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.
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.
