The main editors: Vi / Emacs
Window Managers Polybar/Rofi virtman/QEMU dotfiles
systemd runit
GNU coreutils / util-linux bash
General Knowledge
Xorg, Wayland, XWayland Window Managers, X Compositors, Desktop Environments Freetype Font Renderer xinitrc, xsession, startx ALSA, V4L2, pulseaudio, JACK, pipewire XDG-Autostart, XDG Base Specifications (Freedesktop Specifications, Formerly XDG) LSB Filesystem Heirarchy Specification fstab, mount, mkfs, parted, fdisk, fsck, btrfs-progs, chroot, ifconfig, iptables, dd, tar External Programs: ss, ps, pstree, dig, 7z Processes, Daemons, Buses, Sockets, Addresses, Ports, IPC Firewall, SELinux, AppArmor Users, Groups and File Permissions OS Specific: Package Management D-Bus, udisks, gvfs, fuse, udev (systemd-udevd/eu-udev), logind (systemd-logind/elogind), Polkit grub, efibootmgr, initramfs, vmlinuz Video Drivers, Kernel Modesetting, DRM, Mesa, OpenGL, Vulkan Credential Managers: GNOME Keyring, KDE Wallet
Basic GUI Apps: File Managers (Nautilus, Nemo, Dolphin, Thunar) Package Manager Frontends (Software Center, Discover, Pamac, YaST)
Developent Knowledge
GUI Frameworks: Qt, GTK Static Link Libraries, Dynamic Link Libraries, Build Systems, Build Configurations, Compilers Assembly, Processors, Logic Gates, Boolean Algebra Containers, Virtual Machines, Emulators, VT-x/AMD-V Cryptography, RSA, ECDSA, Blowfish, GPG, PGP