When you need to verify the current link speed of a network interface — whether it’s running at 10Mbps, 100Mbps, 1Gbps, or higher — ethtool is the standard tool for the job. Using ethtool to check interface speed The basic command is straightforward: ethtool eth0 Replace eth0 with your actual interface name. Here’s sample output:…
When troubleshooting wireless performance, you need to know both the negotiated link speed and actual throughput. ethtool won’t help here — it’s for wired interfaces. For wireless adapters, you’ll need different tools depending on what information you’re after. Using iwconfig for link speed The iwconfig command shows the currently negotiated link rate between your adapter…
SSH performs reverse DNS lookups on connecting clients by default. If your DNS infrastructure is slow or misconfigured, this can add several seconds to every login attempt. Disabling this lookup is a straightforward performance optimization, especially in cloud environments where internal IPs often lack valid PTR records. Disable the UseDNS Setting Edit /etc/ssh/sshd_config: sudo nano…
The scp command supports bandwidth limiting through the -l flag, which caps the transfer rate in Kbit/s. This prevents large file transfers from saturating your network connection. Basic Usage The -l flag specifies the maximum bandwidth in kilobits per second (Kbit/s): # Limit to 1000 Kbit/s (approximately 125 KB/s) scp -l 1000 largefile.tar.gz user@remote:/path/to/destination/ #…
Setting up OpenVPN on an iPhone with Ovpn Spider requires a few specific steps since iOS has limitations compared to desktop environments. This guide walks you through the process. Prerequisites You’ll need: An iPhone running iOS 12 or later The OpenVPN Connect app installed from the App Store A valid .ovpn configuration file from Ovpn…
When you need to browse the web over SSH or in a headless environment, graphical browsers aren’t an option. Several terminal-based browsers exist that actually handle modern websites reasonably well, though with limitations around JavaScript and CSS. Lynx Lynx is the oldest and most established terminal browser, first released in 1992. It’s still actively maintained…
Accessing blocked websites from mainland China on an iPhone requires a VPN or proxy solution that can bypass the Great Firewall. This guide covers practical approaches and tools that work as of 2026. VPN Solutions for iOS The most reliable method is using a VPN app. Several options are available: Commercial VPN Services Paid VPN…
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…
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….
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…
The default dd command can feel sluggish because it uses a small block size (512 bytes) by default. You can dramatically improve throughput by increasing the bs (block size) parameter. Basic optimization Instead of: dd if=/dev/sda2 of=./sda2.bak Use: dd if=/dev/sda2 of=./sda2.bak bs=1M The bs parameter controls how much data dd reads and writes in each…
Resizing a single image is straightforward, but processing dozens or hundreds requires automation. ImageMagick’s convert command (or the modern magick command) paired with a bash loop is the standard approach for batch image resizing on Linux. Using ImageMagick ImageMagick remains the most reliable tool for this task. Here’s a practical script to resize all images…
Removing version control or build artifact directories across a large directory tree is a common sysadmin task. SVN directories (.svn), Git metadata (.git), or node modules (node_modules) often need to be purged before deployment or archiving. Using find with xargs The most efficient approach combines find with xargs: find ./ -name “.svn” -type d |…
In HDFS, files are split into blocks and replicated across multiple DataNodes for fault tolerance and parallelism. When you need to know exactly which DataNodes hold a specific file’s blocks, use hdfs fsck with the -locations and -blocks flags. Basic command hdfs fsck /path/to/file -files -locations -blocks This queries the NameNode and returns the block…
Converting FLV files to MP4 is straightforward with FFmpeg. The basic command takes just seconds: ffmpeg -i input.flv output.mp4 FFmpeg will automatically select suitable video and audio codecs for MP4 format. This works for most FLV files without additional configuration. Preserving original quality If you want to skip re-encoding and copy the streams as-is, use…
When you need just the files from a specific branch without downloading the entire repository history, use shallow cloning. This is useful for large repositories where full history takes time to transfer, or when you only care about the current state of a particular branch. The core command is: git clone -b branch-name <repository-url> –depth…
When you need to completely wipe a USB drive on Windows, you have several reliable options. Choose based on your security requirements: Disk Management for quick reformatting, DiskPart for automation, or secure erasure tools if the drive contained sensitive data. Using Windows Disk Management The simplest built-in approach: Connect the USB drive Open Disk Management…
The most reliable way to download YouTube videos is yt-dlp, a maintained fork of youtube-dl that handles modern YouTube changes and DRM protections. It works on Linux, macOS, and Windows. Installation Linux (Debian/Ubuntu): sudo apt install yt-dlp Linux (Fedora/RHEL): sudo dnf install yt-dlp macOS: brew install yt-dlp Windows or any system with Python 3.8+: pip…
When processing text files or command output, non-printable ASCII characters corrupt formatting, break parsing, or create unexpected behavior. You need the right tool for your specific case — whether you’re stripping control characters, handling UTF-8, or cleaning up embedded escape sequences. Understanding Printable ASCII The standard printable ASCII range includes: Tab (hex 09) Line Feed…
The simplest approach creates a JAR with just your project’s compiled classes: sbt package This outputs to target/scala-2.x.y/projectname_2.x.y-zz.jar. The naming convention includes the Scala version to prevent classpath conflicts when multiple Scala versions coexist. For iterative development, use watch mode: sbt ~package This rebuilds the JAR after every source change. However, this JAR only contains…