This guide introduces Docker fundamentals, explains how containers differ from virtual machines, walks through installing Docker on Linux, and demonstrates practical steps to pull and run a MySQL container, while also providing a handy reference of common Docker commands for managing containers and images.
This article compiles an extensive Python reference covering Python 2 vs 3 differences, essential and advanced libraries, concurrency models, language internals, testing techniques, design patterns, data structures, algorithms, networking basics, MySQL and Redis insights, Linux I/O models, and performance‑optimization strategies, all illustrated with practical code snippets.
In a candid interview at the Linux Foundation Open Source Summit, Linus Torvalds and Verizon open‑source lead Dirk Hohndel discuss the Linux kernel's release cadence, security patching, the delayed integration of Rust, and Torvalds' cautious view of AI's role in software development.
This guide explains the FTP protocol, its dual‑channel architecture, active and passive modes, and provides step‑by‑step instructions for installing vsftpd on Linux, configuring ports, time, chroot, logging, user restrictions, anonymous, local, and virtual user setups, plus common client tools.
This guide explains the differences between the su and sudo commands, how to create test users, switch between them using login and non‑login shells, employ the -c option, configure sudo privileges via /etc/sudoers, and choose the safest method for privilege escalation on Linux systems.
Learn how to use the Linux 'ln' command to create and manage hard and symbolic links, understand their differences, and follow step‑by‑step examples for creating, modifying, and deleting links, including useful options and backup handling.
This article explains what RAID (Redundant Array of Independent Disks) is, details the most common RAID levels, compares their performance and fault‑tolerance characteristics, and provides step‑by‑step Linux commands for creating, testing, and managing RAID arrays.
This article outlines the eight critical competencies—from Linux scripting to cloud‑native automation—that define the skill ladder for operations professionals and explain why mastering them is essential for career advancement and higher performance.
This guide walks you through installing NTP, configuring server restrictions, adding a local clock backup, setting log parameters, and synchronizing Linux clients, complete with command examples and troubleshooting steps to ensure accurate network time across your infrastructure.
Linus Torvalds merged a kernel patch that modifies the 64‑bit copy_from_user() implementation to avoid the slow barrier_nospec() call, achieving a 2.6% performance improvement in the "will it scale" benchmark and will be included in the upcoming Linux 6.12 stable release.
This guide introduces the Linux shell, explains how to view and set the current shell and hostname, customize the command prompt, differentiate internal and external commands, manage aliases, use common utilities, handle sessions with screen and tmux, and employ advanced echo formatting and safety deletion techniques.
This guide explains what network‑card promiscuous (promisc) mode is, why it matters for receiving packets across different subnets, and provides step‑by‑step Linux commands and a C program example to enable, disable, and verify the mode on an interface.
This guide lists the most dangerous Linux ports, explains their typical uses, the security risks they pose, and provides concrete recommendations—such as changing default ports, disabling services, and applying firewall rules—to harden your system against attacks.
This article provides two Bash scripts: one that recursively renames all ".sh" files to ".shell" and deletes their second line, and another that repeatedly checks the top‑20 IPs on port 80, reports activity when the smallest request count exceeds 500, or retries after 600 seconds.
This guide walks through a real‑world deployment issue where one node failed to start due to a full disk, showing how to verify overall and per‑directory disk usage with df and du commands, interpret their output, and locate large files or directories.
This article explains the Linux kernel architecture, breaks it into three layers and five key subsystems—process scheduling, memory management, virtual file system, network interface, and inter‑process communication—detailing their responsibilities, inter‑dependencies, and providing concrete code examples and diagrams.
This guide explains how to install, configure, and secure an NTP server on Linux, set restriction rules, add a local clock backup, configure logging, start the service, and then configure client machines to synchronize time reliably using ntpq and ntpdate commands.
When a Linux server shows performance problems, Netflix's performance team recommends using ten standard CLI tools within the first minute to capture key utilization, saturation, and error metrics, enabling rapid root‑cause identification before deeper analysis is needed.
Learn how to configure network interfaces on CentOS 7 using NetworkManager tools like nmcli, nmtui, and nm-connection-editor, rename devices, edit configuration files, and apply changes via systemctl, covering both command‑line and graphical methods for effective Linux network management.
This article explains the SSH protocol, its encryption mechanisms, authentication methods, key management, and practical commands for generating keys and configuring password‑less logins, providing a comprehensive guide for secure remote access.
This guide explains how to detect and mount USB storage devices on Linux, install NTFS support, view system logs, and set up swap space—either as a dedicated partition or a swap file—while covering swappiness tuning and enabling or disabling swap.
This article examines the conditions under which data may be lost when a Linux process crashes while writing a file, explaining page cache behavior, the roles of stdio versus system calls, dirty page handling, write‑back mechanisms, and strategies such as fflush, fsync, and direct I/O to ensure data integrity.
This guide explains how to classify storage devices, compare MBR and GPT partition tables, use Linux commands such as lsblk, fdisk, and gdisk to create partitions, format them with ext4 or XFS, and permanently mount them via /etc/fstab, providing a complete workflow for disk management.
This guide explains how to use the Linux utilities top and htop to monitor CPU, memory, disk I/O and network usage in real time, record performance data, analyze bottlenecks, and apply advanced techniques such as per‑process tracking, logging, chart generation and optimization recommendations.
This article provides two Bash scripts: one that continuously displays inbound and outbound traffic of a specified network interface, and another that remotely checks disk usage on up to 100 servers, issuing warnings when partitions exceed a defined threshold.
This guide explains Linux user and group concepts, classifications, UID/GID ranges, essential system files, and provides step‑by‑step commands for creating, modifying, and deleting users and groups, helping administrators securely manage system access.
This guide explains Linux's basic UGO permission model, the meaning of read/write/execute bits for files and directories, how to modify permissions with chmod, ownership with chown, group with chgrp, and extends control using ACLs, mask, and default settings.
This article provides a comprehensive overview of POSIX threads, covering their architecture, creation, synchronization, attributes, scheduling policies, advantages, drawbacks, and real‑world examples such as mutex protection, barrier synchronization, and a cross‑platform network server implementation.
This guide provides a comprehensive step‑by‑step checklist for hardening Red Hat Linux systems, covering shared account detection, redundant account lockout, root remote‑login restrictions, password complexity and lifespan policies, critical directory permissions, default umask settings, audit logging, remote log server configuration, history timestamping, SSH hardening, unnecessary service removal, Ctrl‑Alt‑Del disabling, and patch management.
Learn how to quickly set up and manage Ubuntu’s Uncomplicated Firewall (UFW) with step‑by‑step commands for enabling, disabling, resetting, configuring default policies, adding protocol, IP, and port rules, and deleting rules, empowering you to secure client machines efficiently.
This article explains why OAT's precheck fails due to mismatched ulimit values when SSH does not load PAM limits, and provides a step‑by‑step solution to enable PAM in sshd_config so the expected limits are applied correctly.
This article provides a comprehensive overview of Linux's task_struct, explaining how the kernel represents and manages processes and threads, detailing its internal fields, state handling, scheduling, credentials, memory layout, and special mechanisms such as hung‑task detection.
This article provides a collection of Bash scripts that let you retrieve detailed information about Linux processes by PID or name, query user account details, and apply a series of security‑hardening configurations to protect the system.
This article examines how the KPROBE_OVERRIDE feature, combined with eBPF, enables precise kernel‑level error injection, discusses its configuration requirements, demonstrates a practical example on a Mellanox NIC driver, and evaluates the associated security and performance implications.
This guide explains what file links are in Linux, distinguishes soft, hard, and symbolic links, and provides step‑by‑step command‑line examples for creating, inspecting, and removing each type of link, including handling directories and inode behavior.
The article covers Linux commands, shortcuts, file and directory management, permissions, users, searching, software repositories, manual pages, advanced topics like redirection, pipelines, processes, daemons, compression, compilation, networking, backup, and system control, providing practical examples and code snippets.
This comprehensive guide walks you through systematic JVM memory issue diagnosis, covering initial data collection, analysis of heap, metaspace, direct memory, stack problems, and practical command‑line tools, while offering actionable tips and real‑world examples for effective troubleshooting.
This tutorial walks through creating a software RAID 5 array on a CentOS 7 system using mdadm, covering partition preparation, array creation, filesystem formatting, mounting, configuration, monitoring, fault simulation, disk removal, re‑adding disks, and expanding the array to add a fourth member.
This article provides a comprehensive guide to the Linux su and sudo commands, explaining their differences, usage options such as login-shell and non-login-shell, how to switch users, set passwords, configure sudoers, and practical examples for managing user privileges securely.
This guide introduces five open‑source Linux command‑line utilities—nethogs, nload, cbm, iftop, and iPerf—detailing their purpose, usage examples, and key options for process‑level, interface‑level, host‑level monitoring, and network performance measurement.
This guide explains the concepts of Linux file systems, compares root and regular file systems, lists common embedded flash file systems, outlines required root‑FS directories, and provides a step‑by‑step procedure—including cross‑compilation, BusyBox configuration, mounting, and ramdisk creation—to build and test a minimal root filesystem for an embedded device.
This tutorial walks through installing HAProxy, configuring global, defaults, listen, frontend, and backend sections, setting up ACL‑based routing, defining server groups for default, website, and blog services, testing load‑balancing behavior, and accessing the HAProxy statistics page, all with complete command‑line examples.
This guide explains how to use the Linux /usr/bin/time utility to measure program execution time, memory usage, and other resources, covering its syntax, common options, custom format strings, and a comprehensive list of resource specifiers.
Linux founder Linus Torvalds confirmed that the kernel project has recently stripped more than ten maintainers linked to Russia, citing compliance requirements and U.S. sanctions, while the removed contributors' driver code remains in the source tree.
This guide walks through systematic techniques for locating passwords on a compromised Linux host—including searching file names, file contents, hidden directories, web configuration files, MySQL databases, backup folders, and encrypted archives—while demonstrating how to crack discovered hashes using Hashcat, John the Ripper, and LinPEAS.
This guide walks through the most frequent Linux system problems—boot failures caused by mis‑configured fstab, corrupted root partitions, missing kernel files, or hardware issues; network connectivity errors; MBR and GRUB bootloader faults; forgotten root passwords; and read‑only file‑system errors—providing step‑by‑step diagnostics, command‑line solutions, and recovery procedures.
With CentOS reaching end‑of‑life, this guide compares four stable, community‑backed Linux distributions—Rocky Linux, Ubuntu, Debian, and AlmaLinux—highlighting their origins, compatibility with RHEL, key features, and suitability as reliable replacements for production servers.
This article provides a comprehensive overview of how Linux kernel system calls are implemented on the x86-64 architecture, covering the conceptual differences from regular function calls, register conventions, initialization processes, syscall tables, and practical assembly examples such as write and getpid.
This guide explains how to use the Linux /usr/bin/time utility to measure program execution time, CPU usage, memory consumption, and other resources, covering its syntax, key options, custom format strings, resource specifiers, and the difference between the external command and the shell builtin.
When testing Linux server performance, you should monitor key metrics such as CPU usage, memory consumption, disk I/O, network bandwidth, process information, file system usage, system logs, boot and response times, context switches, and interrupts, using tools like top, vmstat, iostat, netstat, and custom Python scripts.
This article traces the evolution of Chinese operating systems from the early research era in the 1960s through the first and second waves of domestic Linux distributions, examines government policies and market dynamics, and discusses recent trends such as multi‑architecture support, root community building, and the ongoing debate over true国产 (indigenous) status.
This guide explains how to use the Linux df and du commands to check overall disk space, view partition types, inspect inode information, and determine the size of specific files or directories, with examples and options for human‑readable output.
This guide explains how LVM snapshots work, how to create them with copy‑on‑write, restore individual files or entire volumes, and merge snapshots back into the original logical volume, providing a practical backup solution without service interruption.
This article explains TCP connection states, the three-way handshake and four-way termination processes, provides essential Linux commands for monitoring connections, and offers practical tips for diagnosing network issues, handling SYN floods, TIME_WAIT problems, and implementing keepalive mechanisms to maintain reliable communication.
This comprehensive guide explores Linux file transfer fundamentals, covering local and remote methods, command‑line and GUI tools, protocols like SSH, FTP, and HTTP, security considerations, performance tuning, common issues, and practical best‑practice recommendations for reliable data movement.
This article introduces Linux interprocess communication (IPC), describes the characteristics and usage of unnamed and named pipes, message queues, shared memory, signals, and semaphores, and provides complete C code examples and a producer‑consumer demonstration that combine these mechanisms.
This guide explains how to use the Linux /usr/bin/time utility to measure program resource usage, covering its syntax, useful options, custom format strings, a full list of resource specifiers, and the difference between the external command and the shell builtin.
An in‑depth guide walks through the core concepts of Unix shell scripting, covering the purpose of a shell, prompt mechanics, echo usage, quoting rules, variable definition and export, exec versus source, grouping commands, parameter expansion, positional parameters, logical operators, I/O redirection, conditional statements, and loop constructs, all illustrated with clear examples.
This guide explains how to set up the free, open‑source Lynis tool on a CentOS 8 server, run comprehensive system audits, explore its command‑line options, and interpret the generated security reports to strengthen Linux host defenses.
This article walks through the anatomy of a Java Virtual Machine crash, explains how to read the generated hs_err_pid log and core dump, and provides practical debugging steps—including code examples, signal analysis, register context, and GDB commands—to pinpoint and resolve the root cause.
Learn how to leverage SSH for remote command execution, including running single and multiple commands, handling interactive sessions with pseudo‑terminal allocation, executing multi‑line commands, and running both local and remote scripts with parameter passing, all illustrated with practical examples.
This article provides concise answers to common DevOps interview questions, covering Linux boot processes, Kubernetes container execution, Git operations, Jenkins pipelines, DNS, networking, monitoring with Prometheus and Grafana, databases, SQL indexing, and collaboration and leadership scenarios.
This article explains Linux CPU cache architecture—from physical and logical cores, through L1/L2/L3 hierarchy and cache‑line basics, to write‑through/write‑back policies and coherence mechanisms—while demonstrating practical analysis with Valgrind and perf tools.
This article presents a comprehensive list of 17 in‑depth DevOps interview questions asked by a Swedish company, covering Linux boot processes, Kubernetes internals, Git workflows, Jenkins pipelines, networking, monitoring, databases, Docker, and soft‑skill topics to help candidates prepare effectively.
This article explains Linux swap fundamentals, detailing how the kernel uses swap partitions or files, the role of the swappiness parameter in balancing cache reclamation versus anonymous page swapping, the operation of kswapd, and the impact of memory watermarks on reclamation decisions.
This article explains the Linux inode structure, how common commands like cp, rm, and mv interact with inodes, the differences between hard and soft links, and provides a detailed overview of system and user log files, log levels, and configuring a centralized rsyslog server.
The article explains how Linux manages memory page watermarks, when the allocator falls back to kswapd, and the exact conditions that trigger direct compaction via __alloc_pages_direct_compact, then walks through the core compaction functions—try_to_compact_pages, compact_zone_order, compact_zone, and the page‑migration helpers—illustrated with flow diagrams and real kernel code.
This article explains the design, principles, and C implementations of Linux kernel synchronization primitives—including spinlocks, semaphores, read‑write locks, and mutexes—illustrated with real‑world analogies, code snippets, and usage constraints in interrupt and multi‑CPU contexts.
This article provides a thorough introduction to the GNU Debugger (GDB), covering its core capabilities, startup methods, compilation requirements, a wide range of debugging techniques—including breakpoints, memory inspection, disassembly, reverse execution—and detailed guidance for multithreaded debugging on Linux systems.
This article explains the Linux Virtual Server (LVS) load‑balancing architecture, defines key terms such as VS, RS, VIP, DIP, and CIP, and details the four operating modes—NAT, DR, TUN, and FULLNAT—including their workflows, configuration steps, and practical considerations.
At the recent virtual eBPF summit, Isovalent CTO Thomas Graf revealed that Microsoft is developing a Windows version of eBPF, aiming for cross‑platform compatibility with Linux, while the IETF works on standardizing the eBPF ISA and verifier to ensure secure, portable kernel bytecode execution.
This guide walks through downloading the Nginx source package, extracting it, compiling and installing it to a custom directory, configuring a systemd service unit, and finally starting and verifying the server on a Linux system.
This guide explains what a program and a process are, describes process creation, lifecycle, and identifiers, and provides detailed usage of essential Linux commands such as ps, top, pgrep, pstree, lsof, vmstat, iostat, iftop, dstat, as well as foreground/background control and scheduling with at and crontab.
Although many still use Python 3.8, its support ends in October 2024, after which no error or security fixes will be released, so developers should plan timely upgrades to newer Python versions, considering package compatibility, Linux distribution support, and the ongoing need for regular version updates.
This guide explains the core concepts of Linux namespaces and Cgroups, shows how Kubernetes pod specifications use CPU requests and limits, and provides step‑by‑step commands and parameter details for configuring Cgroup settings to restrict container CPU consumption.
This guide explains what the check-docker-connection tool does, its required environment, command‑line options, how to run it inside a Docker container, and provides step‑by‑step examples for monitoring single or multiple containers and displaying the top N containers by connection count.
This guide clarifies the differences between the Linux commands su and sudo, explains their options and effects on the shell environment, shows how to create and manage users, edit the sudoers file, and choose the appropriate method for secure privilege escalation.
This tutorial explains how to use Linux Logical Volume Management (LVM) to create physical volumes, volume groups, and logical volumes, covering essential commands, formatting, mounting, and expanding storage without data loss, all illustrated with clear examples and screenshots.
This article introduces CGDB, explains how to choose the appropriate GDB version, provides step‑by‑step installation commands for both CGDB and GDB, and demonstrates practical debugging scenarios with MySQL, including attaching to processes, inspecting threads, analyzing core dumps, and adjusting runtime variables.
This article provides a detailed, practical guide for increasing Redis memory on Linux by adjusting Redis configuration, expanding system swap space, tuning kernel overcommit settings, and monitoring usage with command‑line tools.
This tutorial explains Linux LVM fundamentals, walks through creating and removing physical volumes, building volume groups, managing logical volumes—including formatting, mounting, extending, shrinking—and demonstrates how to take and restore snapshots using concrete command‑line examples.
Google is integrating a Linux‑compatible terminal into Android via the Android Virtualization Framework, allowing users to launch a Debian‑based VM directly from developer options and run Linux software on their phones without third‑party tools.
This guide explains how to use Linux's crontab command to create scheduled tasks, covering its features, common use cases, syntax details, example schedules, editing procedures, output redirection, and necessary script permissions for reliable automation.
This guide introduces five essential Linux command‑line utilities—nethogs, nload, cbm, iftop, and iPerf—explaining their focus areas, key features, and example commands for monitoring process‑level bandwidth, interface traffic, host connections, and conducting network performance tests across multiple machines.
This article walks operations engineers through the concepts, components, and detailed installation steps for setting up a Zabbix distributed monitoring system on Linux, including server and agent configuration, web front‑end deployment, custom items, triggers, and email alerts.
This guide shows how to install PHP (8.0‑8.3) and Composer in a single step on Linux or macOS, explains the features of the static binaries, provides verification commands, and details manual installation for Windows with a full list of supported extensions.
This comprehensive guide walks you through SFTP server planning, SSH configuration, account creation, directory permissions, logging, monitoring, high‑availability setups, and automation scripts, providing step‑by‑step commands and best practices for secure and scalable file transfers.
Learn 25 practical Linux performance tuning techniques—from adjusting kernel parameters like swappiness and ulimit to optimizing I/O schedulers, network buffers, and enabling HugePages—each with clear commands and step‑by‑step instructions to help you maximize system responsiveness and throughput.
This guide introduces Vim's built‑in help, explains its multiple editing modes, and provides step‑by‑step commands for opening files, inserting text, navigating, deleting, searching, replacing, copying, exiting, and handling swap‑file protection on Linux systems.
In September 2024, TencentOS sent two kernel engineers to Vienna to attend the Linux Plumbers Conference and the Linux Kernel Developers' Netconf, where they presented cutting‑edge research on network diagnostics, SWAP allocation, and memory management, fostering collaboration with leading open‑source contributors.
This article walks through the Linux kernel mechanisms for creating and destroying processes, covering copy‑on‑write, the fork/vfork/clone system calls, the kernel_clone implementation in kernels 5.0 and 6.5, the copy_process workflow, and the steps the kernel takes to wake up a new task and clean up a terminated one.
This tutorial explains how to use the Linux fmt command to reformat text, customize line width, highlight the first line, split long lines, and control spacing, providing clear examples and command options for efficient text processing.
This article presents an extensive collection of Linux interview questions that span core concepts such as kernel fundamentals, memory management, process handling, interrupt mechanisms, filesystem structures, device driver development, and system performance tuning, providing a thorough preparation resource for candidates.
Learn how to monitor Linux processes using four powerful tools—ps, dstat, top, and htop—by exploring their options, output fields, and practical usage examples, with clear explanations of command syntax, common flags, and interpreting system resource statistics.
The article explains why WeChat lacks an official Linux client, describes native versions available for certain Chinese Linux distributions such as Deepin, UOS, and OpenKylin, and provides instructions for installing the app via those stores or using Wine to run the Windows version on other Linux distributions.
This guide provides step‑by‑step instructions for installing the Allure test reporting tool on Windows, macOS, and Linux, covering Java setup, environment variables, verification commands, important considerations, and how to generate and view test reports.
retsnoop is an eBPF‑based tracing utility that uses wildcard patterns to hook kernel functions, automatically captures full stack traces whenever a function returns an error, and offers three complementary modes—stack trace, function‑call trace, and LBR—to quickly pinpoint the source of kernel failures, with practical examples and source‑code insights.
This guide explains the concepts of hard, soft, and symbolic links in Unix/Linux, showing step‑by‑step commands to create, inspect, and remove links, compare inode numbers, and understand their behavior and limitations.
The article explains how the Linux free utility calculates the “buffers” and “cached” fields, detailing their definitions, the kernel source functions that produce them, the role of block‑device page cache versus ordinary file cache, and how to verify the numbers with simple commands.
This guide walks you through installing Squid on Linux, configuring caching, ACLs, and network settings, troubleshooting startup issues, and testing the proxy to improve bandwidth usage and enforce access control for your internal users.
