An important aspect of web components is encapsulation — being able to keep the markup structure, style, and behavior hidden and separate from other code on the page so that different parts do not clash, and the code can be kept nice and clean. The Shadow DOM API is a key part of this, providing a way to attach a hidden separated DOM to an element. This article covers the basics of using the Shadow DOM.



<blockquote class="wp-block-quote">Note: Shadow DOM is supported by default in Firefox (63 and onwards), Chrome, Opera, and Safari. The new Chromium-based Edge (79 and onwards) supports it too; the old Edge didn't.</blockquote>



<h2>High-level view</h2>



This article assumes you are already familiar with the concept of the <a href="https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model/Introduction" target="_blank" rel="noreferrer noopener nofollow">DOM (Document Object Model)</a> — a tree-like structure of connected nodes that represents the different elements and strings of text appearing in a markup document (usually an HTML document in the case of web documents). As an example, consider the following HTML fragment:



<pre class="wp-block-code"><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
 &lt;head&gt;
 &lt;meta charset="utf-8"&gt;
 &lt;title&gt;Simple DOM example&lt;/title&gt;
 &lt;/head&gt;
 &lt;body&gt;
 &lt;section&gt;
 &lt;img src="dinosaur.png" alt="A red Tyrannosaurus Rex: A two legged dinosaur standing upright like a human, with small arms, and a large head with lots of sharp teeth."&gt;
 &lt;p&gt;Here we will add a link to the &lt;a href="https://www.mozilla.org/"&gt;Mozilla homepage&lt;/a&gt;&lt;/p&gt;
 &lt;/section&gt;
 &lt;/body&gt;
&lt;/html&gt;</code></pre>



This fragment produces the following DOM structure:



<figure class="wp-block-image size-full"><img src="https://tcmhack.in/wp-content/uploads/2021/09/dom-screenshot.png" alt="" class="wp-image-869"/></figure>



Shadow DOM allows hidden DOM trees to be attached to elements in the regular DOM tree — this shadow DOM tree starts with a shadow root, underneath which can be attached to any elements you want, in the same way as the normal DOM.



<figure class="wp-block-image size-large"><img src="https://tcmhack.in/wp-content/uploads/2021/09/shadowdom-1-1024x471.png" alt="" class="wp-image-870"/></figure>



There are some bits of shadow DOM terminology to be aware of:



<ul><li>Shadow host: The regular DOM node that the shadow DOM is attached to.</li><li>Shadow tree: The DOM tree inside the shadow DOM.</li><li>Shadow boundary: the place where the shadow DOM ends, and the regular DOM begins.</li><li>Shadow root: The root node of the shadow tree.</li></ul>



You can affect the nodes in the shadow DOM in exactly the same way as non-shadow nodes — for example appending children or setting attributes, styling individual nodes using element.style.foo, or adding style to the entire shadow DOM tree inside a<a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/style" target="_blank" rel="noreferrer noopener nofollow"> <code>&lt;style&gt;</code></a> element. The difference is that none of the code inside a shadow DOM can affect anything outside it, allowing for handy encapsulation.



Note that the shadow DOM is not a new thing by any means — browsers have used it for a long time to encapsulate the inner structure of an element. Think for example of a <code><a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/video" target="_blank" rel="noreferrer noopener nofollow">&lt;video&gt;</a></code> element, with the default browser controls exposed. All you see in the DOM is the <code>&lt;video&gt;</code> element, but it contains a series of buttons and other controls inside its shadow DOM. The shadow DOM spec has made it so that you are allowed to actually manipulate the shadow DOM of your own custom elements.



<h2>Basic usage</h2>



You can attach a shadow root to any element using the&nbsp;<a href="https://developer.mozilla.org/en-US/docs/Web/API/Element/attachShadow" target="_blank" rel="noreferrer noopener nofollow"><code>Element.attachShadow()</code></a>&nbsp;method. This takes as its parameter an options object that contains one option —&nbsp;<code>mode</code>&nbsp;— with a value of&nbsp;<code>open</code>&nbsp;or&nbsp;<code>closed</code>:



<pre class="wp-block-code"><code>let shadow = elementRef.attachShadow({mode: 'open'});
let shadow = elementRef.attachShadow({mode: 'closed'});</code></pre>



<code>open</code>&nbsp;means that you can access the shadow DOM using JavaScript written in the main page context, for example using the&nbsp;<a href="https://developer.mozilla.org/en-US/docs/Web/API/Element/shadowRoot" target="_blank" rel="noreferrer noopener nofollow"><code>Element.shadowRoot</code></a>&nbsp;property:



<pre class="wp-block-code"><code>let myShadowDom = myCustomElem.shadowRoot;</code></pre>



If you attach a shadow root to a custom element with&nbsp;<code>mode: closed</code>&nbsp;set, you won't be able to access the shadow DOM from the outside —&nbsp;<code>myCustomElem.shadowRoot</code>&nbsp;returns&nbsp;<code>null</code>. This is the case with built in elements that contain shadow DOMs, such as&nbsp;<code>&lt;video&gt;</code>.



Note: As&nbsp;<a href="https://blog.revillweb.com/open-vs-closed-shadow-dom-9f3d7427d1af" target="_blank" rel="noreferrer noopener nofollow">this blog post shows</a>, it is actually fairly easy to work around closed shadow DOMs, and the hassle to completely hide them is often more than it's worth.



If you are attaching a shadow DOM to a custom element as part of its constructor (by far the most useful application of the shadow DOM), you would use something like this:



<pre class="wp-block-code"><code>let shadow = this.attachShadow({mode: 'open'});</code></pre>



When you've attached a shadow DOM to an element, manipulating it is a matter of just using the same DOM APIs as you use for the regular DOM manipulation:



<pre class="wp-block-code"><code>let para = document.createElement('p');
shadow.appendChild(para);
// etc.</code></pre>



<h2 id="working_through_a_simple_example">Working through a simple example</h2>



Now let's walk through a simple example to demonstrate the shadow DOM in action inside a custom element —&nbsp;<code><a href="https://github.com/mdn/web-components-examples/tree/master/popup-info-box-web-component" target="_blank" rel="noreferrer noopener nofollow">&lt;popup-info&gt;</a></code>&nbsp;(see a&nbsp;<a href="https://mdn.github.io/web-components-examples/popup-info-box-web-component/" target="_blank" rel="noreferrer noopener nofollow">live example</a>&nbsp;also). This takes an image icon and a text string, and embeds the icon into the page. When the icon is focused, it displays the text in a pop up information box to provide further in-context information. To begin with, in our JavaScript file we define a class called&nbsp;<code>PopUpInfo</code>, which extends&nbsp;<code>HTMLElement</code>:



<pre class="wp-block-code"><code>class PopUpInfo extends HTMLElement {
 constructor() {
 // Always call super first in constructor
 super();

 // write element functionality in here

 ...
 }
}</code></pre>



Inside the class definition we define the element's constructor, which defines all the functionality the element will have when an instance of it is instantiated.



<h3 id="creating_the_shadow_root">Creating the shadow root</h3>



We first attach a shadow root to the custom element:



<pre class="wp-block-code"><code>// Create a shadow root
let shadow = this.attachShadow({mode: 'open'});</code></pre>



<h3 id="creating_the_shadow_dom_structure">Creating the shadow DOM structure</h3>



Next, we use some DOM manipulation to create the element's internal shadow DOM structure:



<pre class="wp-block-code"><code>// Create spans
let wrapper = document.createElement('span');
wrapper.setAttribute('class', 'wrapper');
let icon = document.createElement('span');
icon.setAttribute('class', 'icon');
icon.setAttribute('tabindex', 0);
let info = document.createElement('span');
info.setAttribute('class', 'info');

// Take attribute content and put it inside the info span
let text = this.getAttribute('data-text');
info.textContent = text;

// Insert icon
let imgUrl;
if(this.hasAttribute('img')) {
 imgUrl = this.getAttribute('img');
} else {
 imgUrl = 'img/default.png';
}
let img = document.createElement('img');
img.src = imgUrl;
icon.appendChild(img);
</code></pre>



<h3 id="styling_the_shadow_dom">Styling the shadow DOM</h3>



After that we create a&nbsp;<a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/style" target="_blank" rel="noreferrer noopener nofollow"><code>&lt;style&gt;</code></a>&nbsp;element and populate it with some CSS to style it:



<pre class="wp-block-code"><code>// Create some CSS to apply to the shadow dom
let style = document.createElement('style');

style.textContent = `
.wrapper {
 position: relative;
}

.info {
 font-size: 0.8rem;
 width: 200px;
 display: inline-block;
 border: 1px solid black;
 padding: 10px;
 background: white;
 border-radius: 10px;
 opacity: 0;
 transition: 0.6s all;
 position: absolute;
 bottom: 20px;
 left: 10px;
 z-index: 3;
}

img {
 width: 1.2rem;
}

.icon:hover + .info, .icon:focus + .info {
 opacity: 1;
}`;</code></pre>



<h3 id="attaching_the_shadow_dom_to_the_shadow_root">Attaching the shadow DOM to the shadow root</h3>



The final step is to attach all the created elements to the shadow root:



<pre class="wp-block-code"><code>// attach the created elements to the shadow dom
shadow.appendChild(style);
shadow.appendChild(wrapper);
wrapper.appendChild(icon);
wrapper.appendChild(info);</code></pre>



Feel free to ask a question in comments.

An important aspect of web components is encapsulation — being able to keep the markup structure, style, and behavior hidden and separate from ot...

Shadow DOM in JavaScript - TCMHACK

Shadow DOM in JavaScript

<a href="https://www.microsoft.com/en-us/edge/features" target="_blank" rel="noreferrer noopener nofollow">Microsoft Edge</a> is a fast, easy to use, and secure browser built for the modern web. The stable browser version is available on Windows, macOS, iOS, and Android, while the developer preview is available for Linux. Edge allows you to synchronize your bookmarks, history, and passwords on all your devices.

Edge is based on Chromium, the same open-source project used by Google Chrome browser, and it is compatible with the Chrome extensions.

This article explains how to install the Microsoft Edge Browser web browser on Ubuntu. The Edge developer preview does not include all the features and may not be stable enough to be used as the main browser.

<h2>Installing Edge Browser on Ubuntu</h2>

Installing Edge browser on Ubuntu is a pretty straightforward process. We&rsquo;ll enable the Microsoft Edge repository from the command-line and install the package with apt.

<ol>
<li>Update the packages index and install the dependencies by running the following command as a user with sudo privileges :</li>
</ol>

<pre id="block-d85b3eb6-be73-40e1-8372-e0b120f7abdc" class="wp-block-code"><code>sudo apt update sudo apt install software-properties-common apt-transport-https wget</code></pre>

2. Import the Microsoft GPG key with wget :

<pre class="wp-block-code"><code>wget -q https://packages.microsoft.com/keys/microsoft.asc -O- | sudo apt-key add -</code></pre>

And enable the Edge browser repository by typing:

<pre class="wp-block-code"><code>sudo add-apt-repository "deb [arch=amd64] https://packages.microsoft.com/repos/edge stable main"</code></pre>

3. Once the apt repository is enabled , install the Edge package:

<pre class="wp-block-code"><code>sudo apt install microsoft-edge-dev</code></pre>

At this point, you have Edge installed on your Ubuntu system.

When a new version is released, you can update the Edge package through your desktop standard Software Update tool or by running the following commands in your terminal:

<pre class="wp-block-code"><code>sudo apt update sudo apt upgrade</code></pre>

<h2>Starting Edge Browser</h2>

In the Activities search bar, type &ldquo;Edge&rdquo; and click on the icon to launch the application:
<img src="../../../../uploads/blogs/ms-edge-install-1024x633.png" alt="ms edge install" width="1024" height="633">

Edge can also be launched from the command-line by typing <code>microsoft-edge</code>.

When you start the browser for the first time, a window like the following will appear asking if you want to send usage statistic and diagnostic data to Microsoft:
<img src="../../../../uploads/blogs/ms-edge-start-1024x642.png" alt="ms edge start" width="1024" height="642">

Select according to your preference, and click OK to proceed.

From here, you can set up your new tab page, change the browser settings and install add-ons.

<h3>Conclusion</h3>

We&rsquo;ve shown you how to install Microsoft Edge on your Ubuntu 20.04 desktop machine.

If you&rsquo;ve previously used a different browser, like&nbsp;Chrome&nbsp;, Firefox,&nbsp;Chromium&nbsp;, or Opera, you can import your bookmarks and settings into Edge.

Feel free to leave a comment below.

Microsoft Edge is a fast, easy to use, and secure browser built for the modern web. The stable browser version is available on Windows, macOS, iO...

How to Install Microsoft Edge Browser on Ubuntu - TCMHACK

How to Install Microsoft Edge Browser on Ubuntu

Many developers use <a href="https://github.com/facebook/create-react-app" target="_blank" rel="noreferrer noopener nofollow">create-react-app</a> to generate a boilerplate needed to quickly start developing a React application. It gives you the option to define Environment Variables is a special file named <code>.env.</code>

All variables defined in this file are accessible in the code via <code>process.env..</code>

<h2>Define Environment Variable</h2>

First, open the project and create <code>.env</code> file in the root directory:
<img src="../../../../uploads/1744605242855-react-env-1.png" alt="" width="649" height="260">

To define Environment Variable, open the .env file and paste the following code:

<pre class="wp-block-code"><code>MY_ENVIRONMENT_VARIABLE=test</code></pre>

We have just defined our first variable, great.

Next, save the changes, close the file and navigate to App.js and read the variable:

<pre class="wp-block-code"><code>const App = () =&gt; {
 console.log(process.env.MY_ENVIRONMENT_VARIABLE);
 return &lt;div className="App"&gt;Hello, world&lt;/div&gt;;
};</code></pre>

Start the project: <code>NPM START</code>

And note that undefined was output to the console:
<img src="../../../../uploads/blogs/undefined-console-1024x106.png" alt="undefined console" width="1024" height="106">

Do you know why?

<h2>Gotcha #1</h2>

The first mistake we made is not reloading our app after defining an Environment Variable.

Remember that Environment Variables are embedded during build time.

Any change in the .env file requires an application to be reloaded.

Let's do this and try again:
<img src="../../../../uploads/1744605424029-undefined-console-1-1024x106.png" alt="" width="1024" height="106">

Still no success, let's find out why.

<h2>Gotcha #2</h2>

The second thing to remember is that, for security reasons, create-react-app does not allow you to define Environment Variables that do not start with the REACT_APP_ prefix.

Our variable name is definitely wrong and will not work.

Let's change it:

<pre class="wp-block-code"><code>REACT_APP_MY_ENVIRONMENT_VARIABLE=test</code></pre>

And in the App.js:

<pre class="wp-block-code"><code>const App = () =&gt; {
 console.log(process.env.REACT_APP_MY_ENVIRONMENT_VARIABLE);
 return &lt;div className="App"&gt;Hello, world&lt;/div&gt;;
};

export default App;</code></pre>

Reload an application and check the console:
<img src="../../../../uploads/1744605467698-success-console-1024x104.png" alt="" width="1024" height="104">

Hooray, we got it to work.

<h3>Summary</h3>

The two most important things to remember when defining Environment Variables in a project bootstrapped with create-react-app are:

<ul>
<li>Always reload your application after making a change to the .env file</li>
<li>Always prefix your variables with REACT_APP_</li>
</ul>

&nbsp;

Many developers use create-react-app to generate a boilerplate needed to quickly start developing a React application. It gives you the option to...

Can't Read Environment Variables In React? - TCMHACK

Can't Read Environment Variables In React?

With Google&rsquo;s new release of an SSL Certificates having a small ranking boost on search engine ranking, we&rsquo;ve decided to release an easy tutorial on installing the ssl certificates on an Amazon EC2 Ubuntu server.

For those wanting to check their version of Ubuntu you can run:

<pre class="wp-block-code"><code>lsb_release -a</code></pre>

This is what ours returned:

<pre class="wp-block-code"><code>No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.5 LTS
Release:	18.04
Codename:	bionic</code></pre>

So let&rsquo;s dive into what needs to be done to install Standard SSL Certificate with Amazon EC2.

<h2>MOVE SSL CERTIFICATES FILES TO SERVER</h2>

You need to move your ssl files to server. Follow the following steps.

1. SSH to your server

<pre class="wp-block-code"><code>ssh -i yourkey.pem ubuntu@your_server_ip_or_domain</code></pre>

2. Go to your html folder &amp; make a folder to hold the ssl files

<pre class="wp-block-code"><code>cd /var/www/html
sudo mkdir ssl_files</code></pre>

3. Now go to your folder in which ssl files are stored on your local machine &amp; open the terminal <code>CTRL+ALT+T on Ubuntu</code>

4. Move the files to server via <a href="https://tcmhack.in/how-to-upload-files-via-ssh-using-scp-on-ubuntu/">Secure Copy Protocal (SCP)</a> to your newly created folder i.e <code>ssl_files</code>. Don't know how to use SCP? <a href="https://tcmhack.in/how-to-upload-files-via-ssh-using-scp-on-ubuntu/">Click here</a>

6. Now SSH again to your server and move the certificate files to required place.

<pre class="wp-block-code"><code>ssh -i yourkey.pem ubuntu@your_server_ip_or_domain
cd /var/www/html/ssl_files

sudo cp your_site.crt /etc/apache2/ssl/your_site.crt
sudo cp your_site.key /etc/apache2/ssl/your_site.key
sudo cp your_site.ca-bundle /etc/apache2/ssl/your_site.ca-bundle</code></pre>

<h2>ADDING SSL VIRTUALHOST ENTRIES</h2>

At this point, all we need to do is enable the VHOST for our site to render the SSL pages. You will either need to create a new VHOST entry if its a new site, or add this to an existing entry for your site.

<pre class="wp-block-code"><code>&lt;VirtualHost *:443&gt;
 ServerName your_site.com
 ServerAlias www.your_site.com
 DocumentRoot /documentroot/
 SSLEngine on
 SSLCertificateFile /etc/apache2/ssl/your_site.crt
 SSLCertificateKeyFile /etc/apache2/ssl/private/your_site.key
 SSLCertificateChainFile /etc/apache2/ssl/your_site.ca-bundle
&lt;/VirtualHost&gt;</code></pre>

Restart the apache:

<pre class="wp-block-code"><code>sudo systemctl restart apache2</code></pre>

<h2>ENABLE APACHE 2 SSL MODULE IF NOT ENABLED ALREADY</h2>

Next thing to do if you haven&rsquo;t already is to enable the SSL module for Apache and then restarting apache. This is as simple as typing:

<pre class="wp-block-code"><code>sudo a2enmod ssl
sudo systemctl restart apache2</code></pre>

<h2>ENABLE SSL TRAFFIC ON AMAZON EC2</h2>

One last step is to ensure SSL traffic is enabled or your security group in Amazon. By default, Amazon does not enable this as not all sites will need it. Log in to your Amazon account, go to EC2 and your server instance. From their click on the Security Group assigned to your site, and enable HTTPs traffic for Inbound.
<img src="../../../../uploads/1744733376731-amazon-enabled-https-traffic.jpg" alt="" width="780" height="251">

Load your site and you should now be able to run https! Just make sure to redirect any http url&rsquo;s to https, so your not serving the same content up twice by mistake, as this would be bad for SEO and hurt your Google rankings. One main reason to add SSL is for Google rankings &mdash; we don&rsquo;t want to gain a little, and lose our seo by serving duplicate content.

That's it. If you're still facing the issues? feel free to ask the questions in comment section.

With Google’s new release of an SSL Certificates having a small ranking boost on search engine ranking, we’ve decided to release an easy tutorial...

How to install SSL Certificates on Amazon EC2 Ubuntu Server - TCMHACK

How to install SSL Certificates on Amazon EC2 Ubuntu Server

In this tutorial, we will show you how to use the&nbsp;<code>shutdown</code>&nbsp;command through practical examples and detailed explanations of the most common&nbsp;<code>shutdown</code>&nbsp;options.



The&nbsp;<code>shutdown</code>&nbsp;command brings the system down in a secure way. When the&nbsp;<code>shutdown</code>&nbsp;is initiated, all logged-in users and processes are notified that the system is going down, and no further logins are allowed. You can shut down your system immediately or at the specified time.



<h2 id="shutdown-command-syntax">Shutdown Command Syntax</h2>



Before going into how to use the&nbsp;<code>shutdown</code>&nbsp;command, let’s start by reviewing the basic syntax.



The&nbsp;<code>shutdown</code>&nbsp;command expressions take the following form:



<pre class="wp-block-code"><code>shutdown &#91;OPTIONS] &#91;TIME] &#91;MESSAGE]</code></pre>



<ul><li><code>options</code>&nbsp;-&nbsp;<a href="http://man7.org/linux/man-pages/man8/shutdown.8.html" target="_blank" rel="noreferrer noopener nofollow">Shutdown options</a>&nbsp;such as halt, power-off (the default option) or reboot the system.</li><li><code>time</code>&nbsp;- The time argument specifies when to perform the shutdown process.</li><li><code>message</code>&nbsp;- The message argument specifies a message which will be broadcast to all users.</li></ul>



On the recent Linux distributions&nbsp;<code>shutdown</code>&nbsp;is an alias to&nbsp;<code>systemctl</code>&nbsp;and it is available in the system only for compatibility reasons.



<h2 id="how-to-use-the-shutdown-command">How to Use the&nbsp;<code>shutdown</code>&nbsp;Command</h2>



Only the root and users with&nbsp;<code>sudo</code>&nbsp;privileges can use&nbsp;<code>crontab</code>&nbsp;command.



When used with no arguments, the&nbsp;<code>shutdown</code>&nbsp;command will power off the machine.



<pre class="wp-block-code"><code>sudo shutdown</code></pre>



<figure class="wp-block-image size-large"><img src="http://ec2-13-127-91-65.ap-south-1.compute.amazonaws.com/wp-content/uploads/2020/12/shutdown.jpg" alt="" class="wp-image-763"/></figure>



The shutdown process starts after 1 minute, which is the default time interval.



<h2 id="how-to-shutdown-the-system-at-a-specified-time">How to Shutdown the System at a Specified Time</h2>



The time argument can have two different formats. It can be an absolute time in the format&nbsp;<code>hh:mm</code>&nbsp;and relative time in the format&nbsp;<code>+m</code>&nbsp;where m is the number of minutes from now.



The following example will schedule system shutdown at 11 A.M:



<pre class="wp-block-code"><code>sudo shutdown 11:00</code></pre>



The following example will schedule system&nbsp;<code>shutdown</code>&nbsp;in 10 minutes from now:



<pre class="wp-block-code"><code>sudo shutdown +10</code></pre>



<h2 id="how-to-shutdown-the-system-immediately">How to Shutdown the System Immediately</h2>



To shut down your system immediately you can use&nbsp;<code>+0</code>&nbsp;or its alias&nbsp;<code>now</code>:



<pre class="wp-block-code"><code>sudo shutdown now</code></pre>



<h2 id="how-to-broadcast-a-custom-message">How to Broadcast a Custom Message</h2>



To broadcast a custom message along with the standard&nbsp;<code>shutdown</code>&nbsp;notification type your message after the time argument.



The following example, will shut down the system in 30 minutes from now and notify the users that a hardware upgrade will be performed:



<pre class="wp-block-code"><code>sudo shutdown +30 "Hardware upgrade"</code></pre>



It is important to mention that when specifying a custom wall message, you must specify a time argument too.



<h2 id="how-to-reboot-the-system">How to Reboot the System</h2>



To reboot the system, use the&nbsp;<code>-r</code>&nbsp;argument:



<pre class="wp-block-code"><code>sudo shutdown -r</code></pre>



You can also specify a time argument and a custom message:



<pre class="wp-block-code"><code>shutdown -r +5 "Updating kernel"</code></pre>



The command above will reboot the system after 5 minutes and broadcast&nbsp;<code>Updating kernel</code>.



<h2 id="how-to-cancel-a-scheduled-shutdown">How to Cancel a Scheduled Shutdown</h2>



If you have scheduled shutdown and you want to cancel it, you can use the&nbsp;<code>-c</code>&nbsp;argument:



<pre class="wp-block-code"><code>sudo shutdown -c</code></pre>



When canceling a scheduled shutdown, you cannot specify a time argument, but you can still broadcast a message that will be sent to all users.



<pre class="wp-block-code"><code>sudo shutdown -c "Canceling the reboot"</code></pre>



<h2 id="conclusion">Conclusion</h2>



The&nbsp;<code>shutdown</code>&nbsp;command allows you to halt, power-off and reboot your Linux system.



To learn more about&nbsp;<code>shutdown</code>, visit the&nbsp;<a href="https://linux.die.net/man/8/shutdown" rel="noreferrer noopener" target="_blank">shutdown man</a>&nbsp;page.



If you have any questions or feedback, feel free to leave a comment.

In this tutorial, we will show you how to use the&nbsp;shutdown&nbsp;command through practical examples and detailed explanations of the most com...

Linux Shutdown Command - TCMHACK

Linux Shutdown Command

Let&rsquo;s Encrypt is a free SSL provider. Porkbun is very good domain registrar. We can download free SSL from porkbun dashboard. All we need is to upload it into our VPS server and need to add the path of the certificates into virtual host file.

Download SSL from porkbun.
You shall get a ZIP file containing the following 4 files:-

<ol>
<li>domain.cert.pem</li>
<li>intermediate.cert.pem</li>
<li>private.key.pem</li>
<li>public.key.pem</li>
</ol>

Now Upload file no. 1 and 3 only (i.e. domain.cert.pem and private.key.pem) into your VPS home folder (i.e. /home/admin/).

Create a Virtual Host for your domain (for example: yourdomain.com) as shown below:

<pre class="wp-block-code"><code>sudo nano /etc/nginx/sites-available/wbxpress.net.conf</code></pre>

<pre class="wp-block-code"><code>server {
 server_name yourdomain.com www.yourdomain.com;
 root /var/www/yourdomain;
 index index.html index.php;

 location / {
 try_files $uri $uri/ /index.php?$args;
 }

 location ~* \.php$ {
 fastcgi_pass unix:/run/php/php7.2-fpm.sock;
 include fastcgi_params;
 fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
 fastcgi_param SCRIPT_NAME $fastcgi_script_name;
 }

 listen 443 ssl http2;
 listen [::]:443 ssl http2;

 ssl_certificate /home/admin/domain.cert.pem;
 ssl_certificate_key /home/admin/private.key.pem;	
}
server {
 if ($host = www.yourdomain.com) {
 return 301 https://yourdomain.net$request_uri;
 }
 if ($host = yourdomain.com) {
 return 301 https://yourdomain.net$request_uri;
 }
 listen 80;
 listen [::]:80;
 server_name yourdomain.com www.yourdomain.com;
 return 404;
}</code></pre>

Also, we need to replace SSL settings as found from&nbsp;<a href="https://mozilla.github.io/server-side-tls/ssl-config-generator/" target="_blank" rel="noreferrer noopener">SSL Config File Generator</a>&nbsp;at nginx.conf file.

<pre class="wp-block-code"><code>sudo nano /etc/nginx/nginx.conf</code></pre>

<pre class="wp-block-preformatted">ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers 'ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS';
ssl_prefer_server_ciphers on;</pre>

The above configuration works perfectly well in our case.

Let’s Encrypt is a free SSL provider. Porkbun is very good domain registrar. We can download free SSL from porkbun dashboard. All we need is to u...

How to Install a Porkbun SSL on NGINX - TCMHACK

How to Install a Porkbun SSL on NGINX

In this tutorial we are going to show you, with step-by-step instructions on how to install Let&rsquo;s Encrypt with Apache on Ubuntu.

Let&rsquo;s Encrypt is an open SSL Certificate Authority (CA) that offers free domain-validated (DV) certificates for your websites. SSL Certificates are used to establish a secure encrypted connection between a web server and a user&rsquo;s web browser. The SSL certificates that have been issued by Let&rsquo;s Encrypt are valid for 90 days and are trusted by most web browsers today.

<h2>1. Requirements</h2>

In order to start with the installation procedure, you need to have Apache or Nginx installed on your server. If there is no web server installed on your virtual server, please follow this tutorial to install Apache.

Also, you need a registered domain name with its A record pointing to your server&rsquo;s IP address. For the purposes of this tutorial, we will use &lsquo;yourdomain.com&rsquo;.

<h2>2. Install CertBot</h2>

Run the following commands:

<pre class="wp-block-code"><code>sudo apt-get install software-properties-common python-software-properties
sudo add-apt-repository ppa:certbot/certbot
sudo apt-get update
sudo apt-get install python-certbot-apache</code></pre>

<h2>3. Install Let&rsquo;s Encrypt SSL</h2>

Install Let&rsquo;s Encrypt SSL certificate on your domain (do not forget to replace &lsquo;yourdomain.com&rsquo; with your actual domain):

<pre class="wp-block-code"><code>sudo certbot --apache -d yourdomain.com</code></pre>

<pre class="wp-block-preformatted">Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator apache, Installer apache
Enter email address (used for urgent renewal and security notices) (Enter 'c' to
cancel): admin@yourdomain.com

Please read the Terms of Service at
https://letsencrypt.org/documents/LE-SA-v1.2-November-15-2017.pdf. You must
agree in order to register with the ACME server at
https://acme-v01.api.letsencrypt.org/directory
(A)gree/(C)ancel: A

Would you be willing to share your email address with the Electronic Frontier
Foundation, a founding partner of the Let's Encrypt project and the non-profit
organization that develops Certbot? We'd like to send you email about EFF and
our work to encrypt the web, protect its users and defend digital rights.
(Y)es/(N)o: N
Obtaining a new certificate
Performing the following challenges:
tls-sni-01 challenge for linuxhostsupport.com
Waiting for verification&hellip;
Cleaning up challenges
Created an SSL vhost at /etc/apache2/sites-available/000-default-le-ssl.conf
Deploying Certificate for yourdomain.com to VirtualHost /etc/apache2/sites-available/000-default-le-ssl.conf
Enabling available site: /etc/apache2/sites-available/000-default-le-ssl.conf</pre>

<h2>4. Redirect HTTP traffic to HTTPS</h2>

<pre class="wp-block-preformatted">Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
1: No redirect - Make no further changes to the webserver configuration.
2: Redirect - Make all requests redirect to secure HTTPS access. Choose this for
new sites, or if you're confident your site works on HTTPS. You can undo this
change by editing your web server's configuration.
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
Redirecting vhost in /etc/apache2/sites-enabled/000-default.conf to ssl vhost in /etc/apache2/sites-available/000-default-le-ssl.conf

Congratulations! You have successfully enabled https://yourdomain.com</pre>

<h2>5. Renew the SSL certificate with a cron job</h2>

Create a cron job so the SSL certificate is renewed automatically. Run:

<pre class="wp-block-code"><code>crontab -e</code></pre>

and add the following line:

<pre class="wp-block-code"><code>0 0 1 * * /usr/bin/letsencrypt renew &gt;&gt; /var/log/letsencrypt-renew.log</code></pre>

Save and close that file and restart cron service for the changes to take effect:

<pre class="wp-block-code"><code>service cron restart</code></pre>

Open https://yourdomain.com in your favorite web browser, and check whether Let&rsquo;s Encrypt SSL is installed properly:

That is it. Let&rsquo;s Encrypt SSL certificate has been successfully installed on your website.

In this tutorial we are going to show you, with step-by-step instructions on how to install Let’s Encrypt with Apache on Ubuntu.



Let’s Encrypt...

How to install Let's Encrypt on Apache2 - TCMHACK

How to install Let's Encrypt on Apache2

Hey Guys, In this tutorial, we will learn how to upload files via ssh using terminal.

Uploading files via ssh required when you don't have any cPanel to work with like aws hosting which only provides you the SSH.

So we will be using the SCP (Secure Copy Protocal) for file transfer. Let's start.

<h3>What is Secure Copy Protocal (SCP)</h3>

Secure copy protocol (SCP) is a means of securely transferring computer files between a local host and a remote host or between two remote hosts.It is based on the Secure Shell (SSH) protocol.

"SCP" commonly refers to both the Secure Copy Protocol and the program itself. According to OpenSSH developers in April 2019 the scp protocol is outdated, inflexible and not readily fixed; they recommend the use of more modern protocols like sftp and rsync for file transfer.

The SCP program is a software tool implementing the SCP protocol as a service daemon or client. It is a program to perform secure copying.

<h4>Syntax</h4>

Typically, a syntax of&nbsp;scp&nbsp;program&nbsp;is like the syntax of&nbsp;cp&nbsp;(copy):

Copying file to host:

<pre class="wp-block-code"><code>scp SourceFile user@host:directory/TargetFile</code></pre>

Copying folder from host:

<pre class="wp-block-code"><code>scp user@host:directory/SourceFile TargetFile
scp -r user@host:directory/SourceFolder TargetFolder</code></pre>

Note that if the remote host uses a port other than the default of 22, it can be specified in the command. For example, copying a file from host:

<pre class="wp-block-code"><code>scp -P 2222 user@host:directory/SourceFile TargetFile</code></pre>

If you're working with aws hosting then you must have to use the key

<pre class="wp-block-code"><code>scp -i yourkey.pem user@host:directory/SourceFile TargetFile</code></pre>

Let's take an example:

<pre class="wp-block-code"><code>scp -i mykey.pem /var/www/html/myfile.sql ubuntu@google.com:/var/www/htmlmyfile.sql</code></pre>

<h4>Feels like watching?</h4>
<iframe style="width: 678px; height: 381px;" title="YouTube video player" src="https://www.youtube.com/embed/C0ImnCTI1W8?si=2ZMlGpmugDBo_Qrc" width="678" height="381" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen="allowfullscreen" referrerpolicy="strict-origin-when-cross-origin"></iframe>

Hey Guys, In this tutorial, we will learn how to upload files via ssh using terminal.



Uploading files via ssh required when you don't have any...

How to upload files via ssh using scp on ubuntu - TCMHACK

How to upload files via ssh using scp on ubuntu

Today we're going to deploy a website to the google firebase. Google firebase is free &amp; easy to use. Google firebase provides the free hosting upto 1GB space, if you need more there are some plans provided by firebase. You can use as per your requirements.

Before starting, I assume you already have a google firebase account and a website ready to be host.

let's start hosting a website to google firebase.

<h3>1. Create a Build</h3>

Open cmd prompt in your website folder and run the below command

<pre class="wp-block-code"><code>npm run build</code></pre>

It will create a build folder which contains all the website data ready to be host. All website data means html, js, css, images files.
<img src="../../../../uploads/1744736389804-create-build-1024x516.png" alt="" width="1024" height="516">

<h3>2. Create Project in Firebase</h3>

Login to your Firebase Console &amp; add a new project. If you have already created a project, just choose that.
<img src="../../../../uploads/1744736425550-add-new-project-in-firebase-1024x470.png" alt="" width="1024" height="470">

<h3>3. Open Hosting Page</h3>

You can find a Hosting link in the left side menu. Click on it and open the hosting page.
<img src="../../../../uploads/1744736456047-here.png" alt="" width="960" height="439">

<h3>4. Set up firebase hosting.</h3>

Open cmd in your project folder and install the Firebase CLI into website.

<h4>1. Install Firebse CLI</h4>

<pre class="wp-block-code"><code>npm install -g firebase-tools</code></pre>

<h3><img src="../../../../uploads/1744736520931-firebase-installation-1024x240.png" alt="" width="1024" height="240"></h3>
<h4>2.&nbsp;Initialize the Project</h4>

Open a terminal window and navigate to or create a root directory for your web app

<h5>A. Sign in to Google</h5>

It will take you to Google Login page and log you in into the app.

<pre class="wp-block-code"><code>firebase login</code></pre>

<h5>B. Initiate your project</h5>

<pre class="wp-block-code"><code>firebase init</code></pre>

<ul>
<li>Go to hosting by up-down arrow key</li>
<li>Select Hosting by clicking the space button on keyboard and hit Enter</li>
<li>It will ask you to select the hosting folder, write build</li>
<li>Next Configure as a single-page app, write Y</li>
<li>Next Overwrite the index.html, write N</li>
<li>Firebase initialisation is complete. Now, deploy the website in next step.</li>
</ul>
<img src="../../../../uploads/1744736581454-firebase-initialisation-1024x517.png" alt="" width="1024" height="517">

<h4>3. Deploy to Firebase Hosting</h4>

Run this command from your app&rsquo;s root directory:

<pre class="wp-block-code"><code>firebase deploy</code></pre>

<h3><img src="../../../../uploads/1744736632941-firebase-deployemnt-1024x309.png" alt="" width="1024" height="309"></h3>
<h4>4. Open and run your website.</h4>

After successful deployment, firebase will provide you a link and you can use it to see your live website in action.

This link will be a subdomain of google domains. It will be look like your-project-id.web.app

If you want to add your custom domain to this website, you can follow the link <a href="../../../../blog/google-firebase-custom-domain-subdomain-mapping-with-godaddy">Map custom domain to firebase hosting.</a>

Have any questions? Write into the comment section.

Today we're going to deploy a website to the google firebase. Google firebase is free &amp; easy to use. Google firebase provides the free hostin...

How to deploy websites to Google Firebase - TCMHACK

How to deploy websites to Google Firebase

In my post about&nbsp;<a href="../../../../blog/how-to-deploy-websites-to-google-firebase">how to deploy your website on firebase</a>, I explained about hosting our website on Google Firebase and we are able to access the website using the firebase Url. Now in this article, we are going to talk and learn about adding our website with custom domain like your own domains purchased on the domain providing websites like&nbsp;<a href="https://www.godaddy.com/" target="_blank" rel="noreferrer noopener" aria-label=" (opens in a new tab)">GoDaddy</a>&nbsp;and&nbsp;<a href="https://www.namecheap.com/" target="_blank" rel="noreferrer noopener" aria-label=" (opens in a new tab)">NameCheap</a>. I this article we are going to integrate our domain in GoDaddy with Firebase hosted website. I tried and Integrated my custom domain by taking reference from&nbsp;<a href="https://firebase.google.com/docs/hosting/custom-domain" target="_blank" rel="noreferrer noopener" aria-label=" (opens in a new tab)">google firebase documentation</a>.

Let's Start the Domain/Subdomain Mapping.

<ol>
<li>Go to firebase console and check your project. <img src="../../../../uploads/1744736975467-firebase-project-overview-console-page-1024x447.png" alt="" width="1024" height="447"></li>
<li>Check your hosted site Click&nbsp;Hosting&nbsp;Link from the left side and you can see your default website deployed <img src="../../../../uploads/1744737058809-firebase-web-hosting-project-page-1024x284.png" alt="" width="1024" height="284"></li>
<li style="font-weight: bold;">Click Connect Domain link from the page.</li>
<li>Add Domain Name Add Domain name in the connect custom domain popup <img src="../../../../uploads/1744737126386-add-domain-name-in-customdomain-1-1024x621.png" alt="" width="1024" height="621"></li>
<li>Get Google Site Verification Code Now you will get the google site verification ID and Copy the Id Note: Do not copy the only value, you should copy the whole text like 
<pre>google-site-verification=9xUIjWlRgKX-jsM8Hhlaj3HHtDK0xnEoA98Ms </pre>
We need this google site verification Id to add to&nbsp;TXT record in DNS provider. <img src="../../../../uploads/1744737265680-verify-ownership-verification-customdomain-1024x583.png" alt="" width="1024" height="583"></li>
<li>Login to Godaday account Now go back to GoDaddy and login to your account and go to&nbsp;<a href="https://dcc.godaddy.com/domains/" target="_blank" rel="noreferrer noopener">Domain Page</a></li>
<li>Go to Manage DNS Now click on the three dots near to&nbsp;Use My Domain&nbsp;button and click&nbsp;Manage DNS link <img src="../../../../uploads/1744737338952-godaddy-manage-domain-dns-1024x663.png" alt="" width="1024" height="663"></li>
<li>Add Google Site Varification Code On manage DNS page add the value of google site verification Id as TXT value in the list <img src="../../../../uploads/1744737408772-txt-value-for-google-verification-1024x64.png" alt="" width="1024" height="64"></li>
<li>Verify Domain Mapping Now after adding this&nbsp;TXT value in the DNS list, Go back to firebase console and click the verify link from the custom domain popup</li>
<li>Get IP address of hosted site In FireBase on GoOnline Step you will get 2 IP address which you need to add in the GoDaddy DNS table again as&nbsp;Type A value <img src="../../../../uploads/1744737496213-typea-value-update-in-dns-table-1024x275.png" alt="" width="1024" height="275"></li>
</ol>

<pre class="wp-block-preformatted">&nbsp;</pre>

<blockquote class="wp-block-quote">
Use @ if you want to map the domain and subdomain for subdomain.
Example: @ will be refered as: http://www.mydomain.com and subdomain will be refered as http://subdomain.mydomain.com
</blockquote>

11. Now go back to Firebase console again and Connect.

After performing all the steps in some time, you can see your website is up and running with the custom domain you just added in the firebase. You will see certificate error for HTTP for some time but after some time with certificate verification, the error will go and you can access website in HTTPS.

Above steps, I used to connect my custom domain with GoDaddy and It worked for me. I wrote this article because I didn&rsquo;t find any recently updated article on the internet about the whole process.

Please feel free to write me incase you face issues while connecting your custom domain.

Learn how to map a custom domain or subdomain from GoDaddy to your Google Firebase project with step-by-step instructions and best practices.

Google Firebase custom domain/subdomain mapping with GoDaddy - TCMHACK

Google Firebase custom domain/subdomain mapping with GoDaddy

<h3 id="introduction">Introduction</h3>



Redis is an in-memory key-value store known for its flexibility, performance, and wide language support. In this guide, we will demonstrate how to install and configure Redis on an Ubuntu 16.04 server.



<h2 id="prerequisites">Prerequisites</h2>



To complete this guide, you will need access to an Ubuntu 16.04 server. You will need a non-root user with <code>sudo</code> privileges to perform the administrative functions required for this process. You can learn how to set up an account with these privileges by following our <a href="https://www.digitalocean.com/community/tutorials/initial-server-setup-with-ubuntu-16-04">Ubuntu 16.04 initial server setup guide</a>.



When you are ready to begin, log in to your Ubuntu 16.04 server with your&nbsp;<code>sudo</code>&nbsp;user and continue below.



<h2 id="install-the-build-and-test-dependencies">Install the Build and Test Dependencies</h2>



In order to get the latest version of Redis, we will be compiling and installing the software from source. Before we download the code, we need to satisfy the build dependencies so that we can compile the software.



To do this, we can install the&nbsp;<code>build-essential</code>&nbsp;meta-package from the Ubuntu repositories. We will also be downloading the&nbsp;<code>tcl</code>&nbsp;package, which we can use to test our binaries.



We can update our local&nbsp;<code>apt</code>&nbsp;package cache and install the dependencies by typing:



<pre class="wp-block-preformatted">sudo apt-get update
sudo apt-get install build-essential tcl
</pre>



<h2 id="download-compile-and-install-redis">Download, Compile, and Install Redis</h2>



Next, we can begin to build Redis.



<h3 id="download-and-extract-the-source-code">Download and Extract the Source Code</h3>



Since we won’t need to keep the source code that we’ll compile long term (we can always re-download it), we will build in the&nbsp;<code>/tmp</code>&nbsp;directory. Let’s move there now:



<pre class="wp-block-preformatted">cd /tmp
</pre>



Now, download the latest stable version of Redis. This is always available at <a href="http://download.redis.io/redis-stable.tar.gz" target="_blank" rel="noreferrer noopener" aria-label=" (opens in a new tab)">a stable download URL</a>:



<pre class="wp-block-preformatted">curl -O http://download.redis.io/redis-stable.tar.gz
</pre>



Unpack the tarball by typing:



<pre class="wp-block-preformatted">tar xzvf redis-stable.tar.gz
</pre>



Move into the Redis source directory structure that was just extracted:



<pre class="wp-block-preformatted">cd redis-stable
</pre>



<h3 id="build-and-install-redis">Build and Install Redis</h3>



Now, we can compile the Redis binaries by typing:



<pre class="wp-block-preformatted">make
</pre>



After the binaries are compiled, run the test suite to make sure everything was built correctly. You can do this by typing:



<pre class="wp-block-preformatted">make test
</pre>



This will typically take a few minutes to run. Once it is complete, you can install the binaries onto the system by typing:



<pre class="wp-block-preformatted">sudo make install
</pre>



<h2 id="configure-redis">Configure Redis</h2>



Now that Redis is installed, we can begin to configure it.



To start off, we need to create a configuration directory. We will use the conventional&nbsp;<code>/etc/redis</code>&nbsp;directory, which can be created by typing:



<pre class="wp-block-preformatted">sudo mkdir /etc/redis
</pre>



Now, copy over the sample Redis configuration file included in the Redis source archive:



<pre class="wp-block-preformatted">sudo cp /tmp/redis-stable/redis.conf /etc/redis
</pre>



Next, we can open the file to adjust a few items in the configuration:



<pre class="wp-block-preformatted">sudo nano /etc/redis/redis.conf
</pre>



In the file, find the&nbsp;<code>supervised</code>&nbsp;directive. Currently, this is set to&nbsp;<code>no</code>. Since we are running an operating system that uses the systemd init system, we can change this to&nbsp;<code>systemd</code>:/etc/redis/redis.conf



<pre class="wp-block-code"><code>. . .

# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
# supervised no - no supervision interaction
# supervised upstart - signal upstart by putting Redis into SIGSTOP mode
# supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
# supervised auto - detect upstart or systemd method based on
# UPSTART_JOB or NOTIFY_SOCKET environment variables
# Note: these supervision methods only signal "process is ready."
# They do not enable continuous liveness pings back to your supervisor.
supervised systemd

. . .</code></pre>



Next, find the&nbsp;<code>dir</code>&nbsp;directory. This option specifies the directory that Redis will use to dump persistent data. We need to pick a location that Redis will have write permission and that isn’t viewable by normal users.



We will use the&nbsp;<code>/var/lib/redis</code>&nbsp;directory for this, which we will create in a moment:/etc/redis/redis.conf



<pre class="wp-block-code"><code>. . .

# The working directory.
#
# The DB will be written inside this directory, with the filename specified
# above using the 'dbfilename' configuration directive.
#
# The Append Only File will also be created inside this directory.
#
# Note that you must specify a directory here, not a file name.
dir /var/lib/redis

. . .</code></pre>



Save and close the file when you are finished.



<h2 id="create-a-redis-systemd-unit-file">Create a Redis systemd Unit File</h2>



Next, we can create a systemd unit file so that the init system can manage the Redis process.



Create and open the&nbsp;<code>/etc/systemd/system/redis.service</code>&nbsp;file to get started:



<pre class="wp-block-preformatted">sudo nano /etc/systemd/system/redis.service
</pre>



Inside, we can begin the&nbsp;<code>[Unit]</code>&nbsp;section by adding a description and defining a requirement that networking be available before starting this service:/etc/systemd/system/redis.service



<pre class="wp-block-code"><code>[Unit]
Description=Redis In-Memory Data Store
After=network.target</code></pre>



In the&nbsp;<code>[Service]</code>&nbsp;section, we need to specify the service’s behavior. For security purposes, we should not run our service as&nbsp;<code>root</code>. We should use a dedicated user and group, which we will call&nbsp;<code>redis</code>&nbsp;for simplicity. We will create these momentarily.



To start the service, we just need to call the&nbsp;<code>redis-server</code>&nbsp;binary, pointed at our configuration. To stop it, we can use the Redis&nbsp;<code>shutdown</code>&nbsp;command, which can be executed with the&nbsp;<code>redis-cli</code>&nbsp;binary. Also, since we want Redis to recover from failures when possible, we will set the&nbsp;<code>Restart</code>&nbsp;directive to “always”:/etc/systemd/system/redis.service



<pre class="wp-block-code"><code>[Unit]
Description=Redis In-Memory Data Store
After=network.target

[Service]
User=redis
Group=redis
ExecStart=/usr/local/bin/redis-server /etc/redis/redis.conf
ExecStop=/usr/local/bin/redis-cli shutdown
Restart=always</code></pre>



Finally, in the&nbsp;<code>[Install]</code>&nbsp;section, we can define the systemd target that the service should attach to if enabled (configured to start at boot):/etc/systemd/system/redis.service



<pre class="wp-block-code"><code>[Unit]
Description=Redis In-Memory Data Store
After=network.target

[Service]
User=redis
Group=redis
ExecStart=/usr/local/bin/redis-server /etc/redis/redis.conf
ExecStop=/usr/local/bin/redis-cli shutdown
Restart=always

[Install]
WantedBy=multi-user.target</code></pre>



Save and close the file when you are finished.



<h2 id="create-the-redis-user-group-and-directories">Create the Redis User, Group and Directories</h2>



Now, we just have to create the user, group, and directory that we referenced in the previous two files.



Begin by creating the&nbsp;<code>redis</code>&nbsp;user and group. This can be done in a single command by typing:



<pre class="wp-block-preformatted">sudo adduser --system --group --no-create-home redis
</pre>



Now, we can create the&nbsp;<code>/var/lib/redis</code>&nbsp;directory by typing:



<pre class="wp-block-preformatted">sudo mkdir /var/lib/redis
</pre>



We should give the&nbsp;<code>redis</code>&nbsp;user and group ownership over this directory:



<pre class="wp-block-preformatted">sudo chown redis:redis /var/lib/redis
</pre>



Adjust the permissions so that regular users cannot access this location:



<pre class="wp-block-preformatted">sudo chmod 770 /var/lib/redis
</pre>



<h2 id="start-and-test-redis">Start and Test Redis</h2>



Now, we are ready to start the Redis server.



<h3 id="start-the-redis-service">Start the Redis Service</h3>



Start up the systemd service by typing:



<pre class="wp-block-preformatted">sudo systemctl start redis
</pre>



Check that the service had no errors by running:



<pre class="wp-block-preformatted">sudo systemctl status redis
</pre>



You should see something that looks like this:



<pre class="wp-block-code"><code>Output● redis.service - Redis Server
 Loaded: loaded (/etc/systemd/system/redis.service; enabled; vendor preset: enabled)
 Active: active (running) since Wed 2016-05-11 14:38:08 EDT; 1min 43s ago
 Process: 3115 ExecStop=/usr/local/bin/redis-cli shutdown (code=exited, status=0/SUCCESS)
 Main PID: 3124 (redis-server)
 Tasks: 3 (limit: 512)
 Memory: 864.0K
 CPU: 179ms
 CGroup: /system.slice/redis.service
 └─3124 /usr/local/bin/redis-server 127.0.0.1:6379 

. . .</code></pre>



<h3 id="test-the-redis-instance-functionality">Test the Redis Instance Functionality</h3>



To test that your service is functioning correctly, connect to the Redis server with the command-line client:



<pre class="wp-block-preformatted">redis-cli
</pre>



In the prompt that follows, test connectivity by typing:



<pre class="wp-block-preformatted">127.0.0.1:6379> ping</pre>



You should see:



<pre class="wp-block-code"><code>Output: PONG</code></pre>



Check that you can set keys by typing:



<pre class="wp-block-preformatted">127.0.0.1:6379> set test "It's working!" </pre>



<pre class="wp-block-code"><code>Output: OK</code></pre>



Now, retrieve the value by typing:



<pre class="wp-block-preformatted">127.0.0.1:6379> get test</pre>



You should be able to retrieve the value we stored:



<pre class="wp-block-code"><code>Output: "It's working!"</code></pre>



Exit the Redis prompt to get back to the shell:



<pre class="wp-block-preformatted">127.0.0.1:6379> exit </pre>



As a final test, let’s restart the Redis instance:



<pre class="wp-block-preformatted">sudo systemctl restart redis
</pre>



Now, connect with the client again and confirm that your test value is still available:



<pre class="wp-block-preformatted">redis-cli
</pre>



<pre class="wp-block-preformatted">127.0.0.1:6379> get test </pre>



The value of your key should still be accessible:



<pre class="wp-block-code"><code>Output: "It's working!"</code></pre>



Back out into the shell again when you are finished:



<pre class="wp-block-preformatted">127.0.0.1:6379> exit </pre>



<h3 id="enable-redis-to-start-at-boot">Enable Redis to Start at Boot</h3>



If all of your tests worked, and you would like to start Redis automatically when your server boots, you can enable the systemd service.



To do so, type:



<pre class="wp-block-preformatted">sudo systemctl enable redis
</pre>



<pre class="wp-block-code"><code>OutputCreated symlink from /etc/systemd/system/multi-user.target.wants/redis.service to /etc/systemd/system/redis.service.</code></pre>

Introduction



Redis is an in-memory key-value store known for its flexibility, performance, and wide language support. In this guide, we will d...