Virtual hosts allow you to serve multiple websites from a single Apache server and IP address. This is the standard approach for shared hosting and cost-effective server deployments. Basic Virtual Host Setup The foundation of multi-site hosting on Apache is the VirtualHost directive. Each domain needs its own block that specifies where its files live…
Firefox uses a profile system to isolate settings, extensions, bookmarks, and browsing data. By default, Firefox only allows one instance per profile to run at a time—new instances redirect to the existing process. If you need multiple Firefox windows with different profiles open at once, you need to disable this behavior. The -no-remote Flag The…
The nomodeset kernel parameter tells Linux to disable kernel mode setting (KMS), forcing the graphics driver to use basic VESA modes instead of native driver features. This is useful for troubleshooting display issues during boot or installation. When You Need nomodeset Common scenarios that require nomodeset: Black screen during boot with certain GPUs (especially Nvidia…
When you need writes to one or more files to automatically go to another file, you have several options depending on your exact use case. The most common scenario is capturing output from commands, monitoring file changes, or duplicating writes across multiple destinations. Using tee for Command Output Duplication The tee command duplicates standard input…
A 403 Forbidden error when running git push means your credentials aren’t valid or you lack permission to access the repository. This is one of the most common Git frustrations, but it’s usually fixable once you understand what’s actually happening. Why 403 Errors Happen Your authentication method has expired or been revoked Your GitHub Personal…
Skype periodically fails to start with a “system is unavailable” error when it can’t read or write to the user’s temporary directory. This typically happens when the temp folder becomes corrupted, has permission issues, or contains orphaned Skype cache files that prevent proper initialization. Understand the Problem On Windows, each user account has a temporary…
Long lines in text files can be difficult to read in a terminal. Linux provides several built-in tools to wrap or fold long lines to fit your screen width, each with different strengths. Using fold — Simple Line Wrapping fold wraps lines at a specified character width: # Wrap at 80 characters fold -w 80…
When you wrap your WordPress site in a native Android app using WebView, Google’s AdSense policy prohibits serving those ads through the app wrapper. You need to hide AdSense on mobile views while keeping them on desktop, and ideally detect when your site is loaded inside a WebView to block ads there too. Detecting Mobile…
When you fork a repository on GitHub or GitLab, your copy diverges from the original as upstream maintainers merge new changes. To keep your fork current, you need to regularly sync it with the upstream repository. Setting up the upstream remote First, check your current remotes: git remote -v You’ll see origin (your fork). Add…
[md] By default, Fedora doesn’t enable SSH access. You’ll need to install OpenSSH server, start the service, and configure your firewall to allow connections. ## Install OpenSSH Server sudo dnf install openssh-server openssh-clients The openssh-clients package provides the ssh command for connecting to other machines, while openssh-server allows incoming connections. ## Start and Enable the…
The default display manager on Fedora is GNOME Display Manager (GDM). If you want to switch to another display manager like KDE Plasma (SDDM), LightDM, or another option, you need a reliable method that won’t break your system. Using system-switch-displaymanager The most straightforward approach is the system-switch-displaymanager utility, which handles the systemd configuration for you….
OpenWrt runs Dropbear as its SSH server instead of OpenSSH. While Dropbear supports RSA and modern key types, the authorized_keys file lives in a different location, which causes ssh-copy-id to fail silently. Here’s how to set up key-based authentication properly. Why ssh-copy-id doesn’t work ssh-copy-id looks for ~/.ssh/authorized_keys on the remote system, which is OpenSSH’s…
When you have multiple static libraries (.a files) and need to combine them into a single archive, GNU ar provides several approaches. The most straightforward method uses ar‘s MRI mode for clarity and maintainability. Using ar MRI Mode The cleanest approach is to use ar -M with an MRI script. This method is explicit and…
Windows 7 stuck in an update loop—where Windows Update fails repeatedly and triggers automatic reboots—is a frustrating problem that stems from a corrupted or problematic update package. The system keeps attempting to install the same failed update on each boot, creating a cycle you can’t escape without intervention. Identify the Problematic Update The first step…
systemd uses targets instead of the old sysvinit runlevels. Runlevel 3 (console mode) maps to multi-user.target. Here’s how to boot directly to console on Fedora, RHEL, Debian, Ubuntu, and other systemd-based distributions. Switch to Console Mode Immediately To switch from graphical mode to console without rebooting: sudo systemctl isolate multi-user.target This immediately stops the display…
Fedora uses systemd-tmpfiles to automatically clean up temporary files and directories. By default, this includes volatile files in /tmp/, which can cause problems for applications that rely on files persisting there — like HDFS DataNodes that store their PID files as hadoop-hadoop-datanode.pid. How systemd-tmpfiles Works The systemd-tmpfiles service runs periodically (typically daily and at boot)…
You may need to deactivate a LVM volume group to make it unknown to the kernel — typically before removing disks, migrating storage, or performing maintenance. The vgchange command handles this with the -a (or –activate) flag. Basic deactivation To deactivate a volume group named vg, use: vgchange -a n vg The -a n flag…
BuySellAds wraps backfill ads in iframes by default, which violates Google AdSense’s terms of service. If you’re using AdSense as your backfill network, you need to inline the ad code directly on the page instead. The Problem Google AdSense explicitly prohibits serving ads within iframes on most placements. BuySellAds’ default behavior of wrapping backfill ads…
Vim supports Xterm 256-color codes on Linux and modern terminals. Understanding the color palette and how to use it in your configuration is essential for building readable syntax highlighting schemes and custom colorschemes. The 256-Color Palette Xterm’s 256-color mode consists of: Colors 0-15: Standard ANSI colors (black, red, green, yellow, blue, magenta, cyan, white, and…
When you connect an external hard drive with LVM volumes to a RHEL, CentOS, or Rocky Linux system, the logical volumes don’t automatically appear in /dev. Unlike some distributions that handle this automatically, you need to manually activate them using vgchange. Activating LVM Volumes First, plug in your external drive. Then activate all logical volumes…