Ubuntu 24.04 apt 更换国内镜像站源

Ubuntu 24.04 LTS 后的source.list
24.04LTS 后，apt源的位置替换到了/etc/apt/sources.list.d/ubuntu.sources中

/etc/apt/sources.list
# Ubuntu sources have moved to the /etc/apt/sources.list.d/ubuntu.sources
# file, which uses the deb822 format. Use deb822-formatted .sources files
# to manage package sources in the /etc/apt/sources.list.d/ directory.
# See the sources.list(5) manual page for details.

同时，格式改变，现在为DEB822格式，详见这里
现在的格式是这样的

/etc/apt/sources.list.d/ubuntu.sources
## /etc/cloud/templates/sources.list.ubuntu.deb822.tmpl
##

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

## Ubuntu distribution repository
##
## The following settings can be adjusted to configure which packages to use from Ubuntu.
## Mirror your choices (except for URIs and Suites) in the security section below to
## ensure timely security updates.
##
## Types: Append deb-src to enable the fetching of source package.
## URIs: A URL to the repository (you may add multiple URLs)
## Suites: The following additional suites can be configured
## <name>-updates - Major bug fix updates produced after the final release of the
## distribution.
## <name>-backports - software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
## Components: Aside from main, the following components can be added to the list
## restricted - Software that may not be under a free license, or protected by patents.
## universe - Community maintained packages.
## Software from this repository is only maintained and supported by Canonical
## for machines with Ubuntu Pro subscriptions. Without Ubuntu Pro, the Ubuntu
## community provides best-effort security maintenance.
## multiverse - Community maintained of restricted. Software from this repository is
## ENTIRELY UNSUPPORTED by the Ubuntu team, and may not be under a free
## licence. Please satisfy yourself as to your rights to use the software.
## Also, please note that software in multiverse WILL NOT receive any
## review or updates from the Ubuntu security team.
##
## See the sources.list(5) manual page for further settings.
Types: deb
URIs: http://archive.ubuntu.com/ubuntu
Suites: noble noble-updates noble-backports
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

## Ubuntu security updates. Aside from URIs and Suites,
## this should mirror your choices in the previous section.
Types: deb
URIs: http://security.ubuntu.com/ubuntu
Suites: noble-security
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

因此，如果要使用国内诸如清华TUNA源，USTC源，也需要使用新格式

具体方法
sources.list.d文件夹中，所有.sources拓展名结尾的文件均会被作为一个可选的源
因此我们将原始文件备份：

sudo mv /etc/apt/sources.list.d/ubuntu.sources /etc/apt/backup-sources.list.d-ubuntu.sources
然后创建一个新的文件，以.sources结尾，例如

sudo vim /etc/apt/sources.list.d/tuna.sources
里面填入

Types: deb
URIs: https://mirrors.tuna.tsinghua.edu.cn/ubuntu/
#如果使用其他镜像站，上面这行可以改成其他镜像站的网址
Suites: noble noble-updates noble-backports
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

Types: deb
URIs: http://security.ubuntu.com/ubuntu
#如果安全更新需要使用镜像站，上面这行也改成 URIs: https://mirrors.tuna.tsinghua.edu.cn/ubuntu/
Suites: noble-security
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

之后运行

$ sudo apt update
$ sudo apt upgrade