When uploading files to HDFS using hdfs dfs -put, the replication factor defaults to the cluster-wide setting in hdfs-site.xml (typically 3). For temporary files, logs, or staging data, you often want a lower replication factor to reduce write latency and disk usage. Override Replication Factor at Upload Time Use the -D flag to pass HDFS…
When your Node.js application encounters a fatal error or needs to terminate, you need a reliable way to shut it down. Understanding how to exit gracefully—or forcefully when necessary—is essential for production applications. Using process.exit() The most direct method is process.exit(), which immediately terminates the Node.js process: process.exit(); This is a global method that doesn’t…
The URL hash — the fragment identifier after the # — serves several purposes: in-page navigation, client-side routing, and preserving application state. JavaScript provides straightforward APIs to read and monitor hash changes. Reading the Current Hash Access the hash using window.location.hash: const hash = window.location.hash; console.log(hash); // e.g., “#section-about” This returns the hash including the…
When handling POST requests in Node.js, you need to read the incoming data stream and parse it. The approach varies depending on whether you’re using raw Node.js http module, Express, or another framework. Using Express (Recommended) Express handles POST parsing automatically with built-in middleware. This is the standard approach for most modern Node.js applications: const…
While BIOS settings are the preferred way to disable USB 3.0, you can also force USB 2.0 mode on a running Linux system by manipulating the xHCI controller’s port routing register directly using setpci. How it works Intel xHCI controllers use the XUSB2PR (xHC USB 2.0 Port Routing Register) at offset 0xd0. Setting this register…
The simplest way to detect whether your Linux system booted in UEFI or BIOS (Legacy) mode is to check for the existence of the EFI firmware directory. Check for EFI Directory The /sys/firmware/efi/ directory only exists when the system has booted in UEFI mode. If it’s absent, the system is running in BIOS/Legacy mode. […
When you have SSH key-based authentication set up, the client will prefer it by default. This can make it difficult to test whether password authentication is working—especially after changing a password or troubleshooting login issues. Force password-only authentication Use the -o PreferredAuthentications=password flag: ssh -o PreferredAuthentications=password username@host This tells SSH to use password authentication exclusively,…
SSD performance varies significantly based on drive model, interface (NVMe vs SATA), and workload characteristics. Understanding how to benchmark your drives is more useful than memorizing typical specs—here’s how to measure actual throughput on your hardware. Basic Throughput Testing with dd The dd utility is the simplest way to measure sequential I/O performance. Here’s a…
When running tree across multiple servers or sharing output with teammates, you’ll notice the formatting can vary significantly. Some systems display box-drawing characters while others use ASCII pipes and dashes, making diff comparisons and documentation inconsistent. Understanding the Charset Differences The tree command respects the system’s locale and character encoding settings. By default, it will…
The git status command shows repository state visually, but when you need to detect it programmatically in bash — say, to fail a CI pipeline or prevent deployments — you need a different approach. Quick Method: Check Unstaged Changes The most reliable way to detect uncommitted changes is with git diff: if [[ -n $(git…
When you need the commit hash of the latest commit, there are several ways to get it. The most direct approach is using git log with format options rather than parsing output with grep. Using git log with –format The cleanest method is to use git log with the –format option: git log -1 –format=”%H”…
[md] gThumb’s preferences aren’t always obvious when you’re looking through the traditional menu bar. The location depends on your desktop environment and gThumb version. ## GNOME Desktop On GNOME 3 and later, preferences are accessed through the application menu rather than the window menu: 1. Open gThumb 2. Click the application name (“gThumb”) in the…
When working with file I/O in C on Linux, you’ll often need to convert between low-level file descriptors (returned by open(), socket(), etc.) and higher-level FILE pointers (returned by fopen()). This is common when integrating different libraries or mixing POSIX I/O with standard C I/O. Getting a FILE Pointer from a File Descriptor Use fdopen()…
Chrome stores passwords encrypted in the system keyring (GNOME Keyring, KWallet, or Pass depending on your desktop environment). To export them in plain text, you’ll need to create a temporary Chrome profile with basic (unencrypted) password storage, sync your passwords from Google Cloud, then extract them from the SQLite database. Prerequisites Chrome or Chromium installed…
When clients connect to your OpenWRT router via DHCP, they typically receive the router itself as the default gateway. Sometimes you need to advertise a different gateway — whether you’re running a proxy, load balancer, or multi-gateway setup on your network. This is done via DHCP option 3 (the router option in the DHCP specification)….
Once your HP printer is working on a Linux system, enabling the scanner requires installing SANE (Scanner Access Now Easy) and HP-specific backends. If wireless connectivity is already established for printing, the scanner should be discoverable on the same network. Install Required Packages On Fedora: sudo dnf install sane-backends sane-backends-devel hplip hplip-common On Ubuntu/Debian: sudo…
When troubleshooting email delivery or verifying mail server configuration, you need to look up the MX (Mail Exchange) records for a domain. On Linux, two tools handle this: host and dig. Both are reliable, though dig is generally preferred for its flexibility and cleaner output format. Using dig to query MX records The dig command…
Finding reliable, free image hosting is essential for developers, bloggers, and content creators. Your choice depends on your use case — whether you need temporary sharing, permanent hosting with transformations, or stock imagery. Imgur Imgur remains the straightforward choice for quick image sharing and temporary hosting. You can upload without an account, get an instant…
When an NFS server goes down or becomes unreachable, client mounts can end up in a “Stale NFS file handle” state. Standard umount and umount -f commands fail, leaving you stuck with an unusable mount point and no clean way to recover without rebooting. The solution is to use umount -l (lazy unmount), which immediately…
By default, Apache2 ignores .htaccess files. The AllowOverride directive controls which directives in .htaccess Apache will process. To enable .htaccess, you need to configure Apache to allow overrides. Enable AllowOverride Edit your Apache configuration file. On Ubuntu/Debian, this is typically: sudo nano /etc/apache2/apache2.conf Find the <Directory /var/www/> block and change AllowOverride None to AllowOverride All:…