This guide introduces HAProxy, an open‑source L4/L7 load balancer, and walks through its core features, performance and stability characteristics, step‑by‑step installation on CentOS 7, configuration of both L7 and L4 balancing, monitoring, and setting up high‑availability with Keepalived.
The article explains how the MySQL "Can't create a new thread (errno 11)" error on SLES12SP5 was diagnosed as a TaskMax limit issue and resolved by increasing the system‑wide DefaultTasksMax or setting a per‑service TasksMax, followed by a MySQL restart to apply the changes.
This article explains how Linux system and user resource limits—such as file descriptors, stack size, and process counts—can cause runtime failures, demonstrates practical experiments to modify these limits via ulimit, /etc/security/limits.conf, and prlimit, and provides guidance for stable server-side programming.
This guide explains how to achieve high availability for Nginx by deploying a dual‑machine keepalived setup, covering the concepts of HA, VRRP, configuration of keepalived on master and backup nodes, a health‑check script, and step‑by‑step commands to test automatic failover.
This article explains the two types of Linux huge pages—static HugeTLB pages and dynamic Transparent Huge Pages—detailing their sizes, performance advantages, drawbacks, especially for Oracle workloads, and provides step‑by‑step instructions for checking status and permanently disabling THP via sysfs or GRUB.
This article explains how Linux manages disks and filesystems by detailing the roles of inodes and dentries, the structure of filesystem storage, the Virtual File System layer, various I/O classifications, and practical commands for observing filesystem performance and cache usage.
This tutorial shows how to activate IPv6 support for Docker bridge networks by obtaining a public IPv6 block, dividing it into subnets, configuring the Docker daemon, restarting the service, and optionally setting up IPv6 in Docker Compose, with full code examples.
An in‑depth guide walks through essential Linux server monitoring tools—top, vmstat, pidstat, iostat, netstat, tcpdump and others—explaining each command’s output, key metrics, and how to interpret CPU, memory, disk and network statistics for effective troubleshooting and performance tuning.
Learn how to replace manual rc.local startup scripts with elegant solutions using Crontab's @reboot feature and Systemd services, including step‑by‑step commands and advanced scheduling tricks for reliable automatic execution after a reboot.
This guide explains how to use the built‑in Logrotate tool on Linux to configure automatic log rotation, customize rotation policies for services like Nginx, PHP and syslog, troubleshoot common issues, and replace ad‑hoc scripts with reliable, cron‑driven solutions.
This article explains why zero‑copy techniques such as mmap, sendfile and DMA dramatically reduce CPU copies and context switches in traditional read/write I/O, improving the performance of high‑throughput systems like RocketMQ and Kafka.
This guide explains how to use the Linux split command to divide large files into smaller parts and the cat command to concatenate those parts back together, including syntax, practical examples, and help options for efficient file transfer and management.
This article explains the fundamentals of IO events and IO multiplexing, compares thread‑based and event‑driven models, details the Reactor pattern variants, and discusses synchronous versus asynchronous IO, providing a practical guide for building high‑performance network frameworks in Linux.
This article explains how attackers and administrators can use Linux shell commands and a custom script to view, modify, save, and restore file timestamps, thereby concealing forensic evidence of unauthorized activity on a server.
This guide walks you through installing kkFileView on Windows and Linux, integrating it with MinIO for online file preview, configuring Docker containers, and customizing settings such as watermarks, providing step‑by‑step instructions and code snippets for a seamless preview service.
This guide explains what cron timers are, how to create cronjobs using the crontab command, the syntax of cron expressions—including fields for minute, hour, day, month, and weekday—as well as shortcut macros, and how to edit or stop scheduled jobs on Linux.
The article explains how to analyze core‑dump files with GDB by examining the function call stack, key registers, and memory contents, classifying crash causes, using GDB commands to inspect variables and addresses, reconstructing corrupted stacks, handling optimized‑away data and vtable errors, and following a systematic debugging workflow.
This article explains the various timer implementations—sorted linked list, min‑heap, balanced binary tree, and especially the hierarchical timing wheel used in the Linux kernel—detailing their time complexities, data structures, and the core C code that inserts and executes timers efficiently.
The article details a step‑by‑step investigation of a MySQL server that ran out of memory due to massive slab cache consumption by inode and dentry objects, showing how Linux commands, scripts, and cache‑dropping techniques resolved the issue and revealed the root cause of excessive partition tables.
This article explains the meaning of each CPU usage field shown by the top command, dives into the Linux kernel source that records these metrics via clock interrupts, and shows how the percentages are computed from /proc/stat data.
This article provides a step‑by‑step Bash script for installing, configuring, and starting MySQL 8.0 on a Linux system, including user creation, directory setup, permission handling, initialization checks, and service management, and ensures proper environment variables.
This guide explains how to install GNU Screen, start and name sessions, manage multiple windows with keyboard shortcuts, detach and reattach safely, and customize settings via .screenrc, ensuring long‑running tasks persist across SSH disconnections.
This article introduces a collection of Linux command‑line utilities—such as nload, iftop, iptraf, nethogs, bmon, and many others—that can monitor overall and per‑process network bandwidth, explain their measurement methods, and provide installation instructions for major distributions.
The article reports on recent Chinese tech news—from massive travel‑card queries and ByteDance layoffs to Douyin’s remote‑work policy and a new partnership between Taobao and QQ Music—while spotlighting BC‑Linux V8.2, a CentOS‑compatible OS with dual kernels, performance boosts, and enhanced security.
This guide walks you through searching, installing, updating, and removing software on Linux using the apt and dnf package managers, covering command syntax, regex searches, group installations, and how each tool handles caches and configuration files.
This guide explains how to use the HDFS shell (preferred via hdfs dfs) to list, copy, move, delete, and snapshot files in a Hadoop cluster, detailing command syntax, URI handling, generic options, and practical examples for each operation.
This article explains TCP’s connection establishment and termination processes, details the roles of half‑ and full‑connection queues in Linux, demonstrates how to simulate and detect queue overflows using tools like netstat, ss, hping3 and ab, and provides kernel tuning parameters to mitigate SYN flood and TIME_WAIT issues.
Linux swap extends virtual memory by moving infrequently used pages to disk, and this guide explains what swap is, its pros and cons, sizing recommendations for various RAM amounts, how to create and manage swap partitions or files, and performance tuning tips including swappiness and I/O optimization.
This article provides a detailed reference of essential Linux commands covering file manipulation, system monitoring, user and permission management, networking, compression, and system control, offering a practical guide for administrators and developers to efficiently operate and maintain Linux environments.
This tutorial walks through downloading and extracting Prometheus, configuring a MySQL exporter, launching Prometheus, installing Grafana, adding a Prometheus data source, installing the Zabbix plugin, and restarting services to build a complete monitoring stack on Linux.
This guide explains how the Linux history mechanism works, shows essential commands for viewing, filtering, and replaying past commands, demonstrates timestamping, adjusting record limits, changing the history file, disabling logging, and shares a hidden trick for keeping sensitive commands out of the log.
This guide explains three methods to automatically execute scripts after a Linux system boots—using the traditional /etc/rc.local approach, the @reboot option in crontab, and creating a dedicated Systemd service—providing step‑by‑step commands and examples for each technique.
This guide explains when to use Linux alias commands, how to create temporary and permanent aliases, list and verify them, remove unwanted ones, and provides practical examples for simplifying commands, changing behavior, and accessing shortcuts, helping users streamline their shell workflow.
This article details the background, goals, design decisions, deployment steps, kernel tuning, fault‑recovery testing, performance optimization, and TPCH benchmark results of a Greenplum data‑warehouse cluster expansion, highlighting practical challenges and concrete solutions for large‑scale database environments.
The article explains CPU utilization and CPU load, clarifies time‑slice concepts, distinguishes user‑mode and system‑mode usage, describes how load reflects the average number of runnable and waiting tasks, and provides Linux commands and troubleshooting steps for high‑load/low‑utilization and vice‑versa scenarios.
This guide shows three reliable ways to run custom scripts automatically after a Linux machine boots—by editing /etc/rc.local, using a crontab @reboot entry, or creating a dedicated systemd service—along with example commands and advanced timing options.
This guide explains the difference between standard Huge Pages and Transparent Huge Pages in Linux, outlines the performance benefits and drawbacks of using Huge Pages, and provides step‑by‑step commands and GRUB configuration methods to safely disable Transparent Huge Pages on CentOS systems.
This guide compiles a comprehensive set of Linux commands, Java troubleshooting utilities, JVM options, and IDE plugins that help developers diagnose performance issues, resolve jar conflicts, and monitor production systems efficiently.
This guide reviews a collection of Linux command-line utilities that let you track overall and per‑process network bandwidth, display inbound and outbound traffic separately, and generate real‑time or historical usage reports, helping administrators quickly identify bandwidth‑heavy processes.
Learn how to install and use the powerful MTR network diagnostic tool across Windows, Linux, macOS, and Android, understand its combined ping/traceroute output, master key command-line options, and interpret loss, latency, and stability metrics to effectively troubleshoot connectivity issues.
This article provides a comprehensive guide to iptables, covering its underlying netfilter architecture, the five built‑in chains and tables, rule syntax, common match and target options, and practical command examples for adding, deleting, querying, and managing firewall rules on Linux systems.
This article explains the fundamentals of Linux virtual memory, covering its origin, paging and page tables, memory addressing, the role of swap, common questions about 32‑bit vs 64‑bit systems, and practical commands for monitoring and configuring virtual memory on Linux.
This guide explains Linux inode basics, the differences between hard and symbolic links, their creation commands, limitations, and practical scenarios such as version switching, library management, shortcuts, file classification, shared editing, and space‑efficient backups.
This tutorial explains how to use the Linux date command to show the current time, format dates in various ways, query past or future dates, customize output with format specifiers, set the system clock, and incorporate date values into shell scripts.
This guide walks through installing Docker CE on a CentOS 7 system, covering prerequisite kernel checks, repository configuration, package installation, verification with hello‑world, common troubleshooting, and clean removal steps, while explaining core Docker concepts such as images, containers, and registries.
This article explains core operating‑system concepts such as processes, threads, their control blocks and contexts, details how CPU, process, and thread context switches and system calls work on Linux, and shows how to analyze them with vmstat, pidstat, and sysbench for performance tuning.
This tutorial walks you through the Linux kernel source layout, required build tools, cross‑compilation setup, how to compile a kernel image, generate device‑tree blobs, build standalone .ko modules, and integrate those modules into a custom kernel for ARM boards.
This article shares a personal experience with the Deepin Linux distribution, covering its graphical interface, file manager, development environment, communication apps, Android app support, and the many practical advantages that make Linux a viable alternative to Windows for everyday use.
This guide shows Windows users how to quickly access a Linux environment using the built‑in WSL feature, Cygwin, and MinGW, providing download links, installation screenshots, and tips for configuring Python and other tools without heavy virtual machines.
This guide introduces Helix, a modern Rust‑written terminal text editor that leverages Tree‑sitter for fast syntax highlighting and multiple‑selection editing, and provides step‑by‑step instructions for installing it on Arch‑based systems via AUR or on other Linux distributions using Cargo.
This article explains the complete kernel‑level implementation of the TCP three‑way handshake, covering server listen queue allocation, client connect state handling, SYN/SYN‑ACK processing, syncookie protection, timer management, socket creation, and the accept path, with detailed code examples.
Learn to quickly pinpoint Linux server bottlenecks by running ten powerful commands—uptime, dmesg, vmstat, mpstat, pidstat, iostat, free, sar, and top—within a minute, interpreting their outputs using the USE method to assess utilization, saturation, and errors across CPU, memory, disk, and network resources.
This guide explains how to configure and manage Linux disk quotas on XFS file systems, covering prerequisites, quota activation options, user/group/project quota modes, command‑line procedures, testing scenarios, and common operational commands for administrators.
This guide explains how to use grep's powerful options such as -v, -w, -e, -E, --exclude-dir, and --exclude to filter out specific words, patterns, and directories, providing clear command examples for precise text searching in Unix-like environments.
This tutorial explains how to use the ipvsadm command to create and manage LVS/NAT and LVS/DR load‑balancing clusters on Linux, covering command syntax, environment setup for director and real servers, ARP tuning, rule persistence, and extended exercises for HTTP, HTTPS, and MySQL traffic.
This guide shows how to use basic Linux commands such as wc, tr, fold, sort, and uniq to create a text file from a manual page, then extract and rank the most common words and characters, handle case sensitivity, remove punctuation, and filter long uncommon words.
F2 is a fast, safe Go‑based command‑line tool for batch renaming files and folders on Linux, macOS, and Windows, offering multiple installation methods, preview mode, undo, conflict resolution, built‑in variables, and powerful regex‑driven rename examples.
This guide explains how Linux aliases work, shows how to create temporary and permanent shortcuts for long commands like rsync, demonstrates listing and removing aliases, and provides step‑by‑step instructions for storing aliases in ~/.bashrc or a separate file.
This article explains what k3s is, why it’s named that way, and provides detailed, command‑line instructions for installing k3s on a master node, adding worker nodes, verifying the cluster status, and inspecting running containers, all with example outputs and a link to the official documentation.
This article explains iptables fundamentals, its table and chain architecture, common command syntax with practical examples, and demonstrates how iptables is leveraged in Kubernetes and Istio Service Mesh to intercept and redirect pod traffic for advanced service‑mesh capabilities.
Zero‑copy I/O minimizes data copying by using DMA and kernel mechanisms such as mmap + write or the sendfile() system call, with sendfile achieving true zero‑copy through fewer system calls, context switches, and memory copies compared to traditional read/write paths.
This comprehensive tutorial walks you through Linux fundamentals, covering VMware installation, network configuration, essential command usage, user management, software installation methods, shell scripting basics, process management, cron jobs, and awk text processing, all illustrated with step‑by‑step screenshots and code examples.
The article explains that CentOS 8 will cease maintenance next year, ending the free RHEL rebuild, introduces CentOS Stream as a rolling‑release bridge between Fedora and RHEL, and outlines the impact on CentOS 7 and the need to consider alternative distributions.
This tutorial walks through preparing three Linux VMs, disabling firewalls and swap, configuring sysctl, installing Docker and Kubernetes components, initializing the master node, joining worker nodes, deploying the Flannel CNI plugin, creating a test nginx pod, and accessing it via a NodePort service.
This article explains NUMA architecture with hyper‑threading, details CPU cache hierarchies and access latencies, and provides Linux tools and practical optimization techniques to improve cache‑hit rates and minimize cross‑NUMA memory delays.
This comprehensive guide walks you through Docker fundamentals, compares containers with virtual machines, explains core concepts, shows step‑by‑step installation, image building, container execution, and best practices, enabling you to containerize and deploy web applications efficiently.
This comprehensive tutorial explains how to enable and configure Linux Disk Quota on XFS filesystems, covering prerequisites, quota modes, user and directory limits, grace periods, testing scenarios, and essential administration commands for effective storage management.
This guide explains NUMA memory hierarchy, shows how to install and use the numactl command, interprets hardware and NUMA statistics, and presents memory allocation strategies to improve performance on multi‑node Linux systems.
The Linux community announced the first release candidate of the 5.14 kernel, featuring contributions from about 1,650 developers, over 13,000 commits, new memfd_secret system call, extensive driver and architecture updates, and numerous core subsystem enhancements.
This guide explains why large files often need to be split on Linux for network transfer, demonstrates how to use the split command with various options and examples, and shows how to recombine the pieces efficiently using the cat command.
This article explores the IPVS kernel load‑balancing mechanisms, detailing ten built‑in connection scheduling algorithms, introducing a dynamic‑feedback load‑balancing strategy that adjusts server weights based on real‑time metrics, and explains how to compute aggregate load and weight adjustments to achieve optimal scalability and transparency.
This guide explains how to install the Go‑based Ascii Image Converter on Linux, use it to transform JPEG, PNG, BMP, WEBP, or TIFF files (or URLs) into monochrome or colored ASCII art, and customize output size, character sets, and saving options.
This guide explains the NFS (Network File System) protocol, its reliance on RPC, the ports it uses, how to activate the required daemons, differences among NFSv2/v3/v4/v4.1, and provides step‑by‑step instructions for installing, configuring, and mounting NFS on CentOS 7, including firewall and export settings.
This article introduces systemd as the modern Linux init replacement, explains its key features and unit file syntax, and provides three hands‑on examples showing how to manage nginx, Tomcat, and a custom JAR service with systemd commands and configuration files.
This article outlines practical shell‑script guidelines for automating system and application operations, covering script header conventions, formatting, error handling, safe use of commands, variable handling, file packaging, pipeline restrictions, concurrency locks, logging, and risk‑mitigation strategies to make automation both efficient and secure.
This article explains the inner workings of the Linux netstat command, walks through reading /proc/net/tcp and related files, demonstrates how to map sockets to processes, and provides a complete Go implementation of a lightweight netstat utility with code examples and detailed parsing logic.
This article provides a comprehensive introduction to Docker, explaining how Linux containers isolate processes, how Docker packages applications and dependencies into portable images, and why Docker simplifies environment management, version control, sharing, and deployment for modern cloud‑native workflows.
This comprehensive guide explains the architecture and working principles of Linux Virtual Server (LVS), details its NAT, DR, TUN, and FULLNAT modes, explores session persistence techniques, reviews ten scheduling algorithms, and compares LVS with Nginx for high‑performance load balancing.
Learn six effective ways to execute Linux commands in the background—including using &, bg, nohup, output redirection, disown, and tmux—so you can keep working in the same terminal or close it without stopping long‑running tasks.
This article dives deep into the Linux kernel implementation of the listen system call, explaining how the kernel creates and initializes the full‑connection and half‑connection queues, how backlog and system parameters interact, and why these steps are essential before a server can accept client connections.
The article introduces the command‑line utility q, explains how to install it on Linux and Windows, and demonstrates using familiar SQLite‑style SQL queries to search, filter, join, and aggregate log files and command output, offering a convenient alternative to traditional shell tools.
This article explores why a server must call listen() before accept() by dissecting the Linux kernel's listen system call, its interaction with socket objects, and how the kernel calculates and initializes the full and half‑connection queues based on backlog and system parameters.
This article explains why binding a process to a specific CPU improves cache performance, shows how to set CPU affinity on Linux using the sched_setaffinity system call, and walks through the kernel's internal implementation—including run‑queue structures, migrate_task, and __migrate_task—illustrated with code and diagrams.
This article explains the purpose of the TCP TIME-WAIT state, the scenarios it protects against, common misconceptions, and practical Linux kernel tweaks—such as fast recycle, socket reuse, and tw_buckets settings—to manage TIME-WAIT efficiently on high‑concurrency servers.
This article provides a comprehensive introduction to the fundamentals of x86 Linux, covering the historic Intel 8086 processor, segment descriptors, main memory organization, registers, bus architecture, CPU addressing modes, control mechanisms, and the basic instruction execution cycle.
This article introduces Linux cluster fundamentals, explains key concepts such as scalability, high availability, load balancing, and error recovery, categorizes clusters into high‑availability, load‑balancing, and high‑performance types, and outlines common architectures, technologies, and implementation methods for building robust, fault‑tolerant systems.
This guide explains why database backups are essential, walks through creating a backup directory, writing a mysqldump shell script, compressing the dump, granting execution rights, and scheduling the script with cron to run every minute.
This comprehensive tutorial walks through preparing the environment, configuring yum repositories and hosts, installing Oracle Grid Infrastructure with ASM disk groups, creating ASM disks, and finally building an Oracle database on a CentOS 7 system, including command examples and GUI steps.
This tutorial explains what Nushell is, lists the required development packages, and provides detailed commands to download, extract, and install the latest Nushell binaries and plugins on Ubuntu/Debian, RHEL‑based Linux, macOS, and Fedora, plus how to set it as the default shell for a new user.
This article explains why Linux uses virtual IRQ numbers, describes the irq_domain framework and its data structures, compares linear, tree, and no‑mapping strategies, and walks through the complete interrupt‑mapping process on an ARM64 platform with code examples.
This article provides a practical guide to tuning Linux kernel parameters and NGINX configuration directives—such as backlog queues, file descriptors, worker processes, keepalive connections, access‑log buffering, sendfile, limits, caching and compression—to achieve optimal web server performance for high‑traffic sites.
This article explains what Linux load average actually measures, distinguishes it from CPU utilization, describes runnable and uninterruptible states, and demonstrates its behavior through CPU‑intensive, I/O‑intensive, and high‑process‑count scenarios using common monitoring tools.
This guide explains how to install the ngx_http_geoip2 module, upgrade Nginx, configure GeoIP2 databases, and modify the Nginx configuration to block requests from foreign IP addresses, providing step‑by‑step commands and example code for a Linux server.
This comprehensive tutorial explains DNS fundamentals, common record types, essential command‑line tools, BIND installation, zone file creation, master‑slave replication, reverse zones, sub‑domain delegation, forwarding, view‑based responses, and compiling BIND from source, providing a full roadmap for setting up reliable DNS services on Linux.
This guide walks through a collection of frequently used Linux shell commands—grep, custom alias shortcuts, pwd, find, history, od, and for loops—explaining their common scenarios, key options, example usages, and handy tricks to boost productivity in everyday development and scripting tasks.
Learn how to use the Linux ulimit command to inspect and modify both hard and soft resource limits, understand the meaning of limit values such as hard, soft, and unlimited, and apply temporary or permanent changes via command line or the limits.conf file.
Understanding Linux load average and CPU utilization, this guide explains process states, how load is calculated, the difference between load and CPU usage, common bottlenecks, and step‑by‑step troubleshooting techniques using tools like top, vmstat, pidstat, iostat, and perf.
The article explains why Linux newcomers should embrace the command‑line interface, highlighting benefits such as easier troubleshooting, remote SSH access, richer toolsets, essential server management, structured syntax, and shortcuts, while also showing how to open a terminal and start using it effectively.
This guide presents 27 practical Linux command-line techniques—from safe file deletion and alias management to process monitoring, log handling, and advanced shell shortcuts—designed to help heavy users work more efficiently and avoid common pitfalls.
A recent GitHub disclosure reveals that a long‑standing polkit vulnerability (CVE‑2021‑3560) enables unprivileged local users on many Linux distributions to obtain root privileges with just a few commands, prompting urgent updates for affected systems such as RHEL, Fedora, Debian and Ubuntu.
