When a new kernel lands, the kernel‑specific modules and initramfs changes can
break the ExecStartPre or ExecStart scripts that a timer relies on.
The result? A timer that never fires, or that fires with the wrong environment.
Below is a step‑by‑step guide to diagnose and restore a broken timer, with security‑aware notes and trade‑offs you’ll run into in a production or homelab setup.
[Read More]Kernel upgrades are usually painless, but on a few systems they can trigger a cascade of “carrier lost” messages that make the interface drop and come back up repeatedly. The messages are buried deep in the system journal, so you may not notice them until the network flaps start causing outages. This post shows how to locate those hidden messages with journalctl, correlate them with real‑world symptoms, and apply a fix that keeps the interface stable.
/etc/hosts, the file often ends up with Windows‑style CRLF line endings.If you’ve ever pulled a hosts file from a Windows share, you’ve probably noticed that the resolver starts acting weird. The glibc resolver stops at the carriage return (\r) and treats the rest of the line as part of the hostname. That means lookups for localhost, myserver, or any entry that follows a stray CR fail, and some services silently fall back to DNS—exposing the system to name‑resolution attacks.
I’ve seen this go wrong when a service is misconfigured and ends up consuming all your system resources. Systemd is a core component of most modern Linux distributions, responsible for managing system services. One of its key features is the ability to automatically restart services that fail or exit unexpectedly. However, if not properly configured, this can lead to a “service deluge” where a failing service is repeatedly restarted.
[Read More]When your Linux system fails to boot, it can be frustrating - especially if you’re not familiar with the troubleshooting process. I’ve seen this go wrong when people don’t know where to start. Luckily, systemd’s Emergency Mode and Rescue Shell are here to help. In this article, we’ll dive into how to use these tools to troubleshoot initramfs issues and get your system up and running again.
[Read More]When working with Linux systems, logs are an essential part of troubleshooting, monitoring, and maintaining the health of your system. However, with the vast amount of data being logged, it can become overwhelming to sift through the noise to find the important information. I’ve seen this go wrong when trying to debug a complex issue, only to get lost in a sea of irrelevant log messages. This is where journalctl comes in, a powerful tool for managing and filtering system logs.
When working with Linux systems, especially those using systemd as the init system, service management is crucial for maintaining system stability and functionality. I’ve seen this go wrong when a service fails to restart properly, often due to dependency ordering issues or retry policy misconfigurations. Understanding how to troubleshoot and resolve these issues is essential for ensuring system reliability and uptime.
Systemd services can have complex dependencies, defined in their service files (typically located in /etc/systemd/system/ or /usr/lib/systemd/system/). These dependencies are crucial for ensuring that services start in the correct order. For example, a web server might depend on the network service to be started before it can operate. Misconfigured dependencies can lead to services failing to start or restart. The real trick is to understand the startup sequence and identify potential bottlenecks.
I’ve seen this go wrong when working with Linux systems: a service enters a restart loop, and it’s not immediately clear why. These loops occur when a service fails to start or restarts repeatedly, often due to dependency issues or configuration problems. In practice, identifying the root cause can be tricky, but there are some practical steps you can take to troubleshoot systemd service restart loops.
[Read More]I’ve seen my fair share of DNS issues on Linux, and one tool that’s always helped me resolve them is resolvectl. This command-line utility, part of the systemd suite, provides a comprehensive way to query and configure DNS settings on your system. In this article, I’ll share some practical examples of how to use resolvectl to diagnose and fix stubborn DNS issues.
Before diving into resolvectl, it’s essential to understand how DNS resolution works on Linux. The DNS (Domain Name System) is responsible for translating human-readable domain names into IP addresses that computers can understand. On Linux systems, DNS resolution is typically handled by a resolver, which queries DNS servers to resolve domain names. The resolver configuration is usually defined in /etc/resolv.conf, but with systemd, resolvectl offers a more integrated and dynamic way to manage DNS settings.
I’ve seen many Linux systems become cluttered over time, making it harder to manage packages and maintain security. That’s where find and xargs come in - two powerful command-line tools that can help you clean up your system. In this article, I’ll show you how to use these tools to safely remove unused packages on your Linux system.
The find command is incredibly versatile, allowing you to search for files based on various conditions like file name, size, modification time, and more. xargs, on the other hand, builds and executes command lines from standard input. By combining these two tools, you can automate the process of finding and removing unused packages. Don’t bother with manual searches - find and xargs can save you a lot of time and effort.