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This article provides an in-depth exploration of methods to inspect all open sockets in the Linux operating system, with a focus on the /proc filesystem and the lsof command. It begins by addressing the problem of sockets not closing properly due to program anomalies, then delves into how the tcp, udp, and raw files under /proc/net offer detailed socket information, demonstrated through cat command examples. The lsof command is highlighted for its ability to list all open files and sockets, including process details. Additionally, the ss and netstat tools are briefly covered as supplementary approaches. Through step-by-step code examples and thorough explanations, this guide equips developers and system administrators with robust socket monitoring techniques to quickly identify and resolve issues in abnormal scenarios.

This paper thoroughly examines the default output format of the ls command in Linux systems, analyzing why filenames are displayed in a single line separated by spaces. By detailing the working mechanism of the -1 option in the ls command and combining pipeline commands with terminal output characteristics, it provides multiple solutions for achieving one filename per line. The article includes complete code examples and underlying mechanism analysis to help readers fully understand the technical details of Linux file listing output.

This paper provides an in-depth exploration of methodologies for debugging remote server port access issues in Linux systems. By analyzing core principles of network connectivity, it details the use of traceroute, nmap, netstat, and other tools for diagnosing firewall blocks, binding address configurations, and routing problems. The article offers comprehensive troubleshooting workflows and practical command examples to help system administrators quickly identify and resolve network connection obstacles.

This paper comprehensively explores methods for creating virtual serial ports in Linux systems, with focus on pseudo-terminal (PTY) technology. Through socat tool and manual PTY configuration, multiple virtual serial ports can be emulated on a single physical device, meeting application testing requirements. The article includes complete configuration steps, code examples, and practical application scenarios, providing practical solutions for embedded development and serial communication testing.

This paper provides an in-depth analysis of various methods for monitoring peak memory usage of processes in Linux systems, focusing on the /proc filesystem mechanism and GNU time tool capabilities. Through detailed code examples and system call analysis, it explains how to accurately capture maximum memory consumption during process execution and compares the applicability and performance characteristics of different monitoring approaches.

This technical article provides a detailed explanation of how to view command history with date and time stamps in Linux systems. By configuring the HISTTIMEFORMAT environment variable, users can permanently set the time display format for bash history records. The article covers temporary settings, permanent configuration, various time format options, and alternative solutions for zsh shell, complete with code examples and configuration steps.

This technical paper provides an in-depth exploration of methods for joining multiple file names into a single line with custom delimiters in Linux environments. Through detailed analysis of paste and tr commands, the paper compares their advantages and limitations, including trailing delimiter handling, command simplicity, and system compatibility. Complete code examples and performance analysis help readers select optimal solutions based on specific requirements.

This article provides a comprehensive analysis of 'Permission denied' and 'command not found' errors when executing scripts with sudo in Linux systems. By examining file permission mechanisms and PATH environment variable differences, it explains the root causes and solutions, including chmod permission settings, PATH environment variable workings, and environmental isolation during sudo execution. The article combines practical cases to offer complete troubleshooting procedures and effective repair methods.

This article provides an in-depth exploration of techniques for controlling USB device power states through the terminal in Linux systems. Based on Linux kernel documentation and practical application experience, it details the mechanisms for direct USB power management via the sysfs filesystem, including core functionalities such as power level settings and autosuspend configurations. The article contrasts implementation differences across various kernel versions and presents alternative solutions like the PowerTOP tool. Through specific code examples and operational steps, it assists users in understanding how to effectively manage USB device power states for practical scenarios such as remote control of USB fans and other peripherals.

This technical paper provides an in-depth analysis of permission denial issues when using sudo commands with output redirection in Linux systems. By examining shell execution mechanisms and sudo privilege models, it explains the root causes of permission errors and presents four effective solutions: using sudo sh -c for compound commands, creating executable scripts, launching interactive sudo shells, and employing tee command for output handling. Each method includes detailed code examples and scenario analysis to help developers comprehensively resolve privilege redirection challenges.

This technical article explores methods to retrieve network interface throughput statistics on Linux and UNIX systems, focusing on parsing ifconfig output as a standard approach. It includes rewritten code examples, comparisons with tools like sar and iftop, and analysis of their applicability for real-time and historical monitoring.

This article provides an in-depth exploration of various methods for permanently setting environment variables in Linux systems, focusing on user-level configuration files (such as .bashrc and .profile) and system-level configuration files (like /etc/environment). Through specific code examples and configuration steps, it explains how to ensure environment variables persist across terminal sessions and discusses the activation mechanisms and applicable scenarios of different methods. The article also includes the implementation of an automation script to simplify the configuration process, while emphasizing configuration security and best practices.

This article provides an in-depth analysis of common parameter order errors when combining find and cp commands in Linux systems. Through concrete examples, it demonstrates the proper usage of the -exec parameter in find commands, explains the mechanism of the {} placeholder, and offers complete command-line solutions. The paper also explores various search options of the find command and safe usage techniques for cp commands to help readers avoid common file operation mistakes.

This article provides an in-depth exploration of the sysctl configuration method for allowing non-root processes to bind to privileged ports (1-1024) on Linux systems. By analyzing the mechanism of the net.ipv4.ip_unprivileged_port_start parameter, it details how to lower the port permission threshold and implement security hardening with iptables. The paper compares the sysctl approach with traditional solutions like capabilities, authbind, and port forwarding, offering complete configuration examples and security recommendations to help developers simplify development environment setup while maintaining system security.

This article provides an in-depth exploration of memory usage monitoring in Linux systems. It begins by explaining key metrics in the top command such as VIRT, RES, and SHR, revealing limitations of traditional monitoring tools. The advanced memory calculation algorithms of smem tool are detailed, including proportional sharing mechanisms. Through comparative case studies, the article demonstrates how to accurately identify true memory-consuming processes and helps system administrators pinpoint memory bottlenecks effectively. Memory monitoring challenges in virtualized environments are also addressed with comprehensive optimization recommendations.

This technical paper comprehensively examines multiple approaches to automatically create destination directories when copying files in Linux systems. Based on high-scoring Stack Overflow answers and practical scenarios, it systematically analyzes the combination of mkdir -p and cp commands, GNU cp's --parents option, and the usage of $_ special parameter. Through detailed code examples and principle analysis, it elaborates on applicable scenarios, compatibility considerations, and best practices for system administrators and developers.

This paper provides an in-depth examination of nohup process management techniques in Linux systems, focusing on process identification, termination methods, and automated scripting solutions. The article thoroughly explains the working mechanism of nohup command, presents multiple approaches for obtaining process IDs including ps command with grep filtering and utilizing $! variable for PID preservation. It distinguishes between standard kill commands and forceful termination using kill -9, supported by practical code examples demonstrating automated process management workflows. Additionally, the paper discusses output redirection, log file monitoring, and other practical techniques, offering system administrators and developers a complete solution set for nohup process management.

This article provides an in-depth exploration of excluding specific directories during file copy operations in Linux systems. Since the standard cp command lacks native exclusion functionality, we focus on the powerful exclusion capabilities of the rsync tool. Through comprehensive operational examples, the article demonstrates the basic syntax of rsync command, usage of --exclude option, relative path handling techniques, and application of dry-run testing mode. Comparative analysis of different methods offers readers complete and practical file management solutions.

This paper provides an in-depth analysis of the "cannot find -lxxx" error encountered when using the g++ linker on Linux systems. Using the libmagic library as a case study, it explains shared library naming conventions, symbolic link mechanisms, and the role of ldconfig. Multiple solutions are presented, including creating symbolic links, using full library filenames, and configuring library search paths, with detailed code examples for each approach. The paper also discusses general diagnostic methods for similar linking issues, offering developers systematic approaches to resolve shared library problems.

This technical paper provides an in-depth analysis of various methods for extracting the last 100 lines from log files in Linux systems. Through comparative analysis of sed command limitations, it focuses on efficient implementations using tail command, including detailed usage of basic syntax tail -100 and standard syntax tail -n 100. Combined with practical application scenarios such as Jenkins log integration and systemd journal queries, the paper offers complete command-line examples and performance optimization recommendations, helping developers and system administrators master efficient techniques for log tail extraction.