Getting the directory path of a running script is a common requirement in bash, whether you’re sourcing files, building paths to config directories, or navigating relative to the script itself. The naive approach often fails with symbolic links or when the script is sourced rather than executed directly. The Problem Using $0 alone is unreliable….
By default, xargs appends its input as arguments at the end of the command. This works fine when you need a utility once per item, but becomes problematic when you need to reference the same input multiple times in different positions. The Problem Consider renaming files by appending .bak to each filename. You might try:…
When you run a command like this in Bash: ssh host1 hostname &; ssh host2 hostname & You get an error: bash: syntax error near unexpected token `;’ The issue stems from how Bash interprets command separators. The & and ; characters are both command terminators, but they serve different purposes, and Bash has strict…
Extracting images embedded in PDF files is straightforward on Linux with several reliable tools. Here are the most practical approaches, from GUI tools to command-line solutions. GUI Tools LibreOffice Draw remains the simplest option if you prefer a graphical interface. Open the PDF file in LibreOffice Draw, right-click on any image, and select “Save Image…
If you’ve downloaded a Windows ISO file but lack a DVD drive, creating a bootable USB installation drive is straightforward. This works for Windows 10, 11, and later versions. Using the Windows Media Creation Tool Microsoft’s official approach is the Windows Media Creation Tool, which is more current and reliable than older third-party utilities. Download…
When stop-dfs.sh fails to cleanly terminate DataNode processes, you’re left with orphaned Java processes consuming resources and potentially causing cluster issues. This happens most often after ungraceful cluster shutdowns or when the standard stop script encounters communication problems with specific nodes. Understanding the Problem The typical symptom is stop-dfs.sh reporting that certain nodes have no…
When a process mmaps and mprotects many memory ranges, you’ll eventually hit the kernel limit and start seeing ENOMEM errors from mprotect() calls. This happens because Linux maintains internal kernel structures for each mapped range, and there’s a hard ceiling on how many the kernel will track per process. The culprit is the vm.max_map_count sysctl…
When you connect an external keyboard to your laptop, accidental key presses from the built-in keyboard can be annoying. Disabling it entirely is straightforward on Linux and can save you from errant inputs while keeping the option to re-enable it when needed. Find Your Keyboard Device Start by listing all input devices to identify your…
Monitoring directory growth is essential for tracking logs, temporary files, and catching runaway disk usage before it becomes a problem. Linux offers several approaches depending on whether you need simple periodic checks, interactive exploration, or event-driven monitoring. Simple periodic monitoring The watch command repeatedly runs a command at set intervals: watch -n 1 du -sh…
Writing a master thesis means protecting years of work. You need to handle three core concerns: preventing data loss from hardware failure or malware, ensuring 24/7 access to your work, and keeping it private until publication. The solution is version control with remote backup. Git provides local history and recovery, while a private remote repository…
Merging SAM files is a common task in bioinformatics workflows, and while samtools merge works directly with BAM files, you need a different approach for SAM files. The most efficient method leverages the SAM format structure: headers start with @, and alignment records don’t. Why not convert to BAM first? Converting SAM to BAM, merging…
The /etc/sysconfig/network-scripts/ directory contains network configuration files on RHEL and Fedora systems. While newer systems increasingly use NetworkManager and systemd-networkd, understanding ifcfg files remains essential for legacy systems and certain enterprise environments. Basic Static IP Configuration Here’s a typical ifcfg-eth0 file for a static IP setup: DEVICE=eth0 TYPE=Ethernet BOOTPROTO=none ONBOOT=yes IPADDR=192.168.1.151 NETMASK=255.255.0.0 GATEWAY=192.168.1.10 USERCTL=no The…
When submitting images to publishers or print shops, you’ll often need CMYK color space instead of RGB. The conversion is straightforward on Linux using ImageMagick’s convert command. Basic conversion The simplest approach uses the -colorspace option: convert from.tif -colorspace CMYK to.tif This works, but CMYK TIFF files can be quite large. Add compression to keep…
PowerPoint’s export function defaults to 96 DPI, which is suitable for screen display but inadequate for printing posters, documents, or any material requiring high resolution. While PowerPoint includes DPI settings, they’re often unreliable or have limited effect on TIFF output. Here are the practical methods to generate proper high-DPI TIFF files from PowerPoint slides. PowerPoint’s…
The git diff –word-diff output is clean and readable for tracking changes at the word level instead of line-by-line. If you need that functionality outside a git repository—or just want a standalone tool—wdiff is purpose-built for exactly this. Using wdiff for word-level diffs wdiff compares two files word by word, where a word is defined…
Many PDF-to-text conversions strip away formatting and spatial relationships, making tables unreadable and multi-column layouts collapse into linear text. If you need to preserve the relative positions of text elements—especially tables, columns, and indentation—you have several solid options. pdftotext with layout preservation The simplest approach is pdftotext, which comes with most distributions as part of…
When pushing to GitHub over HTTPS, you’ll see: error: The requested URL returned error: 403 Forbidden while accessing https://github.com/username/repo.git fatal: HTTP request failed This means Git connected to GitHub successfully, but your credentials were rejected. Common causes: Expired or revoked Personal Access Token (PAT) Using a password instead of a PAT (GitHub disabled password auth…
The TP-LINK T2U is a USB WiFi adapter based on the MediaTek MT7650U chipset. While Linux kernel support has improved significantly, you may still need to manually compile drivers on some distributions. This guide covers installation on modern Fedora and RHEL-based systems. Check if your adapter is already supported First, plug in the adapter and…
The free command—along with ps, top, kill, pgrep, and dozens of other system utilities—is maintained as part of the procps-ng project. Source repository The source code is hosted at: https://gitlab.com/procps-ng/procps You can clone it with: git clone https://gitlab.com/procps-ng/procps.git cd procps Most distributions package procps-ng, so you likely already have it installed. You can verify the…
Serializing objects to JSON is a fundamental task in Node.js for APIs, databases, and file storage. The approach depends on your object complexity and performance requirements. Basic Conversion with JSON.stringify The standard approach uses the built-in JSON.stringify() method: const myObject = { name: ‘John’, age: 30, email: ‘john@example.com’ }; const jsonString = JSON.stringify(myObject, null, 2);…