Linux run node js

How To Install Node.js on Ubuntu 20.04

Node.js is a JavaScript runtime for server-side programming. It allows developers to create scalable backend functionality using JavaScript, a language many are already familiar with from browser-based web development.

In this guide, we will show you three different ways of getting Node.js installed on an Ubuntu 20.04 server:

• using apt to install the nodejs package from Ubuntu’s default software repository
• using apt with an alternate PPA software repository to install specific versions of the nodejs package
• installing nvm , the Node Version Manager, and using it to install and manage multiple versions of Node.js

For many users, using apt with the default repo will be sufficient. If you need specific newer or legacy versions of Node, you should use the PPA repository. If you are actively developing Node applications and need to switch between node versions frequently, choose the nvm method.

Prerequisites

To follow this guide, you will need an Ubuntu 20.04 server set up. Before you begin, you should have a non-root user account with sudo privileges set up on your system. You can learn how to do this by following the Ubuntu 20.04 initial server setup tutorial.

Option 1 — Installing Node.js with Apt from the Default Repositories

Ubuntu 20.04 contains a version of Node.js in its default repositories that can be used to provide a consistent experience across multiple systems. At the time of writing, the version in the repositories is 10.19. This will not be the latest version, but it should be stable and sufficient for quick experimentation with the language.

Warning: the version of Node.js included with Ubuntu 20.04, version 10.19, is now unsupported and unmaintained. You should not use this version in production, and should refer to one of the other sections in this tutorial to install a more recent version of Node.

To get this version, you can use the apt package manager. Refresh your local package index first:

Check that the install was successful by querying node for its version number:

If the package in the repositories suits your needs, this is all you need to do to get set up with Node.js. In most cases, you’ll also want to also install npm , the Node.js package manager. You can do this by installing the npm package with apt :

This allows you to install modules and packages to use with Node.js.

At this point, you have successfully installed Node.js and npm using apt and the default Ubuntu software repositories. The next section will show how to use an alternate repository to install different versions of Node.js.

Option 2 — Installing Node.js with Apt Using a NodeSource PPA

To install a different version of Node.js, you can use a PPA (personal package archive) maintained by NodeSource. These PPAs have more versions of Node.js available than the official Ubuntu repositories. Node.js v16 and v18 are available as of the time of writing.

First, install the PPA to get access to its packages. From your home directory, use curl to retrieve the installation script for your preferred version, making sure to replace 16.x with your preferred version string (if different):

Refer to the NodeSource documentation for more information on the available versions.

Inspect the contents of the downloaded script with nano or your preferred text editor:

When you are satisfied that the script is safe to run, exit your editor. Then run the script with sudo :

The PPA will be added to your configuration and your local package cache will be updated automatically. You can now install the Node.js package in the same way you did in the previous section:

Verify that you’ve installed the new version by running node with the -v version flag:

The NodeSource nodejs package contains both the node binary and npm , so you don’t need to install npm separately.

At this point, you have successfully installed Node.js and npm using apt and the NodeSource PPA. The next section will show how to use the Node Version Manager to install and manage multiple versions of Node.js.

Option 3 — Installing Node Using the Node Version Manager

Another way of installing Node.js that is particularly flexible is to use nvm, the Node Version Manager. This piece of software allows you to install and maintain many different independent versions of Node.js, and their associated Node packages, at the same time.

To install NVM on your Ubuntu 20.04 machine, visit the project’s GitHub page. Copy the curl command from the README file that displays on the main page. This will get you the most recent version of the installation script.

Before piping the command through to bash , it is always a good idea to audit the script to make sure it isn’t doing anything you don’t agree with. You can do that by removing the | bash segment at the end of the curl command:

Review the script and make sure you are comfortable with the changes it is making. When you are satisfied, run the command again with | bash appended at the end. The URL you use will change depending on the latest version of nvm, but as of right now, the script can be downloaded and executed with the following:

This will install the nvm script to your user account. To use it, you must first source your .bashrc file:

Now, you can ask NVM which versions of Node are available:

Output
. . . v18.0.0 v18.1.0 v18.2.0 v18.3.0 v18.4.0 v18.5.0 v18.6.0 v18.7.0 v18.8.0 v18.9.0 v18.9.1 v18.10.0 v18.11.0 v18.12.0 (LTS: Hydrogen) v18.12.1 (LTS: Hydrogen) v18.13.0 (Latest LTS: Hydrogen) v19.0.0 v19.0.1 v19.1.0 v19.2.0 v19.3.0 v19.4.0 

It’s a very long list. You can install a version of Node by writing in any of the release versions listed. For instance, to get version v14.10.0, you can run:

You can view the different versions you have installed by listing them:

Output
-> v14.10.0 v14.21.2 default -> v14.10.0 iojs -> N/A (default) unstable -> N/A (default) node -> stable (-> v14.21.2) (default) stable -> 14.21 (-> v14.21.2) (default) . . . 

This shows the currently active version on the first line ( -> v14.10.0 ), followed by some named aliases and the versions that those aliases point to.

Note: if you also have a version of Node.js installed through apt , you may receive a system entry here. You can always activate the system-installed version of Node using nvm use system .

Additionally, there are aliases for the various long-term support (or LTS) releases of Node:

Output
lts/* -> lts/hydrogen (-> N/A) lts/argon -> v4.9.1 (-> N/A) lts/boron -> v6.17.1 (-> N/A) lts/carbon -> v8.17.0 (-> N/A) lts/dubnium -> v10.24.1 (-> N/A) lts/erbium -> v12.22.12 (-> N/A) lts/fermium -> v14.21.2 lts/gallium -> v16.19.0 (-> N/A) lts/hydrogen -> v18.13.0 (-> N/A) 

You can install a release based on these aliases as well. For instance, to install the latest long-term support version, hydrogen , run the following:

Output
Downloading and installing node v18.13.0. . . . Now using node v18.13.0 (npm v8.19.3) 

You can switch between installed versions with nvm use :

Output
Now using node v14.10.0 (npm v6.14.8) ``` You can verify that the install was successful using the same technique from the other sections: ```command node -v 

The correct version of Node is installed on your machine as expected. A compatible version of npm is also available.

Removing Node.js

You can uninstall Node.js using apt or nvm , depending on how it was installed. To remove the version from the system repositories, use apt remove :

By default, apt remove retains any local configuration files that were created since installation. If you don’t want to save the configuration files for later use, use apt purge :

To uninstall a version of Node.js that you installed using nvm , first determine whether it is the current active version:

If the version you are targeting is not the current active version, you can run:

Output
Uninstalled node node_version 

This command will uninstall the selected version of Node.js.

If the version you would like to remove is the current active version, you first need to deactivate nvm to enable your changes:

Now you can uninstall the current version using the uninstall command used previously. This removes all files associated with the targeted version of Node.js.

Conclusion

There are quite a few ways to get up and running with Node.js on your Ubuntu 20.04 server. Your circumstances will dictate which of the above methods is best for your needs. While using the packaged version in Ubuntu’s repository is one method, using nvm or a NodeSource PPA offers additional flexibility.

For more information on programming with Node.js, please refer to our tutorial series How To Code in Node.js.

DigitalOcean provides multiple options for deploying Node.js applications, from our simple, affordable virtual machines to our fully-managed App Platform offering. Easily host your Node.js application on DigitalOcean in seconds.

Tutorial Series: How to Install Node.js and Create a Local Development Environment

Node.js is a JavaScript platform for general-purpose programming that allows users to build network applications quickly. By leveraging JavaScript on both the front and backend, Node.js makes development more consistent and integrated.

To get your development environment configured so you can start building Node.js applications. select the tutorial for your platform.

Источник

Run Node.js scripts from the command line

The usual way to run a Node.js program is to run the globally available node command (once you install Node.js) and pass the name of the file you want to execute.

If your main Node.js application file is app.js , you can call it by typing:

Above, you are explicitly telling the shell to run your script with node . You can also embed this information into your JavaScript file with a «shebang» line. The «shebang» is the first line in the file, and tells the OS which interpreter to use for running the script. Below is the first line of JavaScript:

Above, we are explicitly giving the absolute path of interpreter. Not all operating systems have node in the bin folder, but all should have env . You can tell the OS to run env with node as parameter:

To use a shebang, your file should have executable permission. You can give app.js the executable permission by running:

While running the command, make sure you are in the same directory which contains the app.js file.

Pass string as argument to node instead of file path

To execute a string as argument you can use -e , —eval «script» . Evaluate the following argument as JavaScript. The modules which are predefined in the REPL can also be used in script.

On Windows, using cmd.exe a single quote will not work correctly because it only recognizes double » for quoting. In Powershell or Git bash, both ‘ and » are usable.

Restart the application automatically

The node command has to be re-executed in bash whenever there is a change in the application. To restart the application automatically, use the nodemon module.

Install the nodemon module globally to system path:

You can also install nodemon as a development dependency:

This local installation of nodemon can be run by calling it from within npm script such as npm start or using npx nodemon.

Run the application using the nodemon command followed by the application’s file name:

Источник