This step‑by‑step guide shows how to create a highly available Nginx load‑balancing cluster with Keepalived in both master‑slave and dual‑master configurations, covering server preparation, Nginx and Keepalived setup, VIP handling, testing, and a watchdog script to ensure service continuity.
Learn how to install and use the powerful MTR network diagnostic tool across Windows, Linux, macOS, and Android, explore its key parameters and options, and interpret its detailed reports to identify packet loss and latency issues for effective network troubleshooting.
This article explains how a simple read of a single byte in user space triggers a complex Linux I/O stack involving the read system call, VFS, page cache, generic block layer, and I/O scheduler, and clarifies when actual disk I/O occurs and how many bytes are transferred.
This guide shows how to locate every .git directory within a few levels, trim the paths, and run git pull on each repository using a single pipeline command that can also be saved as a convenient shell alias.
This article provides a comprehensive, hands‑on tutorial for preparing three VMs, installing JDK and Hadoop, configuring core‑site.xml, hdfs‑site.xml, mapred‑site.xml, yarn‑site.xml, setting environment variables, distributing the package, starting HDFS and YARN, and verifying the cluster via web UI and jps commands.
This article provides a comprehensive tutorial on Redis Cluster, covering its architecture, data partitioning and redundancy, step‑by‑step instructions for downloading, compiling, and installing Redis on CentOS, as well as detailed procedures for manually or automatically creating a six‑node cluster with master‑slave replication and slot allocation.
This guide walks through manually adding a new Linux user named zhangsan on CentOS 8 by editing /etc/passwd, /etc/shadow, and /etc/group, creating the home directory, setting proper ownership and permissions, creating a mail file, and verifying the account.
This guide walks you through installing Keepalived via yum or source, explains the main configuration sections—including global definitions, VRRP instances, and virtual servers—and details each directive’s purpose, enabling you to set up reliable high‑availability load balancing on Linux systems.
This tutorial walks you through installing MySQL 5.7 on two CentOS 7.6 machines, configuring the master and slave my.cnf files, setting up replication users, starting the services, and verifying synchronization with detailed commands and troubleshooting tips.
This guide shows how to create a lightweight, recursive file‑search script for Linux that mimics the Windows Everything tool, explains each part of the shell code, and demonstrates how to run it, enable case‑sensitivity, search specific paths, and bind it to a custom alias.
This guide walks through enabling the Windows Subsystem for Linux, installing Ubuntu (or other Linux distributions) from the Microsoft Store, creating a user, updating packages, and installing Go tools, with step‑by‑step screenshots and command examples for developers on Windows 10.
This guide compiles essential MySQL security steps, master‑slave replication principles, backup scripts, Linux boot overview, common port services, virus mitigation, monitoring tools, nginx optimization, InnoDB lock troubleshooting, replication lag reduction, high‑availability components, data migration utilities, and automation configuration management techniques for operations engineers.
This article provides a comprehensive introduction to Docker, covering its origin, core concepts, application scenarios, differences from physical machines and virtual machines, installation steps, essential commands, container lifecycle management, Dockerfile creation, image customization, registry publishing, and a practical Flask example.
This article explains how Linux formats disks using mkfs, detailing block size, inode and block counts, block groups, directory structures, and how to choose appropriate parameters for different workloads to achieve optimal storage efficiency and performance.
This comprehensive guide covers over 100 essential Linux interview questions, detailing system overview, kernel components, file system hierarchy, shell scripting, common commands, security practices, and troubleshooting techniques to help candidates master Linux fundamentals and ace technical interviews.
This comprehensive guide compiles over 100 essential Linux interview questions, covering fundamentals, system architecture, command-line tools, security practices, scripting, file management, networking, and performance tuning for job interviews.
This guide details practical hardening techniques for Linux and Windows servers, covering SSH configuration, password policies, account lockout, su restrictions, ICMP suppression, firewall rules, RDP port changes, security policies, and disabling vulnerable services to significantly improve system security.
The article explains how directories consume inodes and filesystem blocks, how this consumption grows with many files or long filenames, and why the ls command can become sluggish, offering practical tips to mitigate the performance impact.
This tutorial provides a beginner-friendly, step-by-step walkthrough for downloading, installing, configuring, and verifying Prometheus, Node Exporter, Alertmanager, and Grafana on a Linux server, including service setup, configuration files, and a simple alert test.
This guide explains how to install JDK 8, Android SDK Tools, and Gradle on a Linux system, including downloading packages, extracting them, configuring environment variables, verifying installations, and using sdkmanager to list, install, or uninstall Android platform packages.
This comprehensive guide introduces Ansible's core concepts, architecture, and key features, then walks through installation, inventory configuration, command usage, module options, playbook creation, handlers, and role-based organization, providing practical examples and code snippets for effective automation across Linux and mixed environments.
This guide shows Linux administrators how to copy files while excluding specific files or directories using three common utilities—cp, scp, and rsync—by demonstrating practical command‑line examples and the necessary syntax for selective transfers.
This article shows how to calculate the sum of all even numbers from 1 to 1000 using Linux shell scripts, presents two implementations (a while‑loop and a for‑loop with seq), compares their execution time, and explains useful seq options for generating numeric and character sequences.
Learn how to locate exact package names on Ubuntu and Debian using apt‑cache, apt search, and aptitude, including updating the repository index, filtering results, viewing package details, and installing the discovered packages.
This article details a step‑by‑step investigation of excessive native memory usage in a Spring Boot service, explaining how JVM tools, system tracers, and custom allocators revealed that the default MCC package scanner and Inflater implementation caused a hidden memory leak that was fixed by configuring scan paths and upgrading Spring Boot.
This article explains how ulimit settings can cause hidden failures across SysVinit, Systemd, and container environments, details common pitfalls such as PAM overrides and Debian-specific bugs, and provides step‑by‑step solutions and troubleshooting tips to ensure reliable limit configurations.
This guide explains why you might need a private cloud, compares several open‑source solutions, and provides step‑by‑step instructions—including Docker installation and Nextcloud deployment—so you can quickly set up a multi‑device synchronized cloud storage on a CentOS 7 VPS.
This step‑by‑step guide shows how to set up a personal blog on a CentOS 7.7 server with Hexo, configure Git, SSH keys, and a GitHub repository, then deploy the site to GitHub Pages and optionally bind a custom domain.
This article explains how to inspect and clear Linux memory buffers, interprets the fields shown by the free command, and then dives into SQL join types, performance‑impacting factors such as join_buffer_size, and practical optimization techniques like indexing and denormalization.
This guide walks you through purchasing a VPS, installing DNF, Apache, PHP, and MariaDB on CentOS 8, configuring SELinux, deploying Nextcloud from source, setting permissions, and completing the web‑based setup, enabling a fully functional self‑hosted cloud storage service.
This article explores whether creating an empty file with the touch command consumes disk space on Linux, revealing that each empty file uses one inode and a small amount of directory block space, and explains inode structures, related commands, and a real‑world inode exhaustion incident.
This guide presents practical Bash scripting techniques—including strict mode, file locking, graceful termination, timeout handling, and pipeline debugging—to help developers write more robust, maintainable, and error‑resilient shell scripts for automation and system tasks.
This article provides a comprehensive, hands‑on tutorial for installing and configuring Ceph as the backend storage for OpenStack, covering network planning, host setup, password‑less SSH, repository configuration, ceph‑deploy commands, pool creation, and integration with Glance, Cinder, and Nova services.
This roundup covers Tencent Cloud's first domestic serverless PostgreSQL database, GitHub's free core features for all users, the nginx 1.17.10 release with a new auth_delay directive, a COBOL programmer's urgent call, and upcoming Linux dual‑boot on iPhone, among other tech headlines.
Meituan’s DBA team discovered that Intel Skylake CPUs dramatically increased PAUSE‑instruction latency, causing MySQL’s ut_delay spin‑wait loops to consume most CPU cycles and reduce write throughput, and they restored performance by back‑porting MySQL 8.0’s spin_wait_pause_multiplier patch to 5.7, upgrading to CentOS 7, and moving to Cascadelake hardware.
This guide walks you through creating a PHP extension, covering environment setup, using phpize, configuring, compiling with make, installing the shared test.so module, adding it to php.ini, and verifying its functionality with command‑line tests, preparing you for production deployment.
This guide explains how to hide an application from Ubuntu's Dash by locating its .desktop file, copying it to the local applications directory, editing the file to set Hidden=true, and then logging out and back in to apply the change.
This guide walks you through ten practical steps—including switching to local yum mirrors, installing key packages, disabling SELinux and the firewall, trimming startup services, tightening SSH settings, syncing time, raising file descriptor limits, and disabling ping—to boost the performance and security of a freshly installed Linux server.
This article explains why naïve Docker images can balloon to gigabytes, then walks through multi‑stage builds, language‑specific trimming techniques, and the use of minimal base images such as scratch, showing how to reduce image size from over a gigabyte to just a few megabytes while preserving developer and operations convenience.
Microsoft's latest Windows 10 build lets users open the Linux subsystem's root directory straight from File Explorer, offering a penguin icon shortcut, command‑line access via \\wsl$, and guidance on safe usage while highlighting upcoming full‑kernel integration.
This guide walks through essential Linux shell commands covering process termination, system shutdown and reboot, echo usage, Vim editing shortcuts, file copying, moving, compression, searching with find and grep, as well as interpreting and modifying file permissions and ownership.
This article introduces essential terminal commands and practical scenarios for macOS users, covering tools like man, grep, tail, awk, top, lsof, ansible, and nc, and offers efficiency tips such as aliases, plugins, and fuzzy finders to boost productivity.
This tutorial explains the Linux cut command, covering its syntax, key options such as -f, -d, -b, -c, --complement and --output-delimiter, and provides numerous real‑world examples for extracting fields, characters, and bytes from text files and combining cut with other Unix utilities.
This article explains Linux’s layered filesystem architecture, detailing how generic API calls like read interact with the VFS, superblock, inode, dentry, and buffer cache, and demonstrates mounting a filesystem using loop devices, dd, losetup, mke2fs, and mount commands.
Learn how to use the free YUMI (Your Universal Multiboot Integrator) tool to create a multi‑boot USB drive that can hold multiple Windows, Linux, and WinPE ISO images, covering installation steps, usage tips, and removal of unwanted systems.
This article explains why mechanical hard drives are slower and less reliable than electronic components, introduces RAID 0, RAID 1, and RAID 5 as solutions to improve speed and fault tolerance, discusses RAID card caching, and shows practical Linux commands for examining RAID hardware and configuration.
This article explains the layered architecture of Linux file systems, how generic API calls like read operate across different storage media, demonstrates creating and mounting loop‑back file systems with dd, losetup, mke2fs and mount commands, and details the core VFS structures such as superblock, inode, dentry and buffer cache.
The article explains the design and operation of Linux’s BFQ (Budget Fair Queueing) I/O scheduler, its algorithmic advantages over CFQ, performance test results, and the reasons it outperforms other schedulers, concluding with its growing adoption in major projects.
This guide explains how to install, configure, and use the open‑source os_monitor tool to collect CPU, memory, and disk metrics, store them in MySQL, and trigger email or WeChat alerts through a web dashboard with simple SQL‑based setup.
This guide explains how to use tcpdump’s command‑line options, build powerful filter expressions, and provides dozens of practical examples for capturing and analyzing network packets on Linux systems.
This article presents eleven practical Linux terminal techniques—including essential keyboard shortcuts, sudo shortcuts, background job handling, nohup, at scheduling, man page tweaks, htop, ranger, shutdown cancellation, process killing, and YouTube video downloading—to help users work faster and manage their systems more efficiently.
This article explains the hierarchical storage pyramid, Linux kernel I/O stack, page‑cache synchronization policies, the atomicity of write operations, the role of mmap and Direct I/O, and how disk characteristics influence multithreaded read/write performance and design decisions.
This article provides a comprehensive overview of core networking concepts, including the OSI seven-layer model, TCP/IP three-way handshake and four-way termination, DNS resolution process, HTTP request workflow, intra- and inter-subnet data transmission, Linux network configuration, and practical troubleshooting techniques for common connectivity issues.
This tutorial walks through pulling the Redis Docker image, creating configuration files, running the container, connecting with redis-cli, testing commands, enabling persistence, and installing a visual management tool, providing complete step‑by‑step instructions for Docker‑based Redis deployment.
This tutorial explains how to download the MySQL Docker image, create and run a MySQL container with volume mappings and environment variables, verify the container, connect to the database via Workbench, and access the container’s shell and host files.
This guide explains why and how to copy production traffic to a pre‑release environment, walks through installing Nginx, configuring the ngx_http_mirror_module, building Nginx from source with the module, and provides useful commands and documentation links.
This article walks through a real‑world Linux server compromise, detailing the symptoms, forensic commands, rootkit discovery, attack vector via an Awstats vulnerability, and provides a comprehensive recovery checklist for securing the system.
Discover ten handy but often overlooked Linux commands—pgrep, pstree, bc, split, nl, mkfifo, ldd, col, xmlwf, and lsof—each explained with clear descriptions and practical example usages to boost your command‑line efficiency.
This article explains how to use Linux commands like free and sync to view and clear buffer/cache memory, describes the information shown by free, and then dives into SQL join types, their performance impact, and optimization techniques such as indexing, join_buffer tuning, and join algorithms.
This article explains the physical makeup of mechanical hard drives—including platters, heads, tracks, cylinders and sectors—shows how to view disk details with Linux commands like lsblk and fdisk, and clarifies common misconceptions about heads, cylinders and sector sizes.
This article explains what Linux zombie processes are, why the kernel retains them after a program exits, the crucial information they store, and demonstrates how to create, observe, and properly clean up zombies using C code and standard system calls.
This guide walks through preparing a CentOS 7.5 environment, installing GNOME and xrdp for remote desktop access, and then downloading, uploading, and executing the QQ for Linux installation script, culminating in launching the client and logging in via QR code.
This article provides a comprehensive guide to tuning Linux kernel parameters and NGINX configuration directives—such as backlog queues, file descriptors, worker processes, keepalive settings, access log buffering, sendfile, and limits—to achieve optimal web server performance for high‑traffic sites.
This tutorial explains how to delete a user from one or multiple Linux groups using the usermod and gpasswd commands, as well as by manually editing the /etc/group file, with step‑by‑step examples and complete command output.
This article explains why traditional server and service monitoring (e.g., Zabbix) may miss business outages, then walks through setting up Nagios on Debian to monitor web page URLs, API health checks, and related services, including configuration files, plugins, and a desktop alert tool, Nagstamon.
This article explains the concept of inodes, their contents, size, numbering, relationship with directories, hard and soft links, special behaviors in Unix/Linux, and provides a real‑world troubleshooting example for inode exhaustion.
This tutorial explains how to install Supervisor on CentOS and Ubuntu, configure its main and program-specific files, and use it to monitor a continuously running Python script, automatically restarting the script if it crashes or is killed.
This article explains what a process is, distinguishes it from a program, outlines its key characteristics, describes how multiple processes are created, and covers special cases such as orphan and zombie processes, termination methods, process groups, sessions, and race conditions in operating systems.
This article explains why nohup cannot monitor scripts, introduces Supervisor as a Python‑based process monitor, shows how to install it on CentOS, Ubuntu, and via pip, details the supervisord.conf and program .ini configurations, demonstrates a sample Python script, and outlines common commands for managing and restarting services.
This guide explains what the MySQL Test framework is, how to set up the required environment on Ubuntu, install dependencies and MySQL source, configure and compile the test suite, and demonstrates creating and running a simple test case with detailed command‑line examples.
This article compiles a comprehensive list of resources—including tools, scripts, and tutorials—for conducting interface performance testing on Linux and other platforms, covering topics such as netdata localization, timewatch utility, load testing strategies, JVM heap dumps, and visualizing test data.
This guide explains how to use Netcat—a tiny, versatile TCP/UDP utility—to test ports, transfer files, measure bandwidth, and even create simple backdoors, covering both GNU and OpenBSD versions with concrete command examples for Linux and Windows environments.
If you enable automatic login on Ubuntu or other Linux distributions, you may repeatedly see prompts to unlock the login keyring, especially when using browsers that store passwords, and this guide explains the keyring concept, its security role, and step‑by‑step methods to change or disable its password.
This tutorial walks you through enabling the Windows Subsystem for Linux, installing Ubuntu from the Microsoft Store, configuring the new Linux environment, updating packages, and adding Go tools, providing clear screenshots and command examples for a smooth cross‑platform development setup.
Learn how to efficiently update root passwords across dozens or hundreds of Linux servers by creating Expect scripts that automate SSH logins, parse IP and password lists, and execute batch password changes, complete with step-by-step instructions, required environment setup, and script explanations.
This tutorial explains LVM snapshot principles, walks through preparing a logical volume, creating and mounting snapshots, handling common XFS UUID errors, restoring data manually or via snapshot merge, and provides practical commands and images for each step.
This step‑by‑step guide shows how to check current disk usage, add a 60 GB disk, create a physical volume, extend the volume group and logical volume, resize the filesystem, and verify the root partition expansion on a CentOS 7 server.
This article explains why Linux administrators need flexible storage, introduces Logical Volume Manager (LVM), details its core concepts, walks through installation, creation of physical volumes, volume groups, logical volumes, formatting, mounting, and provides step‑by‑step procedures for expanding and shrinking LVM volumes on both ext4 and XFS filesystems.
This guide walks you through installing the Mailx email client on a Linux server, applying necessary patches, configuring SMTP settings, testing email delivery, and creating a shell script that monitors log files for keywords and automatically sends alert emails when matches are detected.
This article explains Linux user and group management, detailing the structure of /etc/passwd and /etc/shadow, user classifications, commands for creating, viewing, modifying, and deleting users, as well as password handling and related security considerations.
This guide explains multiple practical methods for discovering which ports are open on a Linux system, covering Nmap scans, Netcat probing, and Bash pseudo‑device checks, complete with command examples, option details, and output interpretation.
This guide walks you through fast, practical techniques for discovering which network ports are open on a Linux system using Nmap, Netcat, and Bash pseudo‑devices, helping you secure your server and troubleshoot connectivity issues.
This article introduces BPF/eBPF fundamentals, explains the bcc toolkit, provides installation steps for Ubuntu and CentOS, and demonstrates how to use bcc's dbstat and dbslower utilities to trace MySQL query latency and slow queries on Linux systems.
This article explains CPU fundamentals, the difference between physical and logical cores, how to query CPU details on Linux, the meaning of CPU utilization and load average, and provides practical steps for diagnosing high user‑mode CPU usage, especially in Java applications.
This guide walks through preparing a CentOS 7.6 host, generating self‑signed certificates, installing Docker CE, configuring a Docker registry mirror, downloading and installing Harbor, and demonstrates how to push, scan, sign, and pull images while troubleshooting common issues.
This article explains how Linux memory statistics (free, top) report buffer/cache usage, how to clear it with sync and drop_caches, and then dives into SQL join concepts, types, optimization techniques, and MySQL join algorithms such as nested loop and block nested loop, highlighting their impact on performance.
This article walks you through building an OpenStack Stein cloud on a single host using Kolla, covering environment preparation, Docker and Ansible setup, configuration files, password generation, deployment commands, and final login verification, all with detailed code snippets and images.
This article explains how Linux kernels receive network packets—from NIC hardware interrupts through NAPI polling, kernel TCP/IP processing, and finally to user‑space sockets—while also covering interrupt handling, buffer tuning, and performance‑optimizing techniques for SREs.
This comprehensive guide covers essential Linux fundamentals, common interview questions, and practical server administration techniques, including boot sequences, runlevels, file system differences, process management, packaging tools, Nginx optimization, MySQL replication, Docker usage, and useful shell scripts for real‑world operations.
The Linux block layer, positioned between the VFS and device drivers, evolved from a single‑queue design to a multi‑queue architecture (kernel 3.13 onward) to reduce lock contention and exploit modern hardware queues, managing bio/request lifecycles, dispatching through layered queues, and employing various I/O schedulers for balanced throughput and latency.
Learn how to quickly locate, filter, and rename files on Linux using concise ls, find, du, and rename commands, plus practical examples that cut down search time, reveal the largest items, count directory contents, and automate batch renaming.
This guide walks you through installing Mailx on a Linux server, fixing compilation issues, configuring SMTP settings, testing email delivery, and building a keyword‑based log‑monitoring script that triggers alerts via email.
This article explains the complete computer boot sequence—from BIOS initialization and MBR loading to the GRUB boot loader, kernel startup, initramfs handling, run‑level scripts, and finally the login prompt—providing a clear, step‑by‑step overview of each stage.
This article compiles essential shell‑script guidelines—shebang usage, commenting, parameter validation, variable handling, indentation, naming conventions, encoding, permissions, logging, security, line continuation, quoting, modular main functions, scope control, return values, indirect references, heredocs, path resolution, brevity, parallel execution, and search tricks—to help you write maintainable and performant Bash scripts.
This guide presents a comprehensive cheat sheet of essential Linux commands, covering online queries, file and directory management, content viewing, compression, information display, file searching, user and permission handling, network operations, disk and filesystem tasks, system monitoring, shutdown/reboot procedures, and process management.
This article compiles a set of high‑resolution Linux mind maps covering learning paths, desktop overview, filesystem hierarchy standards, critical directories, kernel roadmap, security coaching, command references, and cheat sheets, providing direct links to the original sources for deeper study.
This article provides a comprehensive guide to the Linux top command, explaining its default output, system uptime, load averages, task summary, CPU and memory usage, field columns, interactive shortcuts, and command‑line options for customizing real‑time process monitoring.
This tutorial walks through preparing a CentOS 7.5 host, installing required dependencies, creating an nginx user, downloading the source, compiling and installing Nginx 1.11.1, configuring the firewall, and using common Nginx commands to start, test, reload, and enable the service at boot.
This article humorously compiles a variety of command‑line tricks—from simple process killing to Docker container shutdown and even a Python one‑liner—to force‑quit Vim, while also offering tongue‑in‑cheek “violent” and “Zen” approaches for developers who struggle with the editor's steep learning curve.
This guide explains how to use Netcat—a lightweight, versatile TCP/UDP utility installed on most Linux distributions—for port scanning, connectivity checks, UDP sessions, file transfers, bandwidth measurement, and even creating simple backdoors, while highlighting differences between GNU and OpenBSD versions.
