Troubleshooting

Introduction to Troubleshooting Connection Issues

When working with Linux, connection issues can arise due to various reasons such as misconfigured DNS settings, firewall rules, or network interface configurations. I’ve seen this go wrong when a simple DNS misconfiguration can bring down an entire application. To troubleshoot these issues, Linux provides a range of tools, including resolvectl and ss. In this article, we will explore how to use these tools to diagnose and resolve common connection problems.

Introduction to Disk Usage Issues

I’ve seen disk usage issues plague even the most well-maintained Linux systems, often due to duplicate files and unnecessary logs. As of 2026, both Btrfs and Ext4 filesystems are widely used, each with their own set of tools and best practices for troubleshooting and resolving these issues. In this article, we’ll delve into practical steps for identifying and addressing duplicate files and unnecessary logs on both Btrfs and Ext4 filesystems, focusing on current tools and methodologies.

Introduction to Emergency Mode

I’ve seen this go wrong when a Linux system encounters a critical issue during boot - it may enter Emergency Mode. This mode provides a minimal environment for troubleshooting and recovery. With many Linux distributions, including Debian and Arch Linux, updating their boot processes to use systemd, understanding how to rescue a system stuck in Emergency Mode is crucial.

Identifying the Issue

To rescue a system in Emergency Mode, you first need to identify the cause of the issue. Don’t bother with guessing - check the system logs, which are usually available in the /var/log directory. I usually start with the journalctl command to view the system logs:

Introduction to Troubleshooting Failed Mounts

When I’m dealing with a Linux system that won’t boot properly, one of the first things I check is the mount points. systemd and the /etc/fstab file are crucial in this process, but issues can still arise, leading to failed mounts and potential system instability. In this article, I’ll walk you through practical steps to troubleshoot and resolve failed mounts at boot time, focusing on systemd and fstab configurations.

Introduction to Emergency Mode

I’ve seen this go wrong when a Linux system encounters a critical issue during boot - it can be a real headache. But, thankfully, Linux has a built-in safety net called emergency mode. This mode kicks in when there’s a failed filesystem check or an inability to mount a necessary partition, providing a minimal environment for troubleshooting and repair. With the advancements in Linux, understanding how to use emergency mode is crucial for system administrators and users alike.

Introduction to Troubleshooting Slow DNS Lookups

I’ve seen slow DNS lookups bring Linux systems to a crawl, and with our increasing reliance on online services, efficient DNS resolution is crucial. This article focuses on troubleshooting slow DNS lookups using systemd-resolved and resolvectl, which are integral to many modern Linux distributions.

Understanding systemd-resolved

systemd-resolved is a system service that provides DNS resolution, replacing traditional implementations like glibc’s resolver. It offers improved security, better DNSSEC handling, and efficient management of multiple DNS servers. To check if it’s running on your system, use:

Introduction to Dependency Troubleshooting

I’ve seen this go wrong when adding third-party repositories to a Linux system - it’s a great way to get the latest software, but it can also lead to broken dependencies and a whole lot of frustration. In this article, I’ll walk you through the practical steps to troubleshoot and resolve broken dependencies after adding a third-party repository.

Understanding Dependencies

Before we dive into troubleshooting, let’s take a step back and understand how dependencies work in Linux. Dependencies are packages that a particular package requires to function correctly. When you install a package, the package manager (such as apt or dnf) will automatically install any required dependencies. However, when adding third-party repositories, the package manager may not always be able to resolve dependencies correctly, leading to broken packages. Don’t bother with trying to manually resolve these dependencies - it’s a recipe for disaster.

Introduction to systemd Service Troubleshooting

I’ve seen this go wrong when services fail to start due to complex dependency ordering and logging issues. systemd, with its powerful tools for diagnosing problems, makes it easier to identify and fix these issues. In this article, we’ll focus on practical examples of using dependency ordering and journalctl to troubleshoot systemd service startup failures.

Understanding systemd Dependencies

systemd services are defined in unit files, typically located in /etc/systemd/system/ or /usr/lib/systemd/system/. These files specify the service’s dependencies, which are crucial for determining the order in which services start. Dependencies are defined using directives like Requires, Wants, Before, and After. For instance, a web server service might require the network service to be started before it can start itself.