https://penguin-gym-linux.com/en/ A learning web app for Linux command beginners. Latest learning articles. en Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/choosing-a-shell-zsh-fish https://penguin-gym-linux.com/en/articles/guides/choosing-a-shell-zsh-fish Deciding whether to switch from bash to zsh or fish — when it is worth it, migration steps, config tips, compatibility traps, and how to roll back. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/containers-vs-vms https://penguin-gym-linux.com/en/articles/guides/containers-vs-vms Containers vs virtual machines explained. How kernel sharing, namespaces, and cgroups create the speed-versus-isolation trade-off before you learn Docker. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/dev-environment-setup https://penguin-gym-linux.com/en/articles/guides/dev-environment-setup A practical guide to setting up a Linux dev environment fast: package manager, editor, shell, Git, and SSH keys — the essential tools to install first. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/editor-comparison-vim-nano-emacs https://penguin-gym-linux.com/en/articles/guides/editor-comparison-vim-nano-emacs Compare vim, nano, emacs, and VS Code for beginners. Learn each editor's strengths, learning curve, and which one to start with first. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/file-permissions-mental-model https://penguin-gym-linux.com/en/articles/guides/file-permissions-mental-model Build a mental model for Linux permissions. Understand owner/group/other, the rwx (read/write/execute) bits, and how to read the 10 characters of ls -l. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/how-linux-boots https://penguin-gym-linux.com/en/articles/guides/how-linux-boots Understand the Linux boot process step by step. Firmware (BIOS/UEFI), GRUB, kernel, initramfs, systemd, and login, plus how to diagnose each stage. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/linux-distro-comparison https://penguin-gym-linux.com/en/articles/guides/linux-distro-comparison Compare Ubuntu, Debian, Rocky, and Arch by release model, support window, and package family. Pick the right distro for your use case without second-guessing. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/linux-filesystem-types https://penguin-gym-linux.com/en/articles/guides/linux-filesystem-types Compare the ext4, xfs, and btrfs filesystems on Linux. Learn CoW, snapshots, resize limits, and how to check your filesystem with df -T and lsblk. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/package-manager-overview https://penguin-gym-linux.com/en/articles/guides/package-manager-overview One map of apt, dnf, pacman, and zypper. Compare update, install, search, and remove commands across the Debian, Fedora, Arch, and openSUSE families. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/process-states-lifecycle https://penguin-gym-linux.com/en/articles/guides/process-states-lifecycle Learn Linux process states. What ps R / S / D / T / Z mean, the lifecycle from fork to exit and reap, and the truth about zombie and orphan processes. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/root-vs-sudo-concept https://penguin-gym-linux.com/en/articles/guides/root-vs-sudo-concept Understand root vs sudo as a beginner. Learn why you shouldn't work as root, how sudo borrows privileges for one command, su vs sudo, and least privilege. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/ssh-key-vs-password-concept https://penguin-gym-linux.com/en/articles/guides/ssh-key-vs-password-concept Why SSH key authentication beats passwords. Learn the public-key crypto behind it, plus how to create keys with ssh-keygen and disable password login. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/guides/text-encoding-utf8 https://penguin-gym-linux.com/en/articles/guides/text-encoding-utf8 Understand character encoding and UTF-8, why mojibake (garbled text) happens, and how to check and convert encodings with file, iconv, nkf, and locale. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/troubleshooting/bash-command-not-found-path https://penguin-gym-linux.com/en/articles/troubleshooting/bash-command-not-found-path Fix command not found for your own scripts. Tell it apart from Permission denied, run with ./, chmod +x, add to PATH, and clear the bash hash cache. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/troubleshooting/cannot-allocate-memory https://penguin-gym-linux.com/en/articles/troubleshooting/cannot-allocate-memory Fix "Cannot allocate memory" (ENOMEM) even when RAM looks free. Diagnose overcommit accounting, ulimit, and max_map_count, then fix it permanently. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/troubleshooting/cannot-stat-no-such-file https://penguin-gym-linux.com/en/articles/troubleshooting/cannot-stat-no-such-file Why ls shows a file but you still get No such file or directory. Pinpoint hidden characters, CRLF, broken symlinks, and a missing dynamic linker, then fix it. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/troubleshooting/clock-skew-certificate https://penguin-gym-linux.com/en/articles/troubleshooting/clock-skew-certificate Diagnose "Clock skew detected" build warnings and "certificate is not yet valid" errors caused by a wrong clock. Verify with date/openssl and fix it for good. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/troubleshooting/connection-timed-out https://penguin-gym-linux.com/en/articles/troubleshooting/connection-timed-out Diagnose "Connection timed out" (ETIMEDOUT) on Linux. Tell a silent firewall DROP, an unopened security group, a dead service, and a path blackhole apart. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/troubleshooting/device-or-resource-busy https://penguin-gym-linux.com/en/articles/troubleshooting/device-or-resource-busy When umount fails with "device is busy" or "target is busy", find which process holds the filesystem with fuser/lsof and detach it safely. Sat, 06 Jun 2026 00:00:00 GMT https://penguin-gym-linux.com/en/articles/troubleshooting/filesystem-corruption-fsck https://penguin-gym-linux.com/en/articles/troubleshooting/filesystem-corruption-fsck Repair ext4 filesystem corruption safely with fsck. Covers why you must unmount first, how to check the root FS, -n/-y/-f options, and XFS differences. Sat, 06 Jun 2026 00:00:00 GMT