我安装的是Ubuntu 20.04.6 LTS的Windows上Linux子系统版本，启动完成后显示：

Welcome to Ubuntu 20.04.6 LTS (GNU/Linux 5.15.90.4-microsoft-standard-WSL2 x86_64)

• Documentation: https://help.ubuntu.com
• Management: https://landscape.canonical.com
• Support: https://ubuntu.com/advantage

System information as of Sun Aug 20 09:42:18 CST 2023

System load: 0.64 Processes: 132
Usage of /: 1.0% of 1006.85GB Users logged in: 0
Memory usage: 9% IPv4 address for eth0: 172...151
Swap usage: 0%

• Strictly confined Kubernetes makes edge and IoT secure. Learn how MicroK8s
  just raised the bar for easy, resilient and secure K8s cluster deployment.

  https://ubuntu.com/engage/secure-kubernetes-at-the-edge

Expanded Security Maintenance for Applications is not enabled.

1 update can be applied immediately.
To see these additional updates run: apt list --upgradable

8 additional security updates can be applied with ESM Apps.
Learn more about enabling ESM Apps service at https://ubuntu.com/esm

This message is shown once a day. To disable it please create the
/home/hann/.hushlogin file.

启动信息告知：有1个升级可以立即更新，另外ESM应用程序有8个额外的安全更新。

更新内容列表：

hann@HannYang:$ apt list --upgradable
Listing... Done
cloud-init/focal-updates 23.2.2-0ubuntu020.04.1 all [upgradable from: 23.2.1-0ubuntu020.04.2]
N: There are 3 additional versions. Please use the '-a' switch to see them.
hann@HannYang:$ apt list --upgradable -a
Listing... Done
cloud-init/focal-updates 23.2.2-0ubuntu020.04.1 all [upgradable from: 23.2.1-0ubuntu020.04.2]
cloud-init/now 23.2.1-0ubuntu020.04.2 all [installed,upgradable to: 23.2.2-0ubuntu020.04.1]
cloud-init/focal-security 23.1.2-0ubuntu0~20.04.2 all
cloud-init/focal 20.1-10-g71af48df-0ubuntu5 all

更新升级操作：

hann@HannYang:~$ **sudo apt upgrade **
[sudo] password for hann: **********
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
Get more security updates through Ubuntu Pro with 'esm-apps' enabled:
exo-utils python2.7-minimal python2.7 libexo-2-0 libexo-common
libpython2.7-minimal libpython2.7-stdlib libexo-helpers
Learn more about Ubuntu Pro at https://ubuntu.com/pro
#

You can verify the status of security fixes using the pro fix command.

E.g., a recent Ruby vulnerability can be checked with: pro fix USN-6219-1

For more detail see: https://ubuntu.com/security/notices/USN-6219-1

The following packages will be upgraded:
cloud-init
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 532 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 cloud-init all 23.2.2-0ubuntu020.04.1 [532 kB]
Fetched 532 kB in 2s (226 kB/s)
Preconfiguring packages ...
(Reading database ... 156073 files and directories currently installed.)
Preparing to unpack .../cloud-init_23.2.2-0ubuntu020.04.1_all.deb ...
Unpacking cloud-init (23.2.2-0ubuntu020.04.1) over (23.2.1-0ubuntu020.04.2) ...
Setting up cloud-init (23.2.2-0ubuntu020.04.1) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for rsyslog (8.2001.0-1ubuntu1.3) ...
hann@HannYang:$ sudo apt upgrade cloud-init/focal-updates cloud-init/now cloud-init/focal-security cloud-init/focal
Reading package lists... Done
Building dependency tree
Reading state information... Done
cloud-init is already the newest version (23.2.2-0ubuntu020.04.1).
Selected version '23.2.2-0ubuntu020.04.1' (Ubuntu:20.04/focal-updates [all]) for 'cloud-init'
Selected version '23.2.2-0ubuntu020.04.1' (Ubuntu:20.04/focal-updates [all]) for 'cloud-init'
Selected version '23.1.2-0ubuntu020.04.2' (Ubuntu:20.04/focal-security [all]) for 'cloud-init'
Selected version '23.2.2-0ubuntu0~20.04.1' (Ubuntu:20.04/focal-updates [all]) for 'cloud-init'
Calculating upgrade... Done
Get more security updates through Ubuntu Pro with 'esm-apps' enabled:
exo-utils python2.7-minimal python2.7 libexo-2-0 libexo-common
libpython2.7-minimal libpython2.7-stdlib libexo-helpers
Learn more about Ubuntu Pro at https://ubuntu.com/pro
#

You can verify the status of security fixes using the pro fix command.

E.g., a recent Ruby vulnerability can be checked with: pro fix USN-6219-1

For more detail see: https://ubuntu.com/security/notices/USN-6219-1

0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
hann@HannYang:~$ apt list --upgradable
Listing... Done

版本号查询：

hann@HannYang:~$ cat /etc/issue
Ubuntu 20.04.6 LTS \n \l

hann@HannYang:~$ uname -r
5.15.90.4-microsoft-standard-WSL2

本次操作仅为日常升级更新，Ubuntu版本及Linux内核版本都没有升级。