When a hard drive fails physically, data recovery becomes challenging but sometimes possible. If the drive isn’t recognized by the system or showing signs of mechanical failure, professional recovery services may be necessary—but they’re expensive. Before going that route, you can attempt recovery yourself using open-source tools. When to attempt DIY recovery You can safely…
When you’re managing a Linux server remotely over SSH, determining whether a USB drive has been connected requires checking kernel messages and device listings since you can’t visually inspect the hardware. Check dmesg for USB Detection Events The most reliable method is examining kernel logs with dmesg. When a USB device is detected, the kernel…
Connecting your application to a MySQL database is fundamental to most backend systems. Rather than shelling out to the mysql command-line client, you’ll use language-specific connectors that provide proper connection pooling, error handling, and prepared statements. Language-Specific MySQL Drivers The best approach depends on your tech stack: Python Use mysql-connector-python for straightforward connections or PyMySQL…
GNU Screen is a terminal multiplexer that lets you manage multiple shell sessions within a single window. If you’re new to it, here are the best resources to get up to speed, plus practical tips for getting started. Getting Started with Screen For an introduction to the basics, start with A quick tutorial on screen….
Converting text to lowercase is a common task in shell scripts and command-line workflows. Linux offers multiple approaches, each with different trade-offs in performance, portability, and Unicode handling. Using tr for simple conversions The tr command translates characters and is widely portable across Unix-like systems: echo “HELLO WORLD” | tr ‘[:upper:]’ ‘[:lower:]’ Output: hello world…
When a filesystem listed in /etc/fstab fails to mount during boot, the system can hang or drop to an emergency shell, preventing normal startup. This happens because the kernel treats all mount entries equally by default. Non-critical filesystems—network shares, external drives, or optional data partitions—shouldn’t block your entire system from booting. Understanding fstab mount options…
Merging PDFs on Linux is straightforward with several tools available, each suited to different needs. Whether you need a quick command-line merge or want to reorder pages visually, here’s what works best. pdfunite: The Simplest Approach The fastest way to merge PDFs is with pdfunite from poppler-utils: pdfunite file1.pdf file2.pdf file3.pdf output.pdf Install it if…
Managing a cluster of servers, you’ll want to be notified when they come back online after restarts or unexpected reboots. Email notifications on boot let you track infrastructure changes and catch potential issues early. Using crontab @reboot The simplest approach is a crontab @reboot entry that runs once at startup. This executes before most services…
The standard crontab -e command opens an interactive editor, which doesn’t work in automated scripts. To add crontab entries non-interactively, you need to pipe a list of cron jobs directly to crontab -. Basic approach The simplest method reads the existing crontab, appends your new entry, and writes it back: (crontab -l 2>/dev/null; echo “@reboot…
When a kernel panic occurs on a remote Linux server, manual intervention via SSH becomes impossible. The kernel can be configured to automatically reboot after a panic, allowing the system to recover without human intervention. Enable Kernel Panic Auto-Reboot The kernel.panic parameter controls this behavior. A value of 0 disables auto-reboot; any positive integer specifies…
The core problem here is legitimate: if you’re running multiple jobs on the same dataset where the mapper phase produces identical intermediate results, recomputing those results is wasteful. However, skipping the mapper phase entirely breaks MapReduce’s processing model. There are better approaches. Why You Can’t Just Skip the Mapper MapReduce assumes data flows through map…
Finding files that match a pattern is straightforward with ls *string* or find . -name ‘*string*’. But excluding files with a certain string in their filename requires a different approach. Using find with negation The most reliable method is find with the ! (or -not) operator: find . -type f ! -name ‘*string*’ This finds…
HDFS doesn’t natively support directory-level replication factor inheritance. Even if you set a specific replication factor on a directory and its files, new files created in that directory will default to the cluster’s global dfs.replication setting (typically 3). This limitation can complicate multi-tier storage strategies where you want temporary or low-priority data on fewer replicas…
Rocky Linux 9 can blank the console screen after a period of inactivity, but by default it may not actually power off the display. This is often caused by kernel mode settings or DPMS (Display Power Management Signaling) configuration. Check Current DPMS Status First, verify whether DPMS is enabled on your console: cat /sys/module/kernel/parameters/consoleblank If…
[md] vbetool is a utility for executing real-mode x86 BIOS calls, commonly used for power management and display mode switching on legacy systems. Rocky Linux 9 doesn’t include it in standard repositories, so you’ll need to build it from source. ## What vbetool Does vbetool communicates with the video BIOS through the Video BIOS Extensions…
RPM Fusion provides packages that Fedora and RHEL can’t ship by default due to patent, licensing, or trademark restrictions. This includes multimedia codecs, proprietary drivers, and other software. Here’s how to enable it on RHEL 9 and Rocky Linux. Enable RPM Fusion Free and Non-Free # Enable EPEL first (required dependency) sudo dnf install epel-release…
The sed stream editor is the go-to tool for deleting lines from files in Linux. It’s fast, works on large files without loading everything into memory, and handles complex patterns easily. Delete a Single Line by Line Number To delete the 4th line from a file: sed -i ‘4d’ ./file The -i flag edits the…
Converting between Simplified Chinese (SC) and Traditional Chinese (TC) characters on Linux is straightforward with OpenCC, a mature open-source tool designed specifically for this task. Installing OpenCC Most distributions include OpenCC in their standard repositories: # Debian/Ubuntu sudo apt install opencc # RHEL/CentOS/Fedora sudo dnf install opencc # Arch sudo pacman -S opencc Alternatively, build…
Converting PPTX presentations to image files on Linux requires a two-step process: first convert to PDF, then rasterize to your target image format. This approach preserves slide layout and fonts better than direct conversion tools. Convert PPTX to PDF Start by converting your PowerPoint file to PDF using LibreOffice: libreoffice –headless –convert-to pdf presentation.pptx The…
Fedora’s default repositories don’t include musl libc, but you have two practical options: install it from a community repository if available, or build from source. Building from source gives you full control and is the most reliable approach across Fedora versions. Option 1: Build from Source (Recommended) Start by installing the build dependencies: sudo dnf…