我之前使用 ubuntu16.04 升级到 ubuntu 18.04。按照一些教程删除了 npm，但现在卡住了。我有：
~$ npm list -g
bash: /usr/bin/npm: No such file or directory
和：
sudo apt-get install npm
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
npm : Depends: nodejs but it is not going to be installed
Depends: node-abbrev (>= 1.0.4) but it is not going to be installed
Depends: node-ansi (>= 0.3.0-2) but it is not going to be installed
Depends: node-ansi-color-table but it is not going to be installed
Depends: node-archy but it is not going to be installed
Depends: node-block-stream but it is not going to be installed
Depends: node-fstream (>= 0.1.22) but it is not going to be installed
Depends: node-fstream-ignore but it is not going to be installed
Depends: node-github-url-from-git but it is not going to be installed
Depends: node-glob (>= 3.1.21) but it is not going to be installed
Depends: node-graceful-fs (>= 2.0.0) but it is not going to be installed
Depends: node-inherits but it is not going to be installed
Depends: node-ini (>= 1.1.0) but it is not going to be installed
Depends: node-lockfile but it is not going to be installed
Depends: node-lru-cache (>= 2.3.0) but it is not going to be installed
Depends: node-minimatch (>= 0.2.11) but it is not going to be installed
Depends: node-mkdirp (>= 0.3.3) but it is not going to be installed
Depends: node-gyp (>= 0.10.9) but it is not going to be installed
Depends: node-nopt (>= 3.0.1) but it is not going to be installed
Depends: node-npmlog but it is not going to be installed
Depends: node-once but it is not going to be installed
Depends: node-osenv but it is not going to be installed
Depends: node-read but it is not going to be installed
Depends: node-read-package-json (>= 1.1.0) but it is not going to be installed
Depends: node-request (>= 2.25.0) but it is not going to be installed
Depends: node-retry but it is not going to be installed
Depends: node-rimraf (>= 2.2.2) but it is not going to be installed
Depends: node-semver (>= 2.1.0) but it is not going to be installed
Depends: node-sha but it is not going to be installed
Depends: node-slide but it is not going to be installed
Depends: node-tar (>= 0.1.18) but it is not going to be installed
Depends: node-underscore but it is not going to be installed
Depends: node-which but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
答案1
跟进：在 Ubuntu 上安装 nodejs 的最新说明。 Nodejs 官方文档
原始答案如下。
我也遇到了同样的问题。在网上搜索了很多次后，我终于找到了解决方案。
以下是为我解决问题的方法：
删除旧的 nodejs 安装和更新包。
sudo apt-get remove nodejs npm
sudo apt-get update
sudo apt-get upgrade
对于 8.x 节点安装：
curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -
对于 12.x 节点安装：
curl -sL https://deb.nodesource.com/setup_12.x | sudo -E bash -
安装：
sudo apt-get install -y nodejs
测试安装：
~$ nodejs -v
v8.11.3 // <- node 8.x
v12.13.1 // <- node 12.x
~$ npm -v
5.6.0 // <- node 8.x
6.12.1 // <- node 12.x