This guide walks you through using Linux's two main firewall tools—firewalld for CentOS 7+ and iptables for older versions—covering installation, service control, rule management, port handling, and useful commands with clear examples and screenshots.
This guide introduces the Duc tool for visualizing Linux disk usage, covering its supported interfaces and databases, step‑by‑step installation on Debian‑based systems and from source, core commands for indexing and querying, and how to generate terminal and graphical visualizations.
This guide introduces fifteen entertaining Linux command‑line tools—including sl, fortune, cowsay, cmatrix, figlet, toilet, oneko, xeyes, yes, cal, shred, factor and more—providing installation steps, usage examples, options and screenshots so you can add playful effects to any terminal session.
This guide compiles the most useful Linux commands for service control, file handling, compression, disk and network monitoring, and package management on CentOS 7.6, providing clear examples and visual references to help developers and sysadmins work efficiently.
This guide walks you through practical Linux performance troubleshooting steps, covering how to inspect CPU details, list boot‑time services, monitor CPU load, check free memory, and analyze disk I/O, with concrete commands and solutions to improve system speed.
This article explains common scenarios that lead to accidental directory or file deletions in Linux shell scripts—such as empty variables, spaces in paths, special characters, and failed cd commands—and provides practical Bash techniques like variable expansion checks, quoting, set -u, logical short‑circuiting, and safer prompts to avoid catastrophic rm -rf mistakes.
Learn how to install CRIU on CentOS, create a simple Node.js program that prints its PID, capture its state with a checkpoint using CRIU, and then restore the process, demonstrating practical use cases like migration and fast startup.
This guide introduces a collection of practical Linux operations tools—including Nethogs, IOZone, IOTop, IPtraf, IFTop, HTop, NMON, MultiTail, Fail2ban, Tmux, Agedu, NMap and Httperf—providing concise installation commands, basic usage examples, and key options to help system administrators monitor performance, security and resources efficiently.
This article outlines the origins of UNIX, its trademark evolution, major branches such as BSD, System V, and the various commercial UNIX-like systems—including Mac OS X, AIX, Solaris, HP‑UX, IRIX, Xenix, A/UX—and the rise of Linux and its many distributions.
This article introduces Linux Virtual Server (LVS), explains its three‑tier architecture, details its main components and three load‑balancing methods (NAT, IP Tunneling, Direct Routing), compares their performance, and reviews the eight scheduling algorithms used for traffic distribution.
Linus Torvalds, the creator of Linux, began programming at age 11, built the OS inspired by Minix and Unix, leveraged community support, and exemplifies traits such as intense focus, modesty, and dedication, offering valuable lessons for developers and highlighting the historical evolution of open‑source operating systems.
This article traces two decades of Chinese operating system development—from early Linux initiatives like Red Flag Linux to carrier‑backed mobile platforms and Alibaba's YunOS—examining technical, market, and policy factors that could determine whether a home‑grown OS can achieve mainstream success.
The article analyzes write latency caused by a slab lock in the monitoring agent, evaluates kernel upgrades and BIOS power‑saving settings, and explains CPU power‑state mechanisms (P‑States, C‑States, T‑States) with performance testing scripts to guide server performance tuning.
This article explains how Linux kernels 2.6 and 4.18 manage CPU power‑saving P‑states and C‑states, compares energy‑saving and performance modes, and details the underlying idle drivers, BIOS settings, and performance impacts on Intel Xeon E5‑2630 v4 CPUs.
This article reproduces a Linux 4.18 kernel scenario to analyze why CPUs remain in C0 under power‑saving mode, examines the role of the tuned service and hyper‑threading, and provides concrete BIOS and tuned‑service configuration recommendations for different workload profiles.
This article explains how Linux pipes transmit data in real time, explores buffering modes, demonstrates practical experiments with Python scripts, and details read/write rules, including SIGPIPE handling, providing developers with essential insights for effective command-line pipeline usage.
This guide walks you through Docker fundamentals, its container‑based virtualization, installation on Windows and Ubuntu, architecture components, image concepts, and a hands‑on workflow that covers pulling, running, building, and pushing images, all illustrated with clear examples and diagrams.
This article explains the step‑by‑step boot sequence of a computer—from the BIOS reading the MBR on the selected storage device, through the boot loader loading the kernel, to the kernel initializing hardware, spawning the init process, and finally presenting the login screen.
This article explains the fundamentals of Linux control groups (cgroups), their components and hierarchy rules, and demonstrates how to create, configure, and apply cgroups for resource limiting in containers using shell commands, Docker, and Kubernetes.
The article examines write latency problems caused by a monitoring agent's slab lock in older Linux kernels, explores kernel upgrade and agent modification solutions, and details how BIOS power‑saving settings and CPU power‑state management (P‑States, C‑States, T‑States) affect server read and compute performance.
This article explains how Linux kernels 2.6 and 4.18 manage CPU P‑states and C‑states, covering BIOS control, cpupower usage, idle drivers, the menu governor, MONITOR/MWAIT effects, and performance comparisons between power‑saving and performance modes on Intel Xeon E5‑2630 v4.
This guide introduces a dozen practical Linux operation tools—including Nethogs, IOZone, IOTop, IPtraf, IFTop, Fail2ban, Tmux, and others—providing concise descriptions, download links, and ready‑to‑run installation commands to help system administrators boost monitoring, performance testing, and security on their servers.
This comprehensive guide introduces Docker’s origins, core concepts such as images, containers, and registries, explains installation on major platforms, demonstrates essential commands, shows how to run and manage containers, and walks through creating, tagging, pushing, and importing custom images using Dockerfile.
This article analyzes write latency caused by slab locking in older Linux kernels, evaluates kernel upgrades and BIOS power‑state settings, and explains CPU power‑management mechanisms (P‑States, C‑States, T‑States) that affect storage read/write performance.
This tutorial walks you through preparing a CentOS 7.4 system, installing MariaDB, setting up Zabbix 3.4.6 with MySQL support, configuring the database and web frontend, and finally starting all services to achieve a fully functional monitoring platform.
Learn how to use the netcat (nc) command together with simple shell scripts to efficiently check whether one or multiple ports are open across a list of servers, eliminating manual checks and speeding up network diagnostics for both single‑port and multi‑port scans.
This guide explains what Anbox is, how to install it on various Linux distributions using snap, PPA or AUR, sets up required kernel modules and ADB, and shows step‑by‑step how to download APKs and install Android apps like YouTube and Firefox inside Anbox.
PacVim turns learning Vim commands into a fun Pac‑Man‑style game, offering easy installation, level‑based challenges, and instant feedback so beginners can master the editor through interactive play.
This article introduces Linux‑command, a comprehensive, searchable reference covering over 540 Linux commands with syntax, options, and examples, helping developers quickly recall and master command‑line tools while highlighting its popularity, features, and visual interface.
This article explains the fundamentals of Linux Cgroups, their role in container resource isolation, how to create and manage hierarchies, control groups, and subsystems, and demonstrates practical usage with Docker and Kubernetes for CPU and memory limits.
This article compiles a comprehensive list of practical Linux GUI and command‑line tools—including launchers, editors, system utilities, networking, and development helpers—to improve workflow efficiency and assist users in selecting the right applications for their needs.
This guide walks you through manually assigning an IP address to a CentOS 6.7 virtual machine by editing the network script, enabling boot, disabling the firewall, restarting the network, and verifying connectivity, enabling further tasks like building distributed clusters.
This article compiles a comprehensive set of Linux commands, JVM utilities, and Java debugging tools—including tail, grep, awk, find, tsar, btrace, greys, JProfiler, jps, jstack, jmap, jstat, and IntelliJ plugins—to help engineers quickly diagnose, monitor, and resolve production issues while optimizing performance.
This guide introduces 29 core Linux command‑line utilities—such as ls, mkdir, cp, grep, and tar—explaining their basic syntax, common options, and typical use cases, providing newcomers and system administrators with a concise reference for everyday tasks.
This article walks through common Linux boot failures and provides step‑by‑step solutions using single‑user mode, GRUB command editing, and the Linux rescue environment, including password recovery, disk sector fixes, GRUB configuration errors, and dual‑boot restoration techniques.
This guide walks through disabling SELinux and the firewall, installing and configuring OpenLDAP server, setting up the phpLDAPadmin web console, adjusting Apache and phpLDAPadmin settings, and verifying the LDAP service on a CentOS system.
This article explains the five Linux I/O models—blocking, non‑blocking, I/O multiplexing, signal‑driven, and asynchronous—using a fishing metaphor, shows how Java’s BIO/NIO/AIO map to OS mechanisms, and clarifies why most of them are still synchronous despite different implementations.
This article walks through the complete journey of a single Java statement—from high‑level source code, through compilation to bytecode, JVM interpretation and JIT compilation, down to CPU instruction fetching, decoding, execution, caching, memory hierarchy, threading, interrupts, and the underlying Linux process model.
Learn step‑by‑step how to identify an unmounted 160 GB disk on a Linux server, create the necessary LVM partitions, extend the volume group and logical volume, and resize the filesystem—all without rebooting—using commands such as df, fdisk, pvcreate, vgextend, lvextend, and xfs_growfs.
The article analyzes the growing demands on network I/O, explains Linux and x86 bottlenecks, introduces DPDK’s user‑space bypass architecture and its core optimizations such as hugepages, poll‑mode drivers, SIMD, and CPU‑specific tuning, and finally discusses the DPDK ecosystem and practical considerations for backend developers.
This guide walks you through essential Linux performance diagnostics—checking CPU details, boot‑time services, CPU load, free memory, and disk I/O—providing concrete commands, interpretation tips, and practical solutions to identify and resolve common slowdown causes.
In a candid 25‑year follow‑up interview, Linus Torvalds and Robert Young discuss Linux’s evolution, development philosophy, future outlook, hardware choices, open‑source culture, and advice for young developers, while also tracing Young’s entrepreneurial journey from early ventures to his current projects.
This comprehensive guide explains what Docker is, its key concepts, advantages, installation steps, essential commands, container lifecycle, image customization with Dockerfile, registry usage, and practical examples for building and deploying containerized applications on Linux.
After a quarter‑century since his first interview, Linus Torvalds and Robert Young discuss Linux’s evolution, development philosophy, hardware choices, the future of the kernel, open‑source culture, and advice for young programmers, offering candid insights into the project's past, present, and outlook.
This guide outlines the career stages, skill sets, and practical tasks for DevOps engineers—from entry‑level troubleshooting to senior‑level architecture, automation, and performance optimization—providing concrete learning paths, tools, and personal development advice to help engineers advance their operations careers.
This tutorial walks you through installing Bitcoin Core 0.18 on a Linux server, covering prerequisite packages, downloading and extracting the source code, building Berkeley DB, configuring and compiling the client, creating a configuration file, and starting or stopping the daemon.
This article explains how Linux pipes transmit data in real time, why output may appear delayed due to buffering, how to control buffering with flush or large writes, and what the SIGPIPE signal means when a pipe’s read end is closed.
This guide shows how to configure rc.local‑style startup commands on Ubuntu 16.04 by editing /etc/rc.local directly, and on Ubuntu 18.04 by linking the systemd rc‑local.service, creating an executable rc.local file, adding shell commands, and verifying the result after reboot.
This article explains a whimsical comic that visualizes the Linux kernel as a multi‑layered house, detailing the foundation of file cabinets, the process table, key system processes like init, cron, Apache and SSH, the role of TTY terminals, and related Linux concepts.
This article explains the limitations of traditional disk partitioning, introduces Linux's Logical Volume Manager (LVM), details its core concepts and workflow, and shows step‑by‑step how to create, extend, and use logical volumes for flexible storage management.
This guide outlines a step‑by‑step career roadmap for operations engineers, covering early‑stage tasks, essential Linux and networking skills, intermediate responsibilities like clustering and monitoring, and senior‑level challenges such as large‑scale automation, containerization, performance tuning, and security hardening.
This guide walks you through restoring a Linux system when essential files like /lib64/libc.so.6 are accidentally deleted, using the rescue mode to copy missing libraries back and reboot the system successfully.
This article provides a comprehensive overview of operating systems, covering their definition, core components, historical evolution, classifications, key functions, the GNU/Linux ecosystem, licensing models, versioning schemes, major distributions, package managers, and the role of Linux in modern computing environments.
This comprehensive guide demystifies the Linux ps command by explaining its option syntax, the differences between BSD, SYSV and GNU styles, record‑selection rules, sorting, threading, field selection, modifiers, and error‑handling, while providing practical examples, visual illustrations, and tips for effective system monitoring.
After years of legal battles over VMware's use of GPL‑licensed Linux code in its ESXi hypervisor, developer Christopher Helwig has abandoned his appeal, citing the court's high evidentiary demands and VMware's recent pledge to stop using Linux code.
This article explains the meaning of the Linux uptime/top output, defines system load average as the average number of runnable and uninterruptible processes, distinguishes it from CPU utilization, and provides guidance on interpreting load values for single‑core and multi‑core systems.
This guide walks readers through Docker fundamentals, covering both operations and development perspectives, including installing Docker, managing images and containers, executing commands, connecting to running containers, building images from Dockerfiles, and deploying simple web applications on Linux and Windows environments.
This article explains the fundamentals of SSH, covering its purpose, architecture, password and key authentication methods, how to verify installation and service status, and practical commands for connecting, transferring files with scp, and using sftp on Linux systems.
This article provides an in‑depth overview of TCP congestion control, covering the sliding‑window flow control, the congestion control state machine with its five states, and the four core algorithms—slow start, congestion avoidance, fast retransmit, and fast recovery—plus practical insights for middleware design.
This guide explains Linux's three‑level permission model (owner, group, others), how to view file attributes with ls, and how to change owners, groups, and access rights using chown, chgrp, and chmod in both symbolic and numeric forms.
The Linux 4.20 kernel series has reached its final release with version 4.20.17, and maintainer Greg Kroah‑Hartman urges users to migrate to the newer 5.0 series or a supported LTS kernel, outlining the series' features, hardware support, and upgrade paths.
This article explains the evolution of Linux device management, introduces udev’s architecture and key features, details rule file syntax and operators, and provides practical examples—including disabling VXLAN offload, setting I/O scheduler, and enabling SR‑IOV—complete with command‑line snippets.
This comprehensive guide introduces Docker’s origins, core concepts such as images, containers, and registries, walks through installation, daemon configuration, essential commands, building and managing images, running containers interactively or in background, and explains import/export, tagging, and repository usage, providing practical examples throughout.
This guide introduces five Android apps that let you write, compile, and run C/C++, Java, Python, front‑end web, and Linux code on a smartphone, with installation steps, key features, and screenshots to help beginners start mobile programming quickly.
This guide details the prerequisites, multiple deployment methods (WAR, macOS, Windows, Linux), and post‑installation configuration steps for Jenkins, including unlocking the instance, installing plugins, creating an admin user, setting an update site, and configuring a slave node.
This guide presents a comprehensive visual cheat sheet of essential Linux commands, covering file and directory operations, content viewing, compression, information display, file searching, user and permission management, basic and advanced networking, disk and filesystem handling, system monitoring, shutdown/reboot, and process management.
This guide provides concise explanations and practical examples for the most commonly used Linux shell commands—including ls, cd, pwd, mkdir, cp, mv, rm, du, df, cat, echo, less, head, tail, wc, grep, man, logout, pipes, xargs, basename, dirname, and set—helping beginners quickly become proficient with the command line.
This article explores Linux kernel memory management in depth, covering process address space layout, allocation mechanisms, OOM killer behavior, the whereabouts of allocated memory, and both manual and automatic memory reclamation techniques.
This comprehensive guide introduces the most frequently used Linux commands, covering directory navigation, file manipulation, permission management, searching, compression, system shutdown, and network utilities, providing clear syntax examples and explanations to help users efficiently manage and troubleshoot Linux systems.
When upgrading a Linux OS on a Dell PowerEdge C6420 via UEFI, the Mellanox 25G network adapter disappears from Device Settings, and this guide walks you through using the Mellanox Firmware Tools to enable the NIC with detailed commands, screenshots, and hardware requirements.
This guide walks through practical Linux commands—including xargs, background execution, resource monitoring, multitail, continuous ping logging, netstat analysis, and SSH port forwarding—to help sysadmins write concise scripts, troubleshoot performance, and automate routine tasks effectively.
This article provides a comprehensive introduction to container technology as a PaaS solution, explaining Docker's core principles, the role of Linux namespaces and cgroups, comparing containers with virtual machines, and discussing both the advantages and limitations of container-based deployments.
This guide explains how to enable status modules for Nginx, MySQL and PHP‑FPM, write Bash monitoring scripts, configure Zabbix agent user parameters, create Zabbix templates, add items, triggers and graphs, and verify monitoring of all components including the Zabbix server itself.
This article introduces Linux regular expressions, explains the two types of metacharacters—shell and regex—shows how to enable colored output with grep, provides a sample test file, and demonstrates numerous practical pattern-matching examples ranging from simple word searches to complex character class and repetition constructs.
This article compiles a comprehensive set of Linux operations interview questions and answers, covering topics such as the definition of ops, server management, RAID configurations, load‑balancing solutions, middleware, MySQL troubleshooting, scripting tasks, network diagnostics, and best‑practice optimizations for high‑pay sysadmin roles.
This guide walks you through 35 practical examples of the Linux find command, covering name‑based searches, permission filters, owner/group criteria, date ranges, size limits, and deletion techniques, helping sysadmins efficiently locate and manage files and directories.
Linux Kernel 5.0, recently released after seven release candidates, brings modest enhancements such as AMD open‑source GPU driver updates, FreeSync support, a new perceptual scheduler for ARM big.LITTLE power management, Adiantum encryption for low‑power devices, Btrfs swap, UDP GRO, cgroupv2 cpuset, and binderfs for multiple Android instances, alongside numerous driver additions and bug fixes.
This article explains how PCIe devices are discovered and accessed in an x86 system, detailing the hierarchical bus topology, depth‑first enumeration steps, configuration space handling, Linux lspci inspection, and NVMe command transmission through PCIe memory transactions.
This guide walks you through installing Scala 2.11.7 on macOS/Linux and Windows, covering prerequisite Java setup, downloading the binary, configuring environment variables, and verifying the installation with command‑line checks.
Linus Torvalds, born in Helsinki in 1969, created the Linux kernel in 1991 after experimenting with MINIX and writing his own disk driver, championing free software principles that now power billions of devices—from servers to Android phones—while his controversial personality sparked intense community debates.
This article provides a step‑by‑step tutorial on installing and configuring KVM on a Linux server, covering CPU virtualization enablement, package installation, module loading, network setup, virtual disk creation, VM deployment, firewall rules, and VNC access.
This article explains the 2019 Alibaba Cloud IO HANG incident, defines IO HANG, and provides step‑by‑step guidance on using the Linux commands top, iostat, and iotop (including examples and key options) to monitor and troubleshoot server disk I/O performance.
This guide walks through creating a local CentOS Yum repository from an ISO image, backing up the default repo files, mounting the ISO, configuring a local repo, switching to Aliyun or 163 mirrors, setting repository priorities with yum‑plugin‑priorities, and testing package installation to ensure the local source is used first.
The article shares a developer’s experience interviewing at over 30 Chinese tech firms, breaking down three main interview focuses—data structures and algorithms, operating‑system and core‑technology knowledge, and project experience—while also offering practical advice on networking questions, open‑source tools, and how to evaluate a company's interview process.
The article shares the author’s interview experiences at over 30 companies and provides a comprehensive guide covering data‑structure and algorithm questions, core C++ concepts, operating‑system fundamentals, networking protocols, open‑source tools, project‑experience expectations, and practical advice for evaluating both technical and non‑technical aspects of potential employers.
This tutorial walks you through preparing a CentOS 7.4 system, installing MariaDB, setting up Zabbix 3.4.6 (including repository configuration, package installation, database creation, and web front‑end), adjusting PHP settings, and finally starting and enabling all services for a fully functional monitoring platform.
This article explains Linux process management fundamentals, covering process concepts, lifecycle, threads, priorities, context switches, interrupt handling, process states, memory layout, and the O(1) CPU scheduler, providing clear diagrams and practical insights for developers and system engineers.
This article explains the Linux load average metric, the run queue structure, why both running (R) and uninterruptible (D) processes are counted, and how the kernel uses an exponential weighted moving average to compute the 1‑, 5‑, and 15‑minute load values.
This guide walks you through Linux command‑line shortcuts, the five key system‑operation metrics, and powerful tools like smem, ps, and sort to efficiently monitor CPU, memory, processes, disks, and network while also handling zombie processes.
This article provides a collection of practical Linux and Windows system‑administration Q&A, covering software installation and removal, remote connection tools, IP and hostname configuration, backup scripts, iptables rules, MySQL security and replication, network utilities, and various shell command examples.
This guide explains both basic and advanced usages of the Linux mv command, covering options like -v for verbose output, -i for interactive prompts, -n to prevent overwriting, -u to update only newer files, and -b to create backups before replacement.
This tutorial walks through setting up Nginx on Debian to serve static files, reverse‑proxy dynamic requests to Tomcat, configure load‑balancing upstreams, enable gzip compression, implement on‑disk and memory caching, and secure the server with SSL, providing full configuration examples and practical tips.
This article provides an in‑depth exploration of the NVMe over Fabrics protocol, detailing its design goals, data encapsulation scheme, IO transmission process, command extensions such as Connect and Property Get/Set, and the associated Linux reference implementation for RDMA and Fibre Channel transports.
Arm announced its upcoming Neoverse N1 platform and E1 CPU, sparking a heated debate with Linus Torvalds over ARM versus x86 server dominance, while developers like antirez argue for ARM's growing viability in server and cross‑development scenarios.
This tutorial walks you through preparing a CentOS 7 system, installing MariaDB, setting up Zabbix 3.4.6 with all required packages, configuring the database and web front‑end, and finally launching the monitoring service, complete with code snippets and screenshots.
Drawing from interviews at over thirty tech firms, this article breaks down the three main interview tracks—data structures and algorithms, operating‑system fundamentals, and project experience—while also sharing practical advice on evaluating companies, handling non‑technical questions, and navigating the hiring process.
This article explains what Linux load average is, how the kernel’s run‑queue (including R and D state processes) is used to compute it via an exponential weighted moving average, and how to interpret the resulting metrics for system performance.
This guide walks you through 35 practical examples of the Linux find command, covering name searches, permission filters, owner/group queries, date‑based queries, and size‑based searches, each illustrated with clear explanations and screenshots to help sysadmins and developers locate files efficiently.
This article shares a Linux operations engineer's interview experience, detailing the job requirements, seven common interview questions with thorough answers on self‑introduction, gray releases, MongoDB deployment, Jenkins CI/CD, Tomcat modes, monitoring solutions, and data backup strategies, plus practical interview tips.
This article explains how Linux manages processes and threads, describes the creation and lifecycle of processes, the role of the process control block, the causes and handling of zombie processes, and compares multi‑process and multi‑threaded designs, providing practical tips for avoiding common pitfalls.
