example, execute the following statement.
add-apt-repository ppa:kelleyk/emacs
add-apt-repository ppa:fish-shell/release-3
Refresh the software index
apt update
Install the corresponding software
apt install emacs27
apt install fish
Modify APT source to improve download speed
General plan
When the official source cannot be accessed
or the download speed is slow due to geographic or network issues,
the server for apt
command can be modified to another mirror server.
Take the change to Huawei mirror server as an example,
execute the following statement.
cp -a /etc/apt/sources.list /etc/apt/sources.list.bak
sed -i "s@http://.*archive.ubuntu.com@http://repo.huaweicloud.com@g" /etc/apt/sources.list
sed -i "s@http://.*security.ubuntu.com@http://repo.huaweicloud.com@g" /etc/apt/sources.list
apt update
Solution for ARM64
Some APT mirror sources are not updated in time, and the system architecture is not fully supported. For the ARM64 architecture, many APT sources in China's mainland have this problem. For example, When Ubuntu running on a Jetson Nano development board.
After testing, the APT mirror source provided by Huawei supports the ARM64 architecture well. Execute the following statement to change to Huawei source.
cp -a /etc/apt/sources.list /etc/apt/sources.list.bak
wget -O /etc/apt/sources.list https://repo.huaweicloud.com/repository/conf/Ubuntu-Ports-bionic.list
apt update