Docker containers persist on disk even after they exit. For quick testing and one-off tasks, you don’t need that leftover cruft. Use the –rm flag to automatically delete containers when they stop. The –rm Flag The –rm option tells Docker to remove the container as soon as it exits. This is useful for: Quick tests…
Hex-encoded strings are common in system administration, debugging, and network packet analysis. Whether you’re examining binary data, decoding network protocols, or troubleshooting data encoding issues, you’ll often need to convert between hex and ASCII representations. xxd is the standard tool for this task on Unix-like systems. It creates hexdumps and reverses them back to binary…
This document provides the essential software versions and upgrade instructions for running Linux 2.0.x kernels successfully. It covers package compatibility, known issues, and practical solutions for system administrators upgrading from earlier kernel releases. Networking Configuration The loopback route configuration in many older network scripts is incorrect and will cause kernel errors in 2.0.x. Look for…
This document preserves the original Linux 1.0 release notes (source: linux-1.0.tar.gz), released in March 1994. It’s a snapshot of early Linux kernel development and shows the rapid pace of improvement during the pre-1.0 era. The original ASCII formatted version appears at the end of this post. Changes since 0.99 patchlevel 15 Removed all the bugs,…
This document preserves the original release notes for Linux kernel v0.97, an early milestone in kernel development that demonstrates the rapid evolution of core subsystems in the 1990s. The content below has been reformatted from the original ASCII release notes for readability while maintaining historical accuracy. Changes in 0.97 Display and graphics support VESA support…
CPU affinity pins a process to specific CPU cores, reducing context switches and improving cache locality. This matters when you need consistent latency or want to isolate workloads on multi-core systems. Using taskset taskset is the standard tool for setting CPU affinity on running processes. The basic syntax: taskset -p -c 0,1,2 <pid> This binds…
The default data directory for MySQL and MariaDB installed from official repositories on modern distributions is: /var/lib/mysql This applies to CentOS 7, Rocky Linux 9, Fedora, and most RHEL-based systems. Finding the Data Directory Programmatically If you’ve customized your installation or need to verify the exact location, there are several reliable methods. Query MariaDB/MySQL Configuration…
When a Bash script spawns child processes—say script A starts B, which starts C, which runs rsync—you need a way to terminate the entire process tree cleanly. Simply killing the parent leaves orphaned children running in the background. The most reliable approach uses session IDs (SID). By default, child processes inherit the same session ID…
The standard way to get your running process’s PID in Go is through the os package: package main import ( “fmt” “os” ) func main() { pid := os.Getpid() fmt.Println(“Current PID:”, pid) } os.Getpid() returns an int representing the current process’s ID. This works across all platforms—Linux, macOS, Windows, and others. Getting the Parent Process…
When upgrading libvirt from an older version (like 1.2.2) to 2.5.0 or later, you may encounter a socket connection error when trying to create VMs: ERROR Failed to connect socket to ‘/var/run/libvirt/virtlogd-sock’: No such file or directory Domain installation does not appear to have been successful. This happens because libvirt 2.5.0 introduced the virtlogd daemon…
The usermod command is the standard tool for modifying user accounts. To change a username, use the -l (or –login) option: sudo usermod -l user1 u1 This changes the login name from u1 to user1. However, there’s an important caveat: usermod only updates the /etc/passwd file. The user’s home directory, mail spool, and other resources…
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…
Securing your website with HTTPS is no longer optional—it’s essential for SEO, user trust, and browser compatibility. The good news: Let’s Encrypt provides free certificates, and the tooling has matured significantly. Using Certbot with Nginx or Apache The standard approach is Certbot, which automates certificate issuance and renewal: sudo certbot –nginx This automatically configures HTTPS…
When running Hadoop on systems with substantial memory, the default 1GB heap size is often inadequate. If you check running processes with ps aux and see -Xmx1000m, you’re working with the default configuration that doesn’t scale to modern hardware. Understanding Hadoop Heap Configuration Hadoop’s Java process memory is controlled by environment variables set in configuration…
To toggle between Simplified Chinese and Traditional Chinese input modes in ibus-libpinyin, press Ctrl+Shift+F. This shortcut has been the standard method since ibus-pinyin 1.3.7 and works across modern versions. Common ibus-libpinyin Shortcuts Beyond script conversion, these shortcuts handle daily input tasks: Shortcut Function Ctrl+Shift+F Toggle Simplified/Traditional Chinese Ctrl+. Toggle full-width/half-width punctuation Ctrl+, Toggle English/Chinese punctuation…
When converting PostScript to PDF using ps2pdf with certain PDFSETTINGS options, you may hit this error: GPL Ghostscript 9.10: Set UseCIEColor for UseDeviceIndependentColor to work properly. Unrecoverable error: stackunderflow in .setdistillerparams This occurs when Ghostscript’s internal stack runs out of expected values during PDF distiller parameter processing. The root cause is usually conflicting color space…
Gnuplot can output directly to EPS (Encapsulated PostScript) format, which is useful for including plots in LaTeX documents and other publishing workflows. Direct EPS Output The simplest approach is to set the terminal to postscript with the eps option before plotting: set terminal postscript eps enhanced mono “Helvetica” 14 set output “my-plot.eps” plot sin(x) This…
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…
To convert a PostScript file to PDF suitable for publishing, use ps2pdf from the Ghostscript suite: ps2pdf -dPDFSETTINGS=/printer file.ps file.pdf The /printer setting produces high-quality output appropriate for publication. Other available quality settings include: /screen — lowest quality, smallest file size /ebook — medium quality, reasonable file size /printer — high quality, suitable for printing…
In computer systems, resources must be balanced across available hardware to maximize performance. The Linux kernel runs migration threads as per-CPU daemons to handle this work. These threads manage task migration between CPUs, CPU hotplug operations, and stop-machine synchronization. You can observe migration threads on any modern system: $ ps aux | grep migration root…