https://lead-devops.blackdevhub.online/en/tags/processes/Recent content in Processes on Lead DevOpsHugoen-USFri, 04 Sep 2026 00:00:00 +0000https://lead-devops.blackdevhub.online/en/posts/lsof-port-file-processes/Fri, 04 Sep 2026 00:00:00 +0000https://lead-devops.blackdevhub.online/en/posts/lsof-port-file-processes/<p>Service won&rsquo;t start — port 8080 is already bound. You dig into who&rsquo;s holding it, and discover the same process has your config file open while you&rsquo;re trying to edit it. lsof answers both questions: which processes opened which files and sockets.</p> <h2 id="listening-ports">Listening Ports </h2> <p>The classic task — find who is listening on a specific port.</p> <div class="td-code td-code--untitled" id="td-code-9cff1145-fence-0" data-td-code data-td-code-auto-id data-td-language="bash" data-td-line-count="1"> <div class="td-code__viewport" id="td-code-9cff1145-fence-0-viewport" data-td-code-viewport><div class="highlight"><pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="line"><span class="cl">lsof -i -n -P</span></span></code></pre></div></div> </div> <div class="td-table-scroll td-table-scroll--static"> <table> <thead> <tr> <th scope="col">Flag</th> <th scope="col">Effect</th> </tr> </thead> <tbody> <tr> <td><code>-i</code></td> <td>Show internet sockets</td> </tr> <tr> <td><code>-n</code></td> <td>Skip DNS resolution (show IP instead of hostname)</td> </tr> <tr> <td><code>-P</code></td> <td>Skip port-to-service conversion (show 80 instead of http)</td> </tr> </tbody> </table> </div> <p>Without <code>-n -P</code>, lsof wastes time on DNS lookups and resolves ports through /etc/services. On production hosts that&rsquo;s unnecessary seconds.</p>