This guide explains how to use the Linux /usr/bin/time command to measure program execution time, memory usage, and other resource metrics, covering syntax, options, custom output formats, and the differences between the built‑in shell time and the external utility.
This article explains TCP’s three‑way handshake, details each socket state from CLOSED to ESTABLISHED, describes SYN‑Flood attacks, and provides Linux kernel tuning commands to optimize TCP performance and security.
Rhino Linux is an Ubuntu‑based rolling‑release distribution that combines the Pacstall package manager for unified handling of Deb, Pacstall and Flatpak packages with a heavily customized Xfce desktop, offering a polished desktop experience, built‑in utilities, and support for various hardware platforms.
This tutorial explains how to use the Linux fmt utility to reformat text, covering basic syntax, line‑width adjustments, first‑line indentation, line splitting, and spacing options with clear examples and command‑line snippets tested on Ubuntu 24.04.
This guide details practical steps for securing Linux accounts, including disabling unnecessary super‑user accounts, enforcing strong password policies, locking critical files, restricting privileged commands, tightening file permissions, and configuring network and system settings to prevent spoofing, DoS, and SYN attacks.
This guide explains how to use the Linux lsof command to list information about open files, processes, directories, sockets, and network connections, covering basic usage, column meanings, filtering options, repeated mode, and practical examples for system administration tasks.
This guide explains why MySQL or Java processes can consume 700‑900% CPU in production, walks through step‑by‑step diagnosis using Linux tools, and provides concrete remediation techniques such as indexing, caching, thread analysis, and code adjustments to restore normal performance.
Learn step‑by‑step how to capture a Linux core dump with kdump, install the crash utility and debuginfo packages, and use commands like sys, bt, ps, files, and sym to trace the root cause of kernel panics, illustrated with a real‑world case study.
This guide outlines the ten core tool categories—from Linux basics and networking services to scripting, firewalls, monitoring, clustering, and backup—that a Linux operations engineer should master to become an effective sysadmin.
This article explains Docker's OverlayFS/Overlay2 storage driver, detailing its layered image architecture, union‑mount mechanics, read/write behavior, metadata organization, and the roles of image, layer, and init layers within the container filesystem.
This guide explains the concept of Linux network bridges, how they operate at the data‑link layer, and provides step‑by‑step instructions for creating, configuring, and managing bridges using brctl, nmcli, and ip commands across various distributions, including details on STP activation and IP address setup.
This guide explains the concept of reverse SSH, why it is needed to access servers behind restrictive firewalls, and provides step‑by‑step commands and configuration tips—including port forwarding with the -R option and recommended sshd settings—to establish a reliable reverse tunnel.
This article explains why Chinese desktop operating systems struggle with software availability, compares virtual machines with Wine, and details how Wine’s compatibility layer leverages portable CPU instructions and system‑call interception to run Windows programs on Linux efficiently.
This guide explains how to install fio, run various disk performance tests—including random and sequential reads/writes and mixed workloads—while avoiding data loss, and shows how to interpret key metrics such as IOPS, bandwidth, and latency.
The article outlines the key competencies a DevOps engineer must master—including programming, Linux system knowledge, configuration management, infrastructure-as-code, CI/CD tools, networking and security, monitoring, and cloud services—to guide readers on building a comprehensive skill set for effective DevOps practice.
Learn how to harness the power of the xargs command with ten detailed examples covering basic usage, custom delimiters, output limits, interactive prompts, safety options, and advanced integrations with find, grep, and file handling, all illustrated with clear command-line demonstrations.
This guide explains how to use the Linux cut command for extracting specific characters, fields, and ranges from text files, covering options like -c, -f, -d, complement, custom output delimiters, and combining cut with other Unix utilities for powerful text processing.
This guide walks you through installing Erlang, downloading and building RabbitMQ 3.0.4 from source on a Linux system, verifying the installations, starting the server in detached mode, checking its status, and troubleshooting common port‑conflict issues on CentOS 6.
This guide walks through the Linux mount and umount commands, covering everything from mounting CD‑ROMs and floppy disks to binding mount points, using /etc/fstab, listing specific filesystem types, and handling forced or lazy unmounts with clear, step‑by‑step examples.
This guide walks through a comprehensive Linux hardening process on RHEL7, covering account lockdown, password policies, SSH port changes, SELinux activation, firewall minimization, file attribute protection, and compiler restrictions, all illustrated with concrete commands and configuration examples.
The article explains why, despite the low cost and fast development cycle of MCU‑RTOS combos, certain demanding applications—such as high‑resolution displays, complex GUIs, intensive networking, large storage, AI or image processing—benefit from switching to an embedded Linux platform, illustrated with a real STM32 project case.
This guide walks you through updating Ubuntu 24.04, adding Docker's repository, installing the Docker engine, starting and enabling the service, verifying the installation, adding your user to the Docker group, and running basic Docker commands, all with exact terminal commands.
This guide walks through verifying MySQL 8.0.16+, copying and editing the mysqld.service file, setting the Service Type to notify, adding NotifyAccess, adjusting ExecStart, reloading systemd, restarting MySQL, and checking its status, while covering SELinux, firewall, and notification‑delay optimizations.
This guide explains how systemd’s multi‑instance (template) services work, shows how to configure and manage them with concrete examples such as OpenVPN client instances, and highlights their core features, practical steps, logging, typical scenarios, and advantages for Linux administrators.
This article explains Linux redirection, the three standard data streams (stdin, stdout, stderr), file descriptors, how to adjust their limits, common redirection syntax, and the concepts, types, and usage of both anonymous and named pipes for inter‑process communication.
Learn to quickly diagnose the “Address already in use” error on Linux by listing listening ports with netstat, ss, and lsof, interpreting their output, filtering results, and freeing conflicted ports, with example commands and explanations of each option.
This guide walks you through installing Erlang, downloading and extracting RabbitMQ 3.0.4, starting the server in detached mode, verifying its status, and troubleshooting common port‑conflict errors on CentOS 6, with complete command‑line examples.
Learn how Linux Virtual Server (LVS) works, covering core concepts such as VS, RS, VIP, DIP, and CIP, and explore its four operating modes—NAT, Direct Routing, TUN, and FULLNAT—along with detailed workflow diagrams, configuration tips, and practical considerations for deployment.
This article introduces the core Linux kernel data structures involved in process management and scheduling—task_struct, sched_entity, rq, and sched_avg—explaining their key fields, relationships, and how they enable the kernel to track process state, timing, memory, and load‑balancing decisions.
This guide presents a comprehensive overview of the most frequently used Linux shell utilities for text processing—including find, grep, xargs, sort, uniq, tr, cut, paste, wc, sed, and awk—providing clear examples, common options, and practical tips for effective command‑line scripting.
When a Linux server shows performance issues, the first minute is critical; this guide walks you through ten standard command‑line tools—uptime, dmesg, vmstat, mpstat, pidstat, iostat, free, sar, and top—explaining what each metric means and how to interpret the output for quick troubleshooting.
This tutorial walks you through installing BIND on Linux, configuring forward and reverse DNS zones, customizing ports, logging, access control, master‑slave replication, testing with dig/host, and handling AppArmor restrictions, providing complete commands and configuration examples.
This guide explains why MySQL and Java processes can exceed 900% CPU usage in production, and provides step‑by‑step methods—using top, show processlist, jstack, index tuning, caching, and code adjustments—to diagnose, mitigate, and prevent such spikes.
This article traces the evolution from real‑mode segmentation to modern paging, explains segment and page‑table structures on x86 and ARM, dissects kernel macros such as PGDIR_SHIFT and PUD_SHIFT, and demonstrates a kernel module that translates a process's virtual address to its physical address.
This guide walks through typical Linux operational problems—including boot failures caused by fstab errors, root‑filesystem corruption, missing kernel files, MBR or GRUB issues, network hardware and configuration faults, DNS mis‑settings, service port problems, forgotten root passwords, and read‑only file‑system errors—providing step‑by‑step troubleshooting methods and command‑line fixes.
This comprehensive guide explains Linux's netfilter firewall framework, its five hook points, how iptables maps rules to tables and chains, and provides step‑by‑step examples for traffic filtering, NAT, custom chains, and rule persistence using iptables commands.
Learn step‑by‑step how to install, configure, and secure an NTP server on Linux, restrict client access, add a local clock fallback, set logging and drift parameters, then configure Linux clients to synchronize time, start services, and verify synchronization status.
This step‑by‑step guide explains how to safely disable a Linux user account by opening a terminal, checking the account status, locking the login with usermod, verifying the lock, and optionally re‑enabling the account, all using simple command‑line instructions.
This guide explains Linux network management, covering IP address and routing configuration, interface naming rules, GRUB tweaks for CentOS and Ubuntu, file‑based setups for CentOS 7, Ubuntu 16.04, Ubuntu 18.04+ with netplan, and graphical configuration via NetworkManager, plus service differences.
The article explains how to ensure data correctness in Linux inter‑process shared memory communication by using synchronization mechanisms—semaphores, mutexes, and condition variables—providing step‑by‑step code examples for each method and discussing their proper initialization, usage, and potential pitfalls.
Learn how to secure a Linux server by configuring firewalls with iptables and firewalld, managing user permissions, setting up auditd, applying automatic updates, and deploying intrusion detection tools like OSSEC and AIDE, plus a step‑by‑step response workflow for real‑world attack scenarios.
This article provides a comprehensive, step‑by‑step guide to tuning Kunpeng‑based servers, covering hardware characteristics, matrix‑multiplication benchmarks, NUMA‑aware scheduling, compiler and JDK optimizations, acceleration libraries, disk and NIC tuning, and a practical MariaDB performance‑tuning workflow.
This step‑by‑step tutorial shows how to install Percona XtraBackup 2.4, create full, incremental and compressed backups of MySQL 5.1‑5.7, prepare the backups, and restore data using Docker or native Linux packages.
At the Open Source Summit Europe, Linus Torvalds warned that the Linux kernel’s aging maintainers and a shrinking pool of interested developers threaten succession, stressing that future leaders must earn community trust through sustained contributions, while better mentorship, documentation, and outreach are needed to attract new talent.
This tutorial explains how to use the gzexe utility to encrypt a shell script, covering script preparation, making it executable, running gzexe to produce a compressed encrypted file, verifying and executing the encrypted script, optional decryption, and notes on security limitations and installation.
This article explains the Linux kernel limits that determine how many files and TCP connections a server can open, shows how to tune fs.file-max, soft/hard nofile, and fs.nr_open, estimates realistic connection counts based on memory, and provides practical configuration examples for large‑scale services.
This guide shows how to edit the MySQL server startup script to add skip-grant and skip-networking options, restart the MySQL service, change the root user password, and then revert the script changes, providing step‑by‑step commands and screenshots for each operation.
This article explains why Linux kernel network packet loss occurs, covering causes such as UDP checksum errors, firewall misconfigurations, rp_filter settings, buffer overflows, and hardware faults, and provides detailed diagnostic steps and practical solutions to identify and resolve each issue in Linux environments.
This article explains the Linux zombie process concept, shows how they are created when a parent neglects wait(), demonstrates the issue with sample C code and ps output, discusses the risks of PID exhaustion, and provides proper handling techniques using wait() and process reaping.
This guide walks through essential Linux system fundamentals, covering time management, hostname and OS details, user and group configuration, core networking tools, disk usage commands, and real‑time process and memory monitoring, providing practical examples and command syntax for each topic.
This guide walks you through installing common backend services on CentOS—building Redis from source, deploying RabbitMQ via RPM, and adding Nginx with YUM—while explaining key concepts like tarballs, RPM metadata, and YUM repository configuration.
This guide shows how to install the nslookup tool on Debian/Ubuntu and CentOS/RHEL systems and provides seven practical usage examples, including querying IP addresses, specifying DNS servers, retrieving specific record types, performing reverse lookups, setting search domains, using the set command, and exiting the interactive mode.
This article explains how to use eBPF fentry and fexit probes to monitor the Linux unlink system call, compares them with kprobes, provides complete C and Go examples, shows compilation with eunomia‑bpf, and discusses the low‑overhead advantages of fentry for kernel tracing.
After installing multiple LNMP services, a reboot left the Ubuntu system unable to run apt update due to a read‑only filesystem caused by a missing /etc/fstab, and this guide walks through diagnosing the issue, restoring fstab with correct UUIDs, remounting the root, and backing up the configuration.
This article explains how to use Linux eBPF kprobe (and kretprobe) to dynamically instrument the unlink system call, covering the underlying concepts, required kernel headers, full eBPF source code, compilation with both eunomia‑bpf and cilium/ebpf, and a detailed comparison with tracepoint probes.
This tutorial walks you through safely upgrading OpenSSH (to 8.3p1) and OpenSSL (to 1.1.1g) on CentOS 7, covering prerequisite OpenSSL upgrade, service shutdown, dependency installation, source compilation, configuration tweaks, and verification steps.
This article explains Linux's page reclamation mechanisms, covering the LRU list algorithm, the second‑chance method with PG_active and PG_referenced flags, and the direct reclaim path triggered by alloc_page, including the role of kswapd, waiting queues, and key kernel functions such as lru_cache_add, mark_page_accessed, try_to_free_pages, and throttle_direct_reclaim.
This article provides a thorough overview of Linux kernel debugging techniques, covering pseudo‑filesystems such as procfs, sysfs, debugfs and relayfs, as well as essential tools like printk, ftrace, trace‑cmd, kprobe, systemtap, kgdb, kgtp, perf, and other modern tracers, helping developers diagnose and optimise kernel behavior.
This guide uses a four‑detective metaphor to teach Linux process monitoring tools—ps, dstat, top, and htop—covering their options, output fields, interactive commands, and practical examples for effective system performance analysis.
This guide explains how to monitor memory usage on Linux servers, identify common causes of sudden memory consumption such as leaks, stuck processes, or high load, and provides concrete commands and remediation steps to stabilize system performance.
This guide walks through practical Linux command-line techniques—including generating file checksums, locating files quickly, editing long commands, inspecting and managing processes, capturing terminal output, examining binary dependencies, and using various text‑viewing utilities—to boost everyday system administration efficiency.
This article presents a curated list of twenty practical Linux command‑line tricks—from tab completion and directory navigation to command chaining, history search, log monitoring, and useful shortcuts—that help both beginners and seasoned users work faster and avoid common pitfalls.
This article introduces eBPF fundamentals, explains the Compile‑Once‑Run‑Everywhere (CO‑RE) approach, compares it with traditional eBPF, outlines best practices, and walks through a complete Go‑based example using the Cilium/eBPF library and the eunomia‑bpf runtime.
This guide explains cURL’s command‑line syntax, common options, error codes, and demonstrates how to build a C program that monitors a log file, creates timestamped backups, and automatically uploads them to an FTP server using cURL.
This guide explains the concept of Linux loop devices, shows how to create and mount a file as a virtual block device using both the simple mount -o loop method and the explicit losetup approach, and dives into the kernel implementation and typical use cases.
This guide walks through the purpose, advantages, required Linux packages, Go libraries, exact installation commands, and version details needed to set up a functional eBPF development environment on an Ubuntu system, while explaining each step’s rationale.
This guide introduces two open‑source shell scripts—CentOS_Check_Script and CentOS_Protective_Script—designed to enforce security hardening on Red Hat/CentOS systems, covering password policies, audit log protection, user management, and various security controls, with usage instructions and download links.
This guide walks through the step‑by‑step process of downloading, compiling, and enabling the MongoDB extension for PHP on a Linux server, covering both online and offline installation methods and how to verify the extension is loaded successfully.
An in‑depth post‑mortem of a recurring midnight kernel panic caused by a malformed sk_buff structure, detailing how vmcore analysis, packet inspection, and netfilter hook tracing pinpointed a third‑party module bug in Linux 5.10, and outlining remediation steps.
When a data platform server suddenly shows CPU utilization near 99% despite modest traffic, this guide walks through pinpointing the offending Java process, tracing the high‑load thread, uncovering a time‑conversion routine that over‑calculates seconds, and applying a lightweight fix that drops CPU load by dozens of times.
This guide walks through creating partitions, mounting devices and filesystems using the Linux mount command, exploring common scenarios such as mounting CD-ROMs, viewing current mounts, binding directories, remounting, mounting ISO images, and safely unmounting with options like lazy, force, and selective unmounting.
This article compiles ten practical operations‑engineer guidelines—ranging from change rollbacks and safe command aliases to backup verification, monitoring, and cautious automated failover—to help maintain high availability and avoid costly production incidents.
This article walks through creating a first eBPF program using C and Go on Ubuntu 22.04, covering required dependencies, kernel‑space vs user‑space concepts, event selection, BPF map definition, and a tracepoint function that measures per‑process CPU time.
This article explains the Linux kernel device driver model introduced in 2.6, how devices, buses, classes and drivers are represented, how the sysfs virtual filesystem exposes their hierarchy, and walks through the registration and matching process for platform buses, drivers, and devices with detailed code examples.
This guide explains how to prepare source and target servers, install iPerf, run it in server and client modes on Windows (or Linux), and use specific commands to measure TCP bandwidth, UDP jitter, packet loss, and network latency, including required firewall and security‑group settings.
Learn how to accelerate Docker image pulls by configuring registry mirrors, then follow step‑by‑step instructions to pull, run, inspect, and manage Nginx containers, including commands for starting, stopping, logging, networking, and modifying container files, ensuring efficient container operations.
This comprehensive guide walks IT and DevOps professionals through understanding ARM and x86 architectures, setting up the build environment, creating and customizing base images, optimizing size and performance, and packaging for distribution, with practical commands and best‑practice recommendations.
This guide walks through comprehensive Linux security hardening on RHEL7, covering account lockout, password policies, SELinux configuration, SSH port changes, root login disabling, umask restriction, immutable system files, GCC limitation, log protection, minimal firewall rules, and related command examples.
The article explains how Linux separates board‑level information from drivers using a bus‑device‑driver model, illustrating high cohesion and low coupling with concrete code examples, matching mechanisms, and the evolution toward device trees for scalable hardware abstraction.
This guide explains Linux's traditional permission model, introduces Access Control Lists (ACL) and the crucial mask concept, shows how to view and modify ACLs with getfacl/setfacl, and provides practical examples for correctly configuring file permissions.
This comprehensive guide explains DNS fundamentals, Linux client configuration, BIND9 server setup, advanced features like DNSSEC and DoH, and essential troubleshooting and security practices, empowering system administrators and network engineers to manage and secure DNS services effectively.
This guide introduces tcpdump, a powerful command‑line packet analyzer, covering its history, core features, basic usage, advanced filtering techniques, practical tips, and real‑world scenarios to help system administrators and network engineers diagnose and monitor network issues effectively.
This article walks through a production‑level OceanBase connection‑timeout incident, detailing how to examine OBProxy logs, capture and analyze network packets with tcpdump and Wireshark, identify a blocked random port, and apply kernel‑parameter fixes to prevent the issue.
Learn how to enable and configure IPv6 on Ubuntu, covering its benefits, checking interface support, editing Netplan or legacy network files, setting static addresses, applying changes, and verifying the configuration with practical command examples.
Celebrating Linux’s 33rd birthday, this article traces its humble 1991 beginnings as Linus Torvalds’s “small hobby” to its ubiquitous presence today across desktops, servers, mobile devices, supercomputers, and even the International Space Station, highlighting its profound impact on modern computing.
This guide explains how to use the dd command to clone an Ubuntu system disk to another drive or an image file, covering prerequisites, preparation steps, backup and restore commands, optional compression, advantages, drawbacks, use cases, and important precautions.
This article traces the origins and evolution of CentOS, explains the shift to CentOS Stream, outlines the end‑of‑life schedule for CentOS Linux 7 and 8, and evaluates a range of alternative Linux distributions and domestic operating systems for enterprises seeking a replacement.
This article explains what swap space is, why it matters for system stability and performance, and provides detailed Linux commands and procedures for creating, configuring, activating, and monitoring swap files or partitions.
Zero‑copy techniques such as mmap + write, sendfile, and sendfile + DMA scatter/gather reduce CPU‑memory copies and context switches compared with traditional read/write IO, improving performance for high‑throughput systems like RocketMQ and Kafka, while explaining user‑kernel mode, DMA, and their trade‑offs.
This guide presents twenty practical Linux command‑line shortcuts—including tab completion, directory navigation, command chaining, history search, log monitoring, and alias creation—that help both beginners and experienced users work faster and avoid common pitfalls.
WebVM is an open‑source project that lets you launch a complete Linux virtual machine inside a web browser, supporting multiple programming languages and enabling deployment via GitHub Pages without any local installation.
This comprehensive guide explains why Linux system monitoring is crucial, outlines key metrics such as CPU, memory, disk I/O, network, and process usage, recommends essential command‑line tools, and provides advanced techniques, automation scripts, best practices, and common pitfalls to ensure reliable, secure server performance.
Learn the differences between Source NAT (SNAT) and Destination NAT (DNAT), their definitions, mechanisms, key use cases such as address sharing, load balancing, and security, and follow step‑by‑step iptables examples to configure these NAT rules in a typical network scenario.
This tutorial explains Linux Logical Volume Manager (LVM) fundamentals, walks through creating and removing physical volumes, building and deleting volume groups, provisioning logical volumes, formatting and mounting them, and performing size extensions, reductions, and snapshot operations with concrete command examples.
This guide explains how to configure additional routing rules for a second network interface on Linux by creating a new policy routing table, adding specific routes and rules with iproute2 commands, and verifying that traffic uses the intended NIC.
This guide explains practical commands like du, find, and lsof to locate large directories or deleted files consuming disk space, and shows how to adjust reserved filesystem space with tune2fs to reclaim lost capacity.
This guide explains the purpose of common Linux log files, how syslog and klogd collect system and kernel messages, the structure of syslog entries, configuration of /etc/rsyslog.conf for both receiving and forwarding logs, and how to manage log rotation with logrotate.
Learn how to use Linux process-monitoring tools—ps, dstat, top, and htop—by mapping each command to a character from the classic “Four Great Detectives,” while covering essential options, output fields, and practical tips for effective system observation.
This guide provides a concise reference of essential Linux commands for file handling, process control, networking, system information, and package management, helping users quickly perform common administrative tasks from the command line.
This guide explains how to use the Linux /usr/bin/time utility to analyze program performance—including user and kernel CPU time, memory usage, and other resources—by invoking the command with various options, customizing output formats, redirecting results, and distinguishing it from the shell built‑in time command.
