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Modern Fedora systems keep multiple kernel versions available, but older kernels are tucked in a submenu rather than appearing as top-level GRUB2 entries. This requires a slightly different approach when setting them as your default boot option. Understanding the GRUB2 submenu structure When you run: grep menuentry /boot/grub2/grub.cfg | cut -d “‘” -f2 You’ll see…
If you use both the Chrome RSS Subscription Extension and Feedly, you can integrate them so that clicking the RSS icon in your browser automatically opens your feed in Feedly instead of the browser’s default handler. Understanding the Integration When you subscribe to an RSS feed through the Chrome extension, it needs a target URL…
Font sizes in Gnuplot plots often appear too small when scaling images down for papers or presentations. You can control font sizes at multiple levels: globally for the terminal, for axis labels and tick marks, for legends, and for individual text elements. Global Terminal Font Size Set a default font and size for your entire…
The common claim that cin is significantly slower than scanf in C++ is partially true, but only when comparing default configurations. The reality is more nuanced. Why cin Can Be Slower by Default By default, C++ streams maintain synchronization with C stdio streams (stdin, stdout, stderr). This synchronization requires additional overhead because the library must…
To load and execute code from a source file in the OCaml interactive toplevel, use the #use directive: #use “file-name”;; This reads, compiles, and executes OCaml phrases from the specified file as if you’d typed them directly into the toplevel. Execution stops at the first error encountered. Common use cases Loading utility functions If you…
Chrome supports proxy configuration via command-line flags, which is useful for scripting, automation, or testing without touching the GUI settings. This works across all major Linux distributions. Basic proxy configuration Use the –proxy-server flag when launching Chrome: google-chrome –proxy-server=”socks://localhost:8080″ Proxy scheme formats The proxy specification follows this format: [<proxy-scheme>://]<proxy-host>[:<proxy-port>] Supported schemes: http — HTTP proxy…
Controlling a GNOME desktop remotely—locking the display, activating the screensaver, or blanking the screen—requires you to interact with the running GNOME session. The approach depends on your GNOME version and what you’re trying to accomplish. Using systemd User Sessions and D-Bus Modern GNOME (3.30+) uses systemd user sessions and D-Bus for session management. The older…
When a disk fails on a server with multiple drives, you need to identify which physical SATA port it’s connected to. Linux device names (sda, sdb, etc.) don’t necessarily map to SATA port order, especially after disk failures or in systems with mixed storage. Using lsblk with Device Paths The lsblk command provides a quick…
Swap space is essential for system stability, allowing the kernel to move less-frequently-used memory pages to disk when physical RAM is exhausted. Here’s how to set up a dedicated swap partition. Step 1: Create the Partition Use fdisk, gdisk (for GPT disks), or parted to create a new partition. For modern systems with GPT partition…
Linux can manage multiple swap partitions or files simultaneously, each with an assigned priority. The kernel allocates swap pages from highest to lowest priority, with round-robin allocation among equally-prioritized areas. Setting Swap Priority with swapon Use the swapon command to activate a swap partition and set its priority: swapon -p 10 /dev/sdc1 The -p flag…
To disable all active swap spaces on Linux, run: swapoff -a The -a flag targets all currently enabled swap devices and files. This forces the kernel and applications to rely entirely on physical RAM. When You’d Do This Disabling swap is useful for: Performance testing: Eliminating swap I/O variance to get consistent benchmarks Latency-sensitive workloads:…
LaTeX is a document preparation system widely used for scientific and technical documents. Most modern workflows use pdflatex or xelatex to compile directly to PDF, avoiding the outdated DVI → PostScript → PDF pipeline. Debian/Ubuntu sudo apt-get update sudo apt-get install texlive-latex-base texlive-latex-extra texlive-fonts-recommended For a complete installation with all packages: sudo apt-get install texlive-full…
Shortcut Action Ctrl+T Open new tab Ctrl+N Open new window Ctrl+Shift+N Open new Incognito window Ctrl+Shift+T Reopen last closed tab (Chrome remembers up to 10 closed tabs) Ctrl+1 through Ctrl+8 Jump to tab at specified position Ctrl+9 Jump to last tab Ctrl+Tab or Ctrl+PgDn Switch to next tab Ctrl+Shift+Tab or Ctrl+PgUp Switch to previous tab…
No-IP provides dynamic DNS service for systems that don’t have static IP addresses. The noip2 client daemon monitors your system’s IP and automatically updates your No-IP domain when changes occur. Here’s how to set it up properly. Prerequisites You’ll need: A No-IP account with at least one hostname configured Root or sudo access A Linux…
Kernel parameters often need to be passed to Xen DomUs during boot or for troubleshooting. Common scenarios include booting into single-user mode for recovery, enabling kernel debugging, or adjusting memory/CPU settings at runtime. Using the extra parameter The simplest method is passing kernel parameters via the extra= option when creating or starting a DomU. For…
When working with relative paths in Linux, you often need the absolute path for scripting, logging, or passing to other programs. Several tools can resolve this, each with different strengths. Using readlink The readlink command is the traditional tool for this job. The -f flag follows symlinks and resolves the path to its absolute form:…
Dropbox on Linux has two main approaches: the official daemon (headless) or the sync client with GUI. Which you choose depends on your use case. Official Dropbox Daemon (Recommended for Servers) The daemon is lightweight and works well on headless systems. Download and extract it: cd ~ && wget -O – “https://www.dropbox.com/download?plat=lnx.x86_64” | tar xzf…
A hard link is an additional directory entry pointing to the same inode as the original file. Unlike symbolic links, hard links share the same inode number and have identical permissions, ownership, and content. To find all hard links to a file, you need to locate every directory entry with the same inode. Using find…
LVM (Logical Volume Management) abstracts physical storage into logical volumes, giving you flexibility to resize filesystems, snapshot data, and manage disk space without downtime. It sits between your physical disks and the filesystems you mount. The three core LVM concepts are: Physical Volumes (PVs): Physical disks or disk partitions Volume Groups (VGs): Collections of PVs…
When you need to verify that two Linux systems can communicate over a specific protocol and port, you have several solid options. Let’s cover the most practical approaches. Using nc (netcat) The nc command remains a reliable choice for quick connectivity tests. It’s widely available and requires no special setup. TCP connection test To listen…