This article walks through the complete Linux kernel path a network packet follows—from the NIC’s DMA and hardware interrupt, through soft‑interrupt handling, NAPI polling, protocol‑stack registration, IP and UDP processing, all the way to the user‑space recvfrom system call—revealing the many hidden steps that make packet reception possible.
This guide compiles the most frequently used Linux commands for file navigation, content viewing, searching, permission handling, text processing, compression, system shutdown, and process management, providing clear syntax examples and practical tips to boost operational efficiency for system administrators.
This guide walks you through downloading, extracting, compiling, and installing Redis from source on Ubuntu, configuring its files and startup scripts, securing the service, enabling automatic boot start, and performing data migration with detailed commands and examples.
This article explains how to use the Unix stream editor sed for line selection, pattern searching, deletion, and substitution, covering basic syntax, regular‑expression tricks, multiple‑command usage, and in‑place file editing with practical command‑line examples.
This article measures the CPU time consumed by Linux process and thread context switches, explains the underlying operations, compares simple token‑passing tests with lmbench benchmarks, and shows how to monitor and interpret switch statistics on a production server.
This article introduces SSH, explains its encryption-based login mechanism, demonstrates basic command syntax, shows practical examples of remote login, local/remote/dynamic port forwarding, remote command execution, and discusses common security concerns such as man‑in‑the‑middle attacks.
This tutorial explains how to update an Ubuntu server, add the ondrej/php PPA, install PHP 8 and its extensions, configure php.ini for both Apache and Nginx, adjust performance settings, and restart services to fully enable PHP 8 on a Linux VPS or cloud instance.
Learn to configure port mapping on both Windows and Linux servers, including enabling packet forwarding, adding and deleting proxy rules, setting up iptables NAT, and testing the setup with curl, using practical examples and a multi‑machine lab environment.
This guide explains what Lynis is, walks through installing it on CentOS 8, and demonstrates how to run full system audits, select specific test groups, and view detailed results, helping administrators harden Linux servers with a free open‑source tool.
This guide explores several powerful yet intimidating Linux commands—including crypt, kill, shred, zombie process detection, at midnight scheduling, and daemon management—explaining their purposes, usage nuances, and safety considerations for system administrators and power users.
This comprehensive guide walks through Linux memory management fundamentals, covering virtual address spaces, physical memory zones, user‑space structures, kernel allocation strategies like the buddy system and slab allocator, and practical commands for inspecting memory usage.
This article introduces cheat.sh, a lightweight command‑line cheat sheet that covers over 58 programming languages, numerous DBMS, and more than a thousand Unix/Linux commands, and explains how to query it with curl, use its CLI client, shell and stealth modes, and integrate it with popular editors.
This guide compiles a comprehensive set of Linux shell commands for deleting zero‑byte files, inspecting processes, checking CPU, memory, disk usage, network load, and other system metrics, plus a collection of useful regular expressions for text processing and validation.
This guide provides a step‑by‑step tutorial on preparing a Linux environment, installing Java, GNOME Desktop, VNC remote access, Chinese language support, downloading and extracting Kettle, configuring its startup scripts, creating desktop shortcuts, and managing essential Kettle configuration files for successful Hadoop ETL development.
Linux uses swapping to move rarely used memory pages to disk, alleviating memory pressure and reclaiming idle memory, but the performance impact of disk I/O can cause latency; this article explains the mechanisms, triggers, and kernel functions behind swapping, including direct reclaim, kswapd, and LRU lists.
This guide provides a concise, alphabetically ordered reference of 35 core Linux (and macOS) terminal commands, complete with explanations, practical examples, and usage tips to help newcomers quickly become comfortable navigating and managing a Unix-like system.
This article explains Linux's cron daemon (crond), its role in system and user task scheduling, how to view and edit crontab files, write cron expressions, manage the crond service, and common commands for listing, locating, and removing scheduled jobs.
Linux swap moves anonymous pages to a dedicated swap area—either a partition or a file—using structures such as swap_info_struct, swap_map and swp_entry_t, with a two‑pass swap‑out, per‑CPU slot cache, and SSD‑focused optimizations like clustering and readahead to improve performance.
The article introduces Huawei's open-source Bisheng JDK 8, outlines its performance‑enhanced features such as JFR and fast serialization, and provides a step‑by‑step installation guide for the Linux/AArch64 platform, including download links, extraction commands, and optional configuration options.
This tutorial provides a complete walkthrough for downloading Hadoop 2.8.2, setting up a three‑node master‑slave cluster, configuring core, HDFS, MapReduce and YARN settings, creating required directories, distributing the installation, starting the services, verifying the cluster status, and finally shutting it down.
After my small 1‑CPU, 2 GB server was compromised by a crypto‑mining virus that hijacked SSH access, I used VNC to investigate, identified malicious processes, traced infected files, removed cron jobs, restored system utilities, repaired SELinux, and closed the Redis vulnerability to fully recover the machine.
This article introduces the three fundamental Linux text‑processing utilities—awk, grep, and sed—explaining their distinct purposes, core functionalities, and typical usage scenarios for searching, editing, and formatting text in command‑line environments.
This guide compiles dozens of practical Linux shell commands for deleting zero‑byte files, inspecting processes, checking CPU, memory, disk usage, and more, plus a collection of useful regular expressions for matching Chinese characters, emails, URLs, IPs, and other patterns.
This article provides an in‑depth tutorial on using the Linux logrotate utility, covering default configuration files, command‑line options, example configurations for services like Nginx, PHP‑FPM, Tomcat, custom Bash and Python rotation scripts, troubleshooting tips, and how to adjust cron scheduling for automated log rotation.
This guide explains how to read and set Linux environment variables, presents multiple methods for configuring the PATH variable—including export, user‑level rc files, and system‑wide files—and details the exact order in which these files are loaded, helping you avoid conflicts and ensure proper persistence.
This article introduces SSH, explains its encryption-based login mechanism, demonstrates basic commands for remote access, details port forwarding (local, remote, dynamic) with practical examples, and discusses common security concerns such as man‑in‑the‑middle attacks.
This guide explains how to configure Linux environment variables—especially PATH—using export commands, editing user and system profile files, and demonstrates the exact order in which Ubuntu loads these files, helping you avoid conflicts and ensure persistent settings.
This article explains the TCP three‑way handshake and four‑way termination processes, clarifies the TIME_WAIT state, shows how to inspect socket states with netstat, and provides practical Linux sysctl settings to reduce excessive TIME_WAIT sockets and improve network performance.
This guide explains how to install tcpdump, use various options such as -nn, port filters, -c, and -w to capture and save network packets, and introduces tshark commands for detailed HTTP traffic analysis on Linux systems.
The article details a MySQL server startup failure caused by insufficient memory, shows command outputs and error logs, and explains how reducing the innodb_buffer_pool_size to 64 MB in the my.cnf configuration resolves the issue on a 2 GB Alibaba Cloud instance.
This article walks through turning an old 2009 laptop into a disk‑less Volumio player by configuring iSCSI network boot, covering BIOS/UEFI basics, PXE/iPXE workflow, MBR vs GPT partitioning, bootloader setup, initrd customization, and troubleshooting tips.
This guide explains multiple methods for configuring Linux environment variables—especially PATH—on Ubuntu, covering user‑level files like ~/.bashrc and system‑wide files such as /etc/profile, and details the exact loading order Linux follows when initializing shells.
This guide shows how to create and use a Bash script called tf that leverages the tree command to display directory structures, supports keyword searching, and explains the color codes used to differentiate file types in the output.
This guide explains how to install the free cross‑platform tool FreeFileSync on Ubuntu 18.04, create a desktop launcher, configure language and settings, and perform bidirectional file synchronization with customizable comparison methods, filters, and sync modes.
This article explains four methods to determine MySQL server startup time, such as checking service status, querying uptime, using ps, and inspecting logs, and also outlines common crash causes like bugs and resource allocation failures, providing troubleshooting steps and diagnostic commands.
This article explains the purpose of TCP's three‑way handshake and four‑way termination, walks through the connection lifecycle, highlights the impact of excessive TIME_WAIT sockets, and shows how Linux sysctl parameters can be tuned to improve network performance.
This article explains how a host discovers and configures PCIe devices through a depth‑first enumeration process, describes the BDF addressing scheme, and illustrates memory‑mapped I/O interactions such as NVMe command submission using Linux lspci commands.
This article presents ten practical Linux system‑administration techniques—from ejecting a stuck DVD drive and resetting a frozen console to using screen sharing, SSH tunnels, bandwidth testing, and powerful command‑line scripts—each designed to streamline tasks, reduce downtime, and give administrators more free time.
This article explains Linux HugePages, how to view and configure them, demonstrates code and Kubernetes examples, and details how larger memory pages reduce management overhead and lock memory to improve performance for memory‑intensive services like databases and Hadoop.
This tutorial explains how to use WeChat's template message API together with the iciba daily‑sentence service, set up a Python script on an Alibaba Cloud Linux server, configure the template in the public platform, and schedule automatic delivery via a daily cron job.
This guide walks you through ten essential Linux command‑line tools—uptime, dmesg, vmstat, mpstat, pidstat, iostat, free, sar, and top—explaining what each metric means, how to interpret the output, and how to quickly spot utilization, saturation, and error issues within the first minute of investigation.
This tutorial explains how to set up port forwarding on Windows using netsh and on Linux using iptables, demonstrates a multi‑machine lab with dual‑NIC servers, and shows how to verify that external clients can reach internal services through the configured mappings.
This tutorial walks you through installing Zsh on Ubuntu 20.04, setting it as the default shell, configuring its initial options, using a quick .zshrc setup, and reverting back to Bash if needed, with all commands and screenshots included.
This guide explains how to install Kibana 7.6.2 on a Linux server, configure its kibana.yml settings, start the service, troubleshoot common permission issues, and access the web interface for visualizing Elasticsearch data in real-time.
This article explains the distinction between kernel space and user space in a 32‑bit Linux system, covering address layout, privilege levels, mode transitions, system calls, and the overall OS structure to illustrate how separating these spaces enhances stability and security.
This guide presents ten practical Linux system‑administration tricks—from unmounting a stuck DVD drive and resetting a frozen console to using screen for collaborative debugging, recovering a lost root password, creating SSH backdoors, tunneling VNC, measuring bandwidth, and automating host‑file generation—helping admins work faster and smarter.
This guide walks you through customizing Nginx 404 error pages, enabling the stub_status module to monitor server metrics, increasing worker processes and connections, adjusting header buffers, and configuring client-side caching for static assets to boost web server performance.
This article compares four classic Linux packet‑capture engines—libpcap (and its mmap variant), PF_RING, DPDK, and XDP—explaining their data‑flow architectures, copy operations, zero‑copy techniques, and typical use‑cases such as DDoS defense and high‑speed networking.
This article explains how to diagnose Linux server network problems using common tools such as ping, a shell script for LAN scanning, traceroute, nslookup, netstat, and telnet, providing command syntax, example outputs, and guidance on interpreting results.
This article provides a comprehensive guide to Ansible, covering its purpose, key features, installation steps, SSH key setup, inventory configuration, core commands, essential modules, playbook syntax, handlers, role structures, and practical examples for automating Linux system administration.
Learn how to enable OpenSSH's Banner option on a CentOS 7 system, create a custom banner file (including ASCII art generated with figlet), and restart the sshd service so every SSH login shows your personalized message.
This guide explains how to use tcpdump on Linux to capture packets, filter by ports, hosts, interfaces or protocols, save output for later analysis, and interpret both human‑readable and hexadecimal dumps, with practical examples and tips for integrating Wireshark.
This guide explains Linux’s file‑permission model, the meaning of numeric chmod codes, and why using recursive 777 is a security risk, then shows how to correctly set ownership and permissions for files and directories to keep web servers safe.
This guide explains how to execute external shell scripts, import their functions and variables using source, dot, or sh commands, compares their behaviors, and provides practical patterns—including case dispatch and a generic function‑call template—to enable reliable script reuse in Linux environments.
This article explains how the Linux top command provides real‑time server monitoring, details its common options, interprets each line of its output—including CPU, memory, and process information—and shows useful interactive commands and a practical example for tracking a specific process.
This tutorial explains how to install Redis on Linux (including source compilation and Docker), set it up as a daemon, install the PHP Redis PECL extension, configure Composer, install ThinkPHP5, and run a simple PHP script that stores and retrieves a value from Redis.
This article provides a comprehensive guide to using iptables for port forwarding, explains the four tables and five chains, details common command syntax, match criteria, actions, additional modules, and includes practical examples for NAT configuration and protecting against small‑scale attacks.
This article introduces essential Ansible terminology such as control node, managed nodes, inventory, host files, modules, tasks, playbooks, and roles, and demonstrates basic commands for user creation, directory management, file deletion, and package handling on Linux hosts.
This article compares four classic Linux packet‑capture engines—libpcap, libpcap‑mmap, PF_RING, DPDK, and XDP—detailing their data‑path architectures, copy‑count reductions, zero‑copy techniques, and typical use‑cases such as DDoS defense and high‑speed trading.
This guide explains how to shrink the /home partition, install missing fuser, resize the filesystem, and expand the root directory on a CentOS/RHEL 7 log server, including commands for unmounting, killing processes, resizing ext4 or xfs partitions, and re‑mounting the filesystem.
The article explains why the Linux find command is preferred over locate for real‑time, precise file searches, outlines its basic syntax, and demonstrates three common usage methods—piping to xargs, command substitution with $(), and the -exec option—complete with example commands and outputs.
This guide explains how to install gdisk on CentOS, create a GPT partition on a new 10 TB data disk, format it, mount it, and set up automatic mounting at boot using the disk's UUID, with step‑by‑step commands and screenshots.
This guide explains how the Linux ss utility provides comprehensive socket statistics—including TCP, UDP, and Unix sockets—offers powerful filtering by state, address, and port, and demonstrates why it outperforms netstat in speed and resource usage through concrete command examples.
This comprehensive guide explains Linux privilege escalation, covering horizontal and vertical privilege upgrades, essential information‑gathering commands, kernel vulnerability exploitation, sudo abuse, SUID/SGID misconfigurations, cron job hijacking, NFS weak permissions, and PATH misconfigurations, with practical examples and code snippets for each technique.
This guide explains how to safely reduce the /home partition size, free up space, and extend the root filesystem on a CentOS 7 server by unmounting /home, locating and terminating lingering processes, resizing the filesystem, installing required tools, and remounting the adjusted partitions.
MySQL startup failures are typically caused by either insufficient system resource access (such as file permissions or security policies) or incorrect configuration parameters, and can be diagnosed by checking permissions, security policies, and the order and content of MySQL option files.
This step‑by‑step guide shows new Linux server users how to configure remote login, switch to fast mirrors, install essential tools like lrzsz and vim, set up environment variables, install Go, and add the vim‑go plugin on a CentOS 8 system.
This guide walks you through removing old MySQL versions, installing MySQL 8.0 via YUM or binary packages, configuring a secure initial password, setting up multiple instances on different ports, and addressing typical MySQL 8.0 pitfalls such as user creation, remote root access, authentication plugins, and character set settings.
This article explains the design of Linux file systems, focusing on ext4's inode layout, block allocation, extents, directory storage, journaling modes, and the kernel's cached and direct I/O paths, complete with code snippets and structural diagrams.
This guide explains how to locate Docker container log files on Linux, provides shell scripts to list and truncate oversized logs, and shows how to configure per‑container and global log size limits using docker‑compose and the Docker daemon to keep host disk usage under control.
This article explains the core design of Linux file systems, covering strict organization, block and inode structures, ext4 formatting details such as extents and meta block groups, directory storage, journaling modes, and the kernel's cached and direct I/O paths for reading and writing files.
This guide explains Linux runlevels, essential systemctl commands, key service directories, and walks through creating an additional SSH service and a custom shell‑based service using systemd, complete with step‑by‑step commands and example unit files.
This guide explains how the Linux tee command reads from standard input and simultaneously writes to both a file and the screen, providing seven detailed examples that cover basic usage, writing to multiple files, silent output, appending, sudo integration, piping between commands, and using tee within vim.
This tutorial walks through checking the default Python version on a Linux system, locating its binaries, downloading Python 3.6.5 source, installing required build dependencies, compiling and installing Python, creating symlinks, and configuring environment variables, while also addressing common network and repository issues.
This article compares Linux's select, poll, and epoll mechanisms, explaining their internal workings, limitations such as FD_SETSIZE and linear scanning, and why epoll's event‑driven design offers superior scalability and performance for high‑concurrency network servers.
This guide walks through diagnosing a mis‑partitioned CentOS 7 log server, installing missing tools, safely unmounting and shrinking the /home XFS filesystem, expanding the root volume, and remounting while emphasizing backup and proper command usage.
This article provides an in‑depth technical guide to Linux, covering its Unix heritage, process and thread creation, kernel architecture, virtual memory, scheduling algorithms, file‑system structures, I/O handling, networking, and built‑in security mechanisms such as user IDs, permissions, and set‑UID features.
This article explains how Docker containers, built on Linux kernel virtualization, provide lightweight isolation, higher resource efficiency, rapid startup, consistent environments, easy migration, and simplified maintenance, and walks through installation, image creation, registry usage, and deployment on Huawei Cloud SWR.
This article explains how the Linux netlink connector, together with a lightweight user‑space ncp program, can audit all process events in real time, enabling detailed host security monitoring, detection of intrusion behaviors such as reverse shells, and reconstruction of attack chains through captured exec, fork, and exit data.
This guide explains how to configure Linux iptables NAT to forward traffic from an external network to multiple internal devices, covering the underlying PREROUTING/DNAT and POSTROUTING/SNAT mechanisms, step‑by‑step command examples, testing procedures, and best‑practice tips.
This article explains what Linux load average actually measures, distinguishes it from CPU utilization, and demonstrates how to interpret and monitor load with practical stress‑test scenarios using tools like uptime, mpstat, and pidstat.
This article explains the core design of Linux file systems, covering strict organization, block allocation, inode structures, ext4 extent trees, block groups, superblock metadata, directory storage formats, and the kernel's cached and direct I/O paths for reading and writing files.
This article introduces ten useful but often overlooked Linux commands—pgrep, pstree, bc, split, nl, mkfifo, ldd, col, xmlwf, and lsof—explaining their purpose, typical use cases, and providing concrete examples to help system administrators work more efficiently.
This comprehensive guide presents essential Linux system commands covering hardware inspection, date handling, shutdown/reboot, file and directory management, searching, mounting, disk usage, user/group administration, permissions, packaging, backup, and network utilities, providing a practical reference for system administrators.
This guide explains why relying on third‑party reverse proxies for JRebel activation can fail, and provides step‑by‑step instructions to build your own local or server‑side reverse proxy, generate the required GUID, and configure IDEA or command‑line activation for seamless hot‑deployment.
This guide walks you through two methods for installing the Exa command‑line tool on various Linux distributions, explains required dependencies, shows step‑by‑step commands for binary and source installations, and demonstrates common usage options with practical examples.
Learn step-by-step how to install the msmtp email client, configure mutt for sending mail, use the free command to monitor Linux memory and swap usage, script automated monitoring and alerting, and schedule these tasks with cron for continuous system health checks.
This guide explains what vnStat is, its key features, and provides step‑by‑step instructions for installing vnStat and vnStati on CentOS, RHEL, Fedora, Debian, and Ubuntu, configuring the service, and using the tools to monitor and graph network traffic on Linux systems.
This guide explains what Terminus is, how to install the .deb package on Deepin 15.11 from GitHub, launch the application, and customize its appearance, hotkeys, plugins, and color scheme, providing a modern, flexible terminal experience for Linux users.
This guide walks you through installing PostgreSQL 12 and the web‑based pgAdmin4 management tool on RHEL 8, covering module selection, database initialization, service configuration, and Apache‑based server‑mode setup with necessary SELinux and firewall adjustments.
This article explains the five Linux I/O models—blocking, non‑blocking, I/O multiplexing, signal‑driven, and asynchronous—detailing their system calls, synchronization concepts, performance characteristics, and how they map to Java BIO, NIO, and AIO implementations.
This guide explains Linux's cron daemon, its configuration files, permission controls, how to write and install crontab scripts, and provides numerous scheduling examples, helping administrators automate tasks efficiently, including command syntax, special characters, and common service commands.
This guide explains why terminal enthusiasts need a visual resource monitor, introduces bpytop, and provides step‑by‑step instructions for installing it via source, package managers, or snap on various Linux distributions, plus usage tips and configuration details.
This article explains the fundamentals of the Domain Name System, demonstrates how to use the dig tool to view detailed query processes, explores DNS record types, hierarchical lookups, root servers, and additional utilities like host, nslookup, and whois, providing a comprehensive guide for developers and network engineers.
This article explains Linux's file system architecture, covering basic directory structures, absolute and relative paths, symbolic links, the Virtual File System layer, core system calls such as creat, open, read, write, lseek, locking mechanisms, and the design of ext2, ext4, /proc, and NFS file systems.
This guide compiles the most useful Unix/Linux commands for PostgreSQL administrators, covering background execution, mail queue handling, email with attachments, file searching, cleanup, compression, diffing, remote synchronization, timestamp‑based file moves, and system reboot techniques.
This tutorial explains the Linux chmod command, covering the permission model, how to view permissions with ls -l, numeric and symbolic notations, recursive changes, reference files, and multiple practical examples to help you manage file and directory access securely.
Learn how to run multiple Linux commands on a single line using the semicolon, &&, and || operators, with clear syntax explanations, practical examples, and tips for controlling execution flow based on success or failure.
This article explains how to create and use Kickstart answer files for fully automated RHEL 8 installations, covering each directive, package selection, and the steps to add the Kickstart path to both BIOS/Legacy and UEFI boot menus, complete with example code.
This tutorial explains the Linux chmod command, covering permission basics, how to view permissions with ls‑l, numeric and symbolic modes, recursive changes, reference files, and special cases like applying execute rights only to directories, all with clear examples and command syntax.
