Ubuntu 20.04 Focal 升级 Ubuntu 22.04 Jammy
本文将指导如何升级 Ubuntu 20.04 Focal 到 Ubuntu 22.04 Jammy。
前言
Ubuntu 22.04 Jammy Jellyfish 已正式发布，如果您使用 Ubuntu 20.04，那么可以参考本站教程升级。
准备工作
除非你是物理服务器，以及没有用过奇奇怪怪定制或修改的内核的 KVM 构架的 VPS 和云主机，否则升级大版本更新内核是有一定机率导致 Grub 加载失败的，切记备份重要数据！
OpenVZ 6 和 LXC 构架的 VPS 是无法升级的，因为他们没有自己独立的内核
再强调一遍，一定要备份重要数据！
以下操作需要在 root 用户下完成，请使用 sudo -i 或 su root 切换到 root 用户进行操作
更新系统
首先需要更新你当前的系统
apt update
apt upgrade -y
apt dist-upgrade -y
apt autoclean
apt autoremove -y
如果内核更新了，建议重启让最新的内核生效。
升级系统
我们有两种方法升级到最新的系统，第一种是和 Debian 类似，手工修改 apt 源文件：
首先更新 apt 源，替换 focal 为 jammy：
sed -i 's/focal/jammy/g' /etc/apt/sources.list
sed -i 's/focal/jammy/g' /etc/apt/sources.list.d/*.list
默认的系统 apt 源文件 /etc/apt/sources.list 应该是类似这样的：
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu/ jammy main restricted
# deb-src http://archive.ubuntu.com/ubuntu/ jammy main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu/ jammy-updates main restricted
# deb-src http://archive.ubuntu.com/ubuntu/ jammy-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu/ jammy universe
# deb-src http://archive.ubuntu.com/ubuntu/ jammy universe
deb http://archive.ubuntu.com/ubuntu/ jammy-updates universe
# deb-src http://archive.ubuntu.com/ubuntu/ jammy-updates universe
## N.B. 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.
deb http://archive.ubuntu.com/ubuntu/ jammy multiverse
# deb-src http://archive.ubuntu.com/ubuntu/ jammy multiverse
deb http://archive.ubuntu.com/ubuntu/ jammy-updates multiverse
# deb-src http://archive.ubuntu.com/ubuntu/ jammy-updates multiverse
## N.B. 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.
deb http://archive.ubuntu.com/ubuntu/ jammy-backports main restricted universe multiverse
# deb-src http://archive.ubuntu.com/ubuntu/ jammy-backports main restricted universe multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu jammy partner
# deb-src http://archive.canonical.com/ubuntu jammy partner
deb http://archive.ubuntu.com/ubuntu jammy-security main restricted
# deb-src http://archive.ubuntu.com/ubuntu jammy-security main restricted
deb http://archive.ubuntu.com/ubuntu jammy-security universe
# deb-src http://archive.ubuntu.com/ubuntu jammy-security universe
deb http://archive.ubuntu.com/ubuntu jammy-security multiverse
# deb-src http://archive.ubuntu.com/ubuntu jammy-security multiverse
国内服务器可以替换 archive.ubuntu.com 为 mirrors.tuna.tsinghua.edu.cn
然后我们再次执行更新系统：
apt update
apt upgrade -y
apt dist-upgrade -y
更新过程种会提示一些软件是否需要自动重启，选 Yes 即可，以及一些软件的配置文件是否需要更新，按照自己的情况选择即可，默认回车即视为使用旧的配置文件，一般会出现在 OpenSSH 等软件的更新上。
更新后删除不必要的软件和依赖：
apt autoclean
apt autoremove -y
然后我们使用 reboot 命令重启系统，耐心等待后，查看最新的系统版本：
root@ubuntu ~ # lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 22.04 LTS
Release: 22.04
Codename: jammy
root@ubuntu ~ # uname -a
Linux ubuntu 5.15.0-25 #4-Ubuntu SMP Fri Apr 1 07:36:38 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
这时我们就已经更新到了最新的 Ubuntu 22.04 Jammy 和内核了。
第二种方法是使用 do-release-upgrade 命令
首先安装 update-manager-core 软件包：
apt install update-manager-core
然后运行 do-release-upgrade -d 即可更新，其他方法和上面一样，不再详细解释。
如果添加过一些 PPA 源，如果他们还未发布最新版本的软件，可以临时先取消，比如
add-apt-repository --remove ppa:ondrej/php