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@@ -934,6 +934,11 @@ <h3>Additional Flags and their Functionalities:</h3>
 <td align="left">Like <code>-l</code> but without showing group</td>
 </tr>
 <tr>
+<td align="left"><code>-C</code></td>
+<td align="left"><center>-</center></td>
+<td align="left">List entries by columns</td>
+</tr>
+<tr>
 <td align="left"><center>-</center></td>
 <td align="left"><code>--group-directories-first</code></td>
 <td align="left">List directories before files</td>
@@ -1619,19 +1624,40 @@ <h3>Additional Flags and their Functionalities</h3>
 <p>Syntax:</p>
 <pre><code class="language- hljs " data-lang="">tail [OPTION] [FILENAME]
 </code></pre>
-<h3>Get a specific number of lines with <code>tail</code>:</h3>
-<p>Use the <code>-n</code> option with a number(should be an integer) of lines to display.</p>
+<h2>Common Use Cases</h2>
+<h3>Get a specific number of lines:</h3>
+<p>Use the <code>-n</code> option with a number (should be an integer) of lines to display.</p>
 <p>Example:</p>
 <pre><code class="language- hljs " data-lang="">tail -n 10 foo.txt
 </code></pre>
 <p>This command will display the last ten lines of the file <code>foo.txt</code>.</p>
-<h3>Refresh the output on any new entry in a file</h3>
+<h3>Monitor new entry on files in real-time</h3>
 <p>It is possible to let tail output any new line added to the file you are looking into. So, if a new line is written to the file, it will immediately be shown in your output. This can be done using the <code>--follow</code> or <code>-f</code> option. This is especially useful for monitoring log files.</p>
 <p>Example:</p>
 <pre><code class="language- hljs " data-lang="">tail -f foo.txt
 </code></pre>
-<p>Syntax:</p>
-<pre><code class="language-xml hljs xml" data-lang="xml">tail -n <span class="hljs-tag">&lt;<span class="hljs-name">number</span>&gt;</span> foo.txt
+<p>Press <code>Ctrl+C</code> to stop following.</p>
+<h3>Combine options for log monitoring</h3>
+<pre><code class="language-php hljs php" data-lang="php">tail -n <span class="hljs-number">100</span> -f app.log      <span class="hljs-comment"># Show last 100 lines, then follow</span>
+tail -f -s <span class="hljs-number">2</span> slow.log       <span class="hljs-comment"># Follow with 2-second refresh interval</span>
+</code></pre>
+<h3>Follow multiple files simultaneously</h3>
+<pre><code class="language-php hljs php" data-lang="php">tail -f /<span class="hljs-keyword">var</span>/log/nginx/access.log /<span class="hljs-keyword">var</span>/log/nginx/error.log
+</code></pre>
+<h3>Display specific byte ranges</h3>
+<pre><code class="language-php hljs php" data-lang="php">tail -c <span class="hljs-number">100</span> file.txt        <span class="hljs-comment"># Last 100 bytes</span>
+tail -c +<span class="hljs-number">50</span> file.txt        <span class="hljs-comment"># From byte 50 to end</span>
+</code></pre>
+<h3>Follow logs even after rotation</h3>
+<pre><code class="language-php hljs php" data-lang="php">tail -F /<span class="hljs-keyword">var</span>/log/app.log
+</code></pre>
+<p>The <code>-F</code> option is crucial for monitoring logs managed by logrotate.</p>
+<h3>Skip header lines</h3>
+<pre><code class="language-php hljs php" data-lang="php">tail -n +<span class="hljs-number">2</span> data.csv         <span class="hljs-comment"># Start from line 2 (skip header)</span>
+tail -n +<span class="hljs-number">11</span> file.txt        <span class="hljs-comment"># Start from line 11 onwards</span>
+</code></pre>
+<h3>Quiet mode for multiple files</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">tail -q -n 5 *.<span class="hljs-built_in">log</span>          <span class="hljs-comment"># No filename headers</span>
 </code></pre>
 <h3>Additional Flags and their Functionalities</h3>
 <table>
@@ -1679,7 +1705,7 @@ <h3>Additional Flags and their Functionalities</h3>
 <td align="left">Never output headers giving file names</td>
 </tr>
 <tr>
-<td align="left">``</td>
+<td align="left"></td>
 <td align="left"><code>--retry</code></td>
 <td align="left">keep trying to open a file if it is inaccessible</td>
 </tr>
@@ -1710,6 +1736,13 @@ <h3>Additional Flags and their Functionalities</h3>
 </tr>
 </tbody>
 </table>
+<h2>Tips</h2>
+<ul>
+<li>Use <code>-F</code> instead of <code>-f</code> for production log monitoring</li>
+<li>Combine with <code>grep</code>, <code>awk</code>, or <code>sed</code> for filtered monitoring</li>
+<li>For large files, <code>tail</code> is much faster than opening in an editor</li>
+<li>Use <code>-n +N</code> to start from a specific line (useful for skipping headers)</li>
+</ul>
 <div style="page-break-after: always;"></div><h1>The <code>pwd</code> command</h1>
 <p>The <code>pwd</code> stands for Print Working Directory. It prints the path of the current working directory, starting from the root.</p>
 <p>Example:</p>
@@ -19543,6 +19576,205 @@ <h2>Important Notes</h2>
 </ul>
 <p>The <code>cfdisk</code> command provides an excellent balance between ease of use and functionality for disk partitioning tasks.</p>
 <p>For more details, check the manual: <code>man cfdisk</code></p>
+<div style="page-break-after: always;"></div><h1>The ifplugstatus Command</h1>
+<p>The <code>ifplugstatus</code> command is a diagnostic utility used to check the <strong>physical link status</strong> of network interfaces on Linux systems. It reports whether an interface (such as eth0, enp0s3, or wlan0) has a network cable connected or not. This tool is particularly useful for troubleshooting wired network connectivity and detecting unplugged cables.</p>
+<h2>Syntax</h2>
+<pre><code class="language-bash hljs bash" data-lang="bash">ifplugstatus [options] [interface]
+</code></pre>
+<h3>Parameters</h3>
+<ul>
+<li>
+<p>interface — the network interface to check (e.g., eth0, enp0s3, wlan0).</p>
+</li>
+<li>
+<p>options — optional flags for customizing output.</p>
+</li>
+</ul>
+<h2>Installation</h2>
+<p><code>ifplugstatus</code> is part of the <code>ifplugd</code> package.
+It can be installed using the following commands depending on your distribution:</p>
+<pre><code class="language-bash hljs bash" data-lang="bash"><span class="hljs-comment"># Ubuntu/Debian</span>
+sudo apt update
+sudo apt install ifplugd
+
+<span class="hljs-comment"># CentOS/RHEL/Fedora</span>
+sudo yum install ifplugd
+<span class="hljs-comment"># or</span>
+sudo dnf install ifplugd
+</code></pre>
+<h3>To verify installation:</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash"><span class="hljs-built_in">which</span> ifplugstatus
+</code></pre>
+<h2>Basic Usage</h2>
+<h3>1. Check the status of a single interface</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">ifplugstatus eth0
+</code></pre>
+<h3>Sample Output:</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">eth0: link beat detected
+</code></pre>
+<h3>or</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">eth0: link beat not detected
+</code></pre>
+<h3>Explanation:</h3>
+<ul>
+<li>
+<p>link beat detected → cable is plugged in and active.</p>
+</li>
+<li>
+<p>link beat not detected → cable is unplugged or inactive.
+<em>Note: 'link beat' is a legacy term from older Ethernet (10/100 Mbps). Modern Gigabit or higher interfaces may use different link detection signals, but the command generally reports an active physical link.</em></p>
+</li>
+</ul>
+<h3>2. Check multiple interfaces</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">ifplugstatus eth0 wlan0
+</code></pre>
+<h3>Sample Output:</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">eth0: link beat detected
+wlan0: link beat not detected
+</code></pre>
+<p>This allows quick verification of all available interfaces.</p>
+<h2>Options</h2>
+<p>Some popular option flags include:</p>
+<table>
+<thead>
+<tr>
+<th>Option</th>
+<th>Description</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td><code>-a</code></td>
+<td>Show all interfaces (default behavior).</td>
+</tr>
+<tr>
+<td><code>-i</code></td>
+<td>Specify a particular interface.</td>
+</tr>
+<tr>
+<td><code>-s</code></td>
+<td>Display a short summary only.</td>
+</tr>
+<tr>
+<td><code>-v</code></td>
+<td>Verbose output with more details.</td>
+</tr>
+<tr>
+<td><code>-q</code></td>
+<td>Quiet mode — minimal output.</td>
+</tr>
+<tr>
+<td><code>-h</code></td>
+<td>Display help information.</td>
+</tr>
+</tbody>
+</table>
+<h2>Practical Examples</h2>
+<h3>1. Check if the main Ethernet interface is connected</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">ifplugstatus eth0
+</code></pre>
+<p>Displays the current cable connection status for eth0.</p>
+<h3>2. Check all available network interfaces</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">ifplugstatus -a
+</code></pre>
+<p>Lists link status for every detected interface.</p>
+<h3>3. Use verbose mode for detailed results</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">ifplugstatus -v eth0
+</code></pre>
+<p>Provides more descriptive information about the link state.</p>
+<h3>4. Quiet mode for scripting or automation</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">ifplugstatus -q eth0
+</code></pre>
+<p>Outputs only the essential information, suitable for shell scripts.</p>
+<h2>Understanding the Output</h2>
+<p>A typical output may look like this:</p>
+<pre><code class="language-bash hljs bash" data-lang="bash">eth0: link beat detected
+enp0s3: link beat not detected
+</code></pre>
+<ul>
+<li>
+<p>Interface Name: eth0, enp0s3, etc.</p>
+</li>
+<li>
+<p>Link Status: Indicates whether a physical link (cable or signal) is present.</p>
+</li>
+</ul>
+<p>When integrated into scripts, this helps automate detection of disconnected interfaces or faulty cabling.</p>
+<h2>Common Use Cases</h2>
+<h3>1. Cable Connectivity Testing</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">ifplugstatus eth0
+</code></pre>
+<p>Quickly verify if a cable is physically connected to the network port.</p>
+<h3>2. Multi-Interface Monitoring</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">ifplugstatus eth0 wlan0
+</code></pre>
+<p>Check multiple interfaces simultaneously for link activity.</p>
+<h3>3. Continuous Monitoring</h3>
+<pre><code class="language-bash hljs bash" data-lang="bash">watch -n 5 ifplugstatus eth0
+</code></pre>
+<p>Updates the interface status every 5 seconds for real-time link monitoring.</p>
+<h2>Troubleshooting Common Issues</h2>
+<h3>1. Interface Not Found</h3>
+<p>If an incorrect interface name is given:</p>
+<pre><code class="language-bash hljs bash" data-lang="bash">eth5: No such device
+</code></pre>
+<p><strong>Fix:</strong> Use the ip a or ifconfig command to list valid interfaces.</p>
+<h3>2. Permission Denied</h3>
+<p>Some systems may require elevated privileges:</p>
+<pre><code class="language-bash hljs bash" data-lang="bash">sudo ifplugstatus eth0
+</code></pre>
+<h3>3. Command Not Found</h3>
+<p>If the command is missing:</p>
+<pre><code class="language-bash hljs bash" data-lang="bash"> ifplugstatus: <span class="hljs-built_in">command</span> not found
+</code></pre>
+<p><strong>Fix:</strong> Install the ifplugd package using your package manager.</p>
+<p><strong>Tip:</strong> Always ensure the ifplugd package is installed and your user has permission to access network interfaces.</p>
+<h2>Related Commands</h2>
+<table>
+<thead>
+<tr>
+<th>Command</th>
+<th>Description</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td><code>ip a</code> (preferred) / <code>ifconfig</code></td>
+<td>Display all network interfaces and details. <code>ip a</code> is the modern tool; <code>ifconfig</code> is legacy.</td>
+</tr>
+<tr>
+<td><code>ethtool eth0</code></td>
+<td>Retrieve advanced information about the network interface.</td>
+</tr>
+<tr>
+<td><code>nmcli device status</code></td>
+<td>Check connection status via NetworkManager.</td>
+</tr>
+<tr>
+<td><code>ping</code></td>
+<td>Test network reachability after confirming cable connection.</td>
+</tr>
+</tbody>
+</table>
+<h2>Important Notes</h2>
+<ul>
+<li>
+<p>Works best with wired Ethernet interfaces.</p>
+</li>
+<li>
+<p>Wireless interfaces may not always report link status accurately.</p>
+</li>
+<li>
+<p>The tool is read-only — it does not modify system settings.</p>
+</li>
+<li>
+<p>Lightweight and safe for use in both desktop and server environments.</p>
+</li>
+</ul>
+<h2>Manual Reference</h2>
+<p>For additional information and advanced usage:</p>
+<pre><code class="language-bash hljs bash" data-lang="bash">man ifplugstatus
+</code></pre>
 <div style="page-break-after: always;"></div><h1>Conclusion</h1>
 <p>Congratulations! You've reached the end of the <strong>101 Linux Commands eBook</strong>. Throughout this journey, you've explored over 135 essential Linux commands that form the foundation of system administration, development, and everyday Linux usage.</p>
 <h2>What You've Learned</h2>