最新的 Ubuntu LTS 版本 Ubuntu 18.04 (Bionic Beaver) 于 2018 年 4 月 26 日发布，支持期为 5 年，直至 2023 年 4 月。在本教程中，我们将向您展示如何升级 Ubuntu 16.04 安装或更高版本到 Ubuntu 18.04（仿生海狸）。
先决条件#
在开始学习本教程之前，请确保您以以下身份登录具有 sudo 权限的用户
.
备份您的数据#
首先也是最重要的，请确保在开始操作系统的重大升级之前备份数据。如果您在虚拟机上运行 Ubuntu，最好拍摄完整的系统快照，以便在更新失败时可以轻松恢复您的计算机。
更新当前安装的软件包#
在开始版本升级之前，建议将当前安装的所有软件包更新到最新版本。
sudo apt updatesudo apt upgrade
我们也会跑dist-upgrade这将对已安装的软件包执行主要版本升级，并可能删除一些不必要的软件包：
sudo apt dist-upgrade
将 Ubuntu 16.04 升级到 Ubuntu 18.04#
Ubuntu提供了一个工具叫do-release-upgrade这使得升级过程非常简单。
该工具应该已经安装在您的系统上，但如果由于某种原因未安装，您可以使用以下命令安装它：
sudo apt install update-manager-core
开始升级运行do-release-upgrade:
sudo do-release-upgrade
如果您像我一样通过 SSH 升级系统，系统会询问您是否要继续。
Reading cache
Checking package manager
Continue running under SSH?
This session appears to be running under ssh. It is not recommended
to perform an upgrade over ssh currently because in case of failure it
is harder to recover.
If you continue, an additional ssh daemon will be started at port
'1022'.
Do you want to continue?
Continue [yN]
Starting additional sshd
To make recovery in case of failure easier, an additional sshd will
be started on port '1022'. If anything goes wrong with the running
ssh you can still connect to the additional one.
If you run a firewall, you may need to temporarily open this port. As
this is potentially dangerous it's not done automatically. You can
open the port with e.g.:
'iptables -I INPUT -p tcp --dport 1022 -j ACCEPT'
To continue please press [ENTER]
升级工具下载软件包列表并计算更改后，它会询问您是否要继续。
Do you want to start the upgrade?
4 installed packages are no longer supported by Canonical. You can
still get support from the community.
3 packages are going to be removed. 90 new packages are going to be
installed. 397 packages are going to be upgraded.
You have to download a total of 267 M. This download will take about
1 minute with your connection.
Installing the upgrade can take several hours. Once the download has
finished, the process cannot be canceled.
再次输入y然后升级过程将开始。
在升级过程中，系统会询问您各种问题，例如是否要保留现有配置文件或安装软件包维护者的版本。如果您没有对文件进行任何自定义更改，则应该可以安全地键入Y否则要保持当前配置输入N.
Configuration file '/etc/sysctl.conf'
==> Modified (by you or by a script) since installation.
==> Package distributor has shipped an updated version.
What would you like to do about it ? Your options are:
Y or I : install the package maintainer's version
N or O : keep your currently-installed version
D : show the differences between the versions
Z : start a shell to examine the situation
The default action is to keep your current version.
*** sysctl.conf (Y/I/N/O/D/Z) [default=N] ?
升级过程可能需要一些时间，具体取决于更新数量和您的互联网速度。
安装新软件包后，更新工具会询问您是否要删除过时的软件，如果您不确定，请输入d并检查过时的软件包列表，大多数情况下输入是安全的y并删除所有过时的包：
Searching for obsolete software
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading state information... Done
Remove obsolete packages?
17 packages are going to be removed.
升级过程完成并假设一切顺利后，系统会要求您重新启动计算机。类型y接着说：
System upgrade is complete.
Restart required
To finish the upgrade, a restart is required.
If you select 'y' the system will be restarted.
Continue [yN] y
确认更新#
等待一段时间，直到服务器重新启动，然后重新连接。登录后，您将收到以下消息：
Welcome to Ubuntu 18.04 LTS (GNU/Linux 4.15.0-20-generic x86_64)
您还可以使用以下命令检查Ubuntu版本：
lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04 LTS
Release: 18.04
Codename: bionic
就这样，您现在可以享受新的 Ubuntu 18.04 LTS（Bionic Beaver）了。
