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linux

Linux operating system and commands

NetworkingWhy iptables -C Fails 'Bad Rule' on NAT PREROUTING REDIRECT

Fix iptables -C 'Bad rule (does a matching rule exist?)' error for NAT PREROUTING REDIRECT rules visible in -t nat -L. Learn table mismatch, --to-ports syntax, hostname resolution, nftables issues, and exact verification with -S and iptables-save.

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DatabasesView Live MySQL Queries on Linux: Real-time Monitoring Guide

Learn how to view live MySQL queries on Linux using mysql show processlist, performance schema, and query logging. Monitor database activity in real-time for optimization and troubleshooting.

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OSCp Create Parent Directory Linux: Fix No Such File Error

Learn how to make cp create parent directories in Linux automatically. Fix 'no such file or directory' errors using mkdir -p with cp, install -D, or rsync -R for seamless file copying to non-existent paths.

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OSVS Code Linux: ~/.vscode vs ~/.config/Code Files

Discover VS Code on Linux: ~/.config/Code holds settings.json, keybindings, and caches; ~/.vscode stores extensions. Safe deletion guide, what regenerates, reset steps, and management tips for troubleshooting and cleanup.

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ProgrammingHow to Download Java JDK on Linux Using wget - Bypass License

Learn how to download Java JDK on Linux using wget by bypassing Oracle's license page. Step-by-step methods with cookie headers and installation guide.

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OSUbuntu Passwordless Security Risks Single-User System

Explore security vulnerabilities and privilege escalation risks of disabling passwords on single-user Ubuntu without remote access. Analysis shows no new remote threats, physical access remains key concern with sudo NOPASSWD.

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Networkingiptables NAT Rule Check: Why -C Command Fails

Learn why iptables -C command fails to recognize NAT rules and how to properly verify iptables NAT rules using the correct syntax with -t nat option.

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OSBest Open-Source Speech-to-Text Tools for Linux

Discover the top open-source speech-to-text tools for Linux with excellent Russian and English recognition accuracy. Learn which solutions guarantee complete data privacy.

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OSFix Alt Linux 11 WiFi Not Detected After Install

Resolve Alt Linux Server 11 GNOME WiFi adapter not found issue. Change NM_CONTROLLED=yes in /etc/net/ifaces, diagnose with lspci, dmesg, nmcli. Safe fix for NetworkManager unmanaged interfaces.

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ProgrammingWhat Does ^M Mean in Vim? Remove from .vimrc File

Discover what the ^M character means in Vim—it's a carriage return from Windows CRLF line endings. Learn to remove ^M from .vimrc files using :%s/\r//g, :set ff=unix, or dos2unix to fix configuration issues and ensure Unix compatibility.

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OSRun Cron Jobs After Sleep: Systemd Timers & Linux Backup

Ensure cron jobs run if PC sleeps using systemd timers with Persistent=true or anacron. Set up Time Machine-style versioned backups on Linux with Timeshift, rsync snapshots for incremental file versioning after wake-up.

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OSFix Chroot Ubuntu 'No Files Below /bin/bash' Error

Learn why sudo chroot /mnt /bin/bash fails on Ubuntu with 'no files below /bin/bash' error. Fix by bind mounting /dev, /proc, /sys, /run, checking libraries with ldd, and copying resolv.conf. Step-by-step guide for chroot Ubuntu setups.

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ProgrammingHow Linux build system links built-in.a into vmlinux

How the Linux kernel build system uses built-in.a and KBUILD_VMLINUX_LIBS to link object files into vmlinux, and how built-in drivers differ from modules.

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NetworkingIptables: Drop wg0 Packets Except UDP 51821 (ACCEPT vs Negate)

Master iptables rules for WireGuard wg0: drop all incoming packets except UDP port 51821. Why ACCEPT+DROP beats single negated rule. Avoid pitfalls like negation logic, rule ordering, connection tracking, INPUT vs FORWARD chains.

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ProgrammingDetect System Clock Tampering in C++20 with std::chrono

Learn to detect system clock tampering and time jumps in C++20 for cross-platform security agents. Use std::chrono::system_clock vs steady_clock polling, Windows Event ID 4616, Linux timerfd for reliable protection against clock manipulation.

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ProgrammingJxBrowser Chromium Huge VIRT on Linux: Causes & Limits

Why JxBrowser's Chromium subprocesses show massive VIRT (32GB-1TB+) on Linux in top, VIRT vs RSS explained, and fixes: Chromium flags via EngineOptions, ulimit, cgroups, /dev/shm for Docker to prevent JavaFX JVM crashes.

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ProgrammingWhy Ollama Embeddings Slow on Linux VM ChromaDB Posthog

Fix slow Ollama embeddings in ChromaDB on Linux VM without CUDA: batch requests, disable Posthog telemetry, ignore benign warnings. Run fully local for privacy and speed up email embedding performance.

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HardwareConvert SAS Drive 520 to 512 Sector Size: HGST Guide

Step-by-step guide to reformat HGST HUS723020ALS640 SAS drive from 520-byte to 512-byte sector size. Use IT-mode HBA, sg_format from sg3_utils, vendor tools. Hardware needs, RAID vs HBA, firmware risks explained.

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OSInstall Gosplugin on Debian 12 Yandex Browser Guide

Step-by-step guide to install and configure Gosplugin on Debian 12 with Yandex Browser for Gosuslugi access using electronic signatures. Fix infinite download loops, native messaging, and CryptoPro integration.

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DevOpsFix SSH 'Permissions Too Open' Error: id_rsa chmod 600

Resolve SSH 'Permissions 0777 for id_rsa are too open' error. Set correct permissions: chmod 600 ~/.ssh/id_rsa, 700 ~/.ssh on Linux/macOS. Windows icacls fix included. Secure private keys properly.

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