Linux

Technical Basics

Layers

[Mostly from lowest to highest:]

• Boot medium: hard disk (HDD), solid-state drive (SSD), flash drive (USB), read-only (CD, DVD), or network.
  
  
• Disk partition table: part of Master Boot Record (MBR) sector,
  or GUID Partition Table (GPT) which is 34 logical blocks.
  
  
• Computer/boot firmware:
  Legacy BIOS (MBR sector has partition table and first-stage bootloader),
  or UEFI (load a file from FAT32 boot partition)
  or coreboot or U-Boot.
  
  
• Boot manager / boot menu / bootloader: usually GRUB, but there are others (Syslinux, LILO, rEFInd, gummiboot, efistub, coreboot, OpenCore (Mac), Clover (Mac), BOOTMGR (Windows), systemd-boot, U-Boot (embedded systems), more). [Also there is a "fallback" bootloader in boot/efi/EFI/BOOT ?] Gives a menu of available kernels/systems, user chooses, it loads that image and jumps to it. At various points in here, there may be decryption of the full disk or a partition.
  
  
• Bootsplash: Plymouth, Splashy, RHGB, XSplash, more.
  
  
• Kernel: handles processes, memory, more. Uses drivers to connect to hardware devices, and modules to implement filesystems and network protocols and security mechanisms and encryption and more.
  Linux kernel map
  Interactive map of Linux kernel
  sleeplessbeastie's "How to display kernel release information"
  
  
  • Kernel type: mainly a matter of config parameters ? Real-time, low-latency, clustering, stripped-down, more ? Could change the process scheduling algorithm or other things. There are various named configurations (AKA "spins"): Zen, Liquorix, GNU Linux-libre, XanMod.
    
    
  • Modules and Drivers:
    "ls /lib/modules/$(uname -r)/kernel/drivers/*/*.ko"
    to see all available modules and drivers.
    "Kernel Modules" section
    Some drivers may contain/install maybe-proprietary "binary blobs" of code which run on CPU or GPU etc: article.
    There also could be a "binary blob" of CPU microcode which is installed inside the CPU to modify the instruction set.
    Do "lsmod" to see installed modules, drivers and filesystem types.
    Do "lspci -nn -k" to see which module/driver each device is using.
    Do "ls /sys/module/MODULENAME/parameters" to see parameters defined for a module.
    Do "sudo cat /sys/module/MODULENAME/parameters/PARAMNAME" to see a parameter value.
    
    
  • Filesystems:
    "ls /lib/modules/$(uname -r)/kernel/fs/*/*.ko"
    to see all available filesystem types.
    
    
  • Kernel parameters:
    "less /boot/config-$(uname -r)"
    "Kernel Parameters" section
    
    
  • System-call API (at assembly-language level):
    Ryan A. Chapman's "Linux System Call Table for x86 64"
    Filippo Valsorda's "Searchable Linux Syscall Table for x86 and x86_64"
    "ausyscall --dump" to list all syscall numbers and names.
    Use syscall to copy arguments across.
    From article:
    On modern Linux some syscalls are not true syscalls. Instead of jumping to the kernel space, which is slow, they remain in userspace and go to a special code page provided by the host kernel. This code page is called vdso. It's visible as a .so library to the program.
    Compound system calls (io_uring): article
    
    
• libc API: glibc, musl, Bionic C (Android), others.
  GNU's "libc - Function and Macro Index"
  
  
• GNU packages/utilities: shell, compiler, libraries, CLI utilities (coreutils: cat, ls, grep, others), more.
  
  
• util-linux utilities: dmesg, fsck, kill, su, others.
  
  
• Init system: systemd, svinit, s6, runit, etc.
  
  
• Windowing/display server protocol: X11, Wayland, Mir, OpenGL ?
  "X" section, "Wayland" section
  "echo $XDG_SESSION_TYPE", "loginctl show-session 2 -p Type", "glxinfo | less"
  
  
• Display server: X.Org Server, XFree86, Wayland compositor (Weston, mutter) ?
  diagram of X and Wayland in same system
  
  
• Window manager: X11 manager (tiling: i3, dwm, bspwm, awesomewm, xmonad; stacking: Fluxbox, Openbox, mutter, muffin, Compiz, Metacity, kwin, xfwm, Gala, Window Maker, JWM), Wayland manager/compositor/more (Weston, sway, Way Cooler, mutter, Enlightenment, Moksha, Wayfire, Hyprland, more) ?
  For more info, see my Linux GUI page.
  
  
• GUI framework/library/toolkit ?: GTK+, Qt, libwayland-client, libX, OpenGL ?
  
  
• App framework/library ?: KDE, GNOME, Unity, more ?
  
  
• Desktop manager (taskbar/systray, application launcher, icons): KDE/Plasma, GNOME, Cinnamon, Xfce, LXDE, more.
  
  

A bundle of choices of the last 4-5 items and some apps usually is called a "Desktop Environment" (DE). See Desktop Environments section.

Distributions (distros)

A distro is a set of choices of layers/parts/policies, all packaged together under one label.

Some major distros: Debian, Ubuntu, Kubuntu, Linux Mint, Red Hat, Fedora, Arch, openSUSE.

Debian Family Tree (!)
Which is just part of a bigger GNU/Linux Distributions Timeline (!!)

My "Linux Distros" page

Other pieces that usually vary by DE

• Display manager / login screen manager: sddm, gdm3, lightdm, KDM, MDM, SLiM, more.
  See Display Managers
  
  
• Themes.
  
  
• System Languages.
  
  
• Fonts.
  
  
• Desktop widgets/launchers/icons/shortcuts. Launchers: dmenu, Synapse, Albert, Ulauncher, more.
  
  
• Taskbar/systray applets.
  
  
• GUI-shell extensions.
  
  
• GUI workspaces (AKA virtual desktops or multiple desktops; article).
  
  
• KDE's GUI activities (desktops with different icons and widgets on each, and then you can have multiple workspaces inside each activity).
  
  

Other pieces that often vary by distro or distro-family

• Installer (Calamares, Ubiquity, Subiquity, curtin, Anaconda, Debian-Installer, YaST, ZuckerBee, Cnchi, Refracta, os-installer, more).
  
  
• System GUI apps:
  • Updater.
  • Software manager/store (snap software-boutique, GNOME Software, KDE Discover, Muon, pamac, AppCenter, MintInstall, more; article1, article2).
  • File manager/explorer (Nautilus, Nemo, Caja, Thunar, Dolphin, Krusader, Pantheon Files, Ranger, ROX, LF, others) and add-ons.
    ("xdg-mime query default inode/directory" to show file manager in use.)
  • Task manager.
  • Crash-reporter (whoopsie, apport, Dr. Konqi, others).
  • Settings manager.
  • Network manager.
  • Disk partitioning/formatting.
  • Screen-saver/locker: XScreenSaver, Light-Locker, GNOME Screensaver, XSecureLock, XLockmore, alock, xtrlock, more.
  • more ...
  
  
• Default user GUI apps:
  • Terminal.
  • Text-editor.
  • Video player.
  • Browser.
  • Image viewer.
  • Image editor.
  • more ...
  
  
• Repositories / App Store: apps and packages that are available for use in this distro.
  
  You'd hope that being in a repo means "has been tested/approved and is supported", but it may just mean "installs and runs without crashing". And various repos for a distro may be provided by various parties; e.g. Ubuntu has 4 repos (the universe and multiverse repositories are "community-maintained").
  
  
• CLI apps.
  
  
• Codecs.
  
  
• Printer drivers: "lpstat -s" to see defined printers; "ls /etc/cups/ppd/*.ppd" to see the installed printer drivers; /usr/lib/cups/driver contains databases of PPD's.
  
  
• Documentation.
  
  

Things that vary less often, or vary only from one distro-family to another:

• Source or binary packages: most are binary; source-based distros include: Gentoo, LFS.
  
  
• Packaging
  
  
• Init/daemon/services system: sysvinit, runit, systemd, BSD-style startup scripts (Slackware), Upstart, Finit, OpenRC (Gentoo), more (also see No systemd; Jesse Smith's "Comparing init systems").
  
  
• Fairly standard daemons/services: Network management (DNS, DHCP, VPN, more), printing (CUPS), network services (FTP, SSH, more).
  
  
• Fairly standard facilities: Authentication (PAM, certificates, more), access control, IPC (D-Bus, sockets, Varlink, more).
  
  

Some other variations or modifications, some of them user choices

• Do you use the command-line much, or mostly stay in the GUI.
  
  
• Does the distribution do "rolling releases" (constantly updating), or do periodic "stable releases" (AKA "point release" or "fixed release"). Rolling release: Arch, Solus, openSUSE, more. Stable release: Ubuntu, Mint, Fedora, Elementary OS. Some distros have both kinds available.
  FOSS Linux's "Linux Rolling Release vs Point Release, and which is better?"
  
  
• There may be different stable, testing, experimental versions of the same distribution.
  
  
• Emphasis / target of distro: desktop GUI, server, VM / container / cloud, micro-VM / unikernel / cloud, IoT, micro-computer (e.g. Raspberry Pi).
  
  
• CPU architecture: x86, ARM, more.
  
  
• 32-bit and 64-bit versions, as on Windows.
  
  
• UEFI Secure Boot ("Secure Boot" section), or not.
  
  
• Kernel / system emphasis: normal, high-availability (clustering), hardened, low-latency (e.g. Ubuntu Studio, Liquorix), real-time, run-as-root (e.g. old Kali), containers/cloud image (e.g. Flatcar), immutable (e.g. Fedora Silverblue/Kinoite, openSUSE MicroOS, SteamOS, Vanilla OS).
  
  
• Disk encryption: full-disk, full-extended-Linux-partition, individual partition encryption, encrypted home directories, or no encryption.
  
  
• Various command-line shells: bash, zsh, fish, dash, tcsh, ash, xonsh, ksh, more.
  
  
• Various GUI docks: Latte, Cairo, Docky, more.
  
  
• Do you compile things yourself from source (Gentoo, LFS, BLFS, more), or use binaries created by other people/companies.
  
  

Roles in the Linux world

• Policy / standards / licensing bodies and corporations.
  
  
• Developers.
  
  
• Packagers.
  
• System administrators.
  
  
• Users.
  
  

More-complicated things you can do

• Partition a disk into Windows and Linux partitions, so you can dual-boot (boot into either OS). A little dangerous; sometimes a Windows update will wipe out the Linux bootloader (only if using MBR ?).
  
  
• Boot Linux, and then sometimes run a Windows emulator (such as WINE) to run some Windows applications.
  
  
• Boot Linux, and then sometimes run a virtual machine (such as VirtualBox) to run a copy of some other OS (Windows, or a different Linux) inside the VM.
  
  
• Boot Windows, and then sometimes run a Linux command-line environment (such as BASH) to do various operations.
  
  
• Boot Windows, and then sometimes run a Linux emulator (such as WSL 1) to run some Linux applications.
  
  
• Boot Windows, and then sometimes run a virtual machine (such as VirtualBox, or WSL 2) to run a copy of some other OS (Linux, or a different Windows) inside the VM.
  
  

Linux Myths

• Linux gives you more security:
  
  Your security depends FAR more on your own behavior than on the specifics of any particular OS or distro. Do backups, use a password manager, turn off services you don't use, use a VPN, use blockers in the browser, keep your software updated, don't install sketchy stuff, don't fall for scams, use a smartphone or something to do a port-scan of your system. Do an anti-virus scan every couple of weeks (yes, Linux can get malware). Make sure other systems on your LAN are maintained properly too. Take all the same precautions you'd take on Windows or a Mac OS.
  
  It is true that Linux users tend to install most apps from a trusted source (their distro's package repo) whereas Windows users have to install from many vendors. So advantage to Linux.
  
  See "Don't expect perfect security just because you're running Linux" section of my "Using Linux" page
  
  
  
• Linux gives you more privacy:
  
  As with security, your privacy depends FAR more on your own behavior than on the specifics of any particular OS or distro. Yes, Windows 10 has a disgusting amount of telemetry, most of which you can turn off. The Windows 10 installer really badgers you to connect to all kinds of cloud services. And Windows Update has a habit of changing settings (article). But if you use Linux and go posting your private info on Facebook or something, Linux is not magically going to give you privacy.
  
  Linux has a bit of what some people call "telemetry": Linux Telemetry section.
  
  
  
• Linux is much faster than Windows 10:
  
  Not my experience. I changed my slow old Dell laptop with 3 GB RAM and spinning hard disk from Windows 10 to Linux Mint 19.0 Cinnamon, and couldn't see any performance difference.
  
  Sometimes people will use Windows 10 for two years, then do a fresh install of Linux and use it for one day, and marvel at how much faster Linux is. Well, load up Linux with apps and services and VPN and browser add-ons and use it for a couple of months, and then see how it feels.
  
  Michael Larabel test on high-end hardware 10/2019 (not much difference, IMO)
  Michael Larabel test on low-end hardware 1/2020 (Ubuntu 20 maybe 15% faster than Win10)
  Michael Larabel test on mid-hardware 6/2020 (Linux maybe 10% faster than Win10)
  
  
  
• Linux is more stable/reliable than Windows 10:
  
  Not my experience (on the desktop). I fought total GUI freezes in Linux Mint for many months. The Windows machines we have don't BSOD, or update in the middle of use. But other people have different experiences.
  
  Kev Quirk's "Is Windows Unstable? Here Are My Thoughts"
  
  
  
• Linux is not Windows:
  
  Linux mostly is the same as Windows, until you get to details.
  
  You can use the same browser and extensions, probably same password manager and VPN and cloud storage, maybe same email client and same backup provider. The GUI file explorers on the two systems are very similar. If you like using PowerShell on Windows, there is the Terminal-and-shell on Linux.
  
  The GUIs both have all the same concepts: desktop with icons, usually a Start button/menu, usually a system tray. Files and folders/directories, applications, disk, RAM, removable storage, menus, dialogs, networks, etc. Log in/out, boot up and shut down. All very similar.
  
  Under the hood, things are very similar too: filesystems, background processes/services, command-line interface, etc. Multi-tasking, multi-threading, etc. Windows no longer has DOS underneath; it has a modern kernel.
  
  Best practices on the two systems are very similar too. Have good backups, don't install sketchy stuff, don't fall for scams. Keep your software updated, use "blockers" in the browser, use a password manager and maybe a VPN. Turn off features you don't use. Don't routinely run as administrator/root, more to avoid catastrophic mistakes than for security. Anti-virus is a bit less important on Linux for now, but the situation is changing, it's a good idea to do a manual scan every week or two.
  
  You won't have to learn all new stuff to use Linux. Details are different, some apps are different. But you can be productive almost right away.
  
  On my old slow limited laptop (3 GB of RAM), Windows 10 and Linux Mint 19 Cinnamon had about the same performance.
  
  
  
• Linux doesn't need anti-virus:
  
  Linux-specific malware is not unknown: Wikipedia's "Linux malware - Threats"
  
  It's not true that you'll only ever see Windows malware on Linux. Programs such as chkrootkit and rkhunter are full of signatures of Linux-specific malware.
  
  And now Linux desktop users are using the same browsers etc as the Windows people are, so threats there are more likely to exist on Linux too. Same with PDF docs and Office macroes. And with cross-platform apps such as those running on Electron or Docker. And libraries (such as the SSL library) used on many/all platforms.
  
  Add to that the growth of the Linux desktop population, and use of Linux in servers and IoT devices, and Linux exploits and malware become more valuable. Expect to see more of them. Practices that have been sufficient for decades may be sufficient no longer.
  
  Some indications of how things are changing:
  Sergiu Gatlan's "New stealthy OrBit malware steals data from Linux devices"
  Lindsey O'Donnell's "Mac, Linux Users Now Targeted by FinSpy Variants"
  Davey Winder's "Linux Security: Chinese State Hackers May Have Compromised 'Holy Grail' Targets Since 2012"
  SOC Prime's "EvilGnome: New Linux Malware Targeting Desktop Users"
  Catalin Cimpanu's "ESET discovers 21 new Linux malware families"
  Sergiu Gatlan's "Linux, Windows Users Targeted With New ACBackdoor Malware"
  BlackBerry's "Decade of the RATs"
  
  I did a scan with Sophos AV (until they dropped their free Linux edition) every couple of weeks. IMO a constantly-running, real-time AV wired into everything is overkill, and risks increasing attack surface and destabilizing apps and the system. Your judgement may differ.
  
  Artem S. Tashkinov's "Linux Myths Series: Linux doesn't Need an Antivirus"
  
  
  
• Windows is malware / spyware:
  
  Windows 10 has a disgusting amount of telemetry, most of which you can turn off. But probably billions of people get great benefit from using Windows. And Microsoft's business model (unlike those of Google and Facebook) is not dependent on selling access to our data. Microsoft makes about 15% of revenue from Windows, and that's from license fees, not selling access to data.
  
  Linux hyper-partisans who take every opportunity to say Windows is "malware" or "spyware" probably are just making Windows users think Linux people are a bit nuts.
  
  
  
• Linux is uniquely powerful because of the CLI, and using CLI makes you l33t:
  
  
  MacOS has a CLI. Windows has CMD and PowerShell and WMIC. Ports of Unix tool packages including such things as csh and grep and sed and awk were available on Windows and DOS 30+ years ago.
  
  If you're administering lots of servers or something, sure, go nuts on the CLI and SSH and tmux etc. Probably 95% of desktop users will never use SSH or tmux, and most will have no need to do anything fancy with the CLI.
  
  See the "The CLI" section of this page.
  
  
  
• Linux has more installations than any other kernel/OS:
  
  No one using Android or a Chromebook thinks "I'm using Linux". MacOS has a heritage of Unix/Mach/NeXTSTEP/BSD, not Linux. iOS and Windows are unique OS's.
  
  And there are some 30 billion IoT devices as of 2020 (article), many of them running some RTOS (likely TRON) instead of Linux.
  
  
  
• Linux is great because you're in control of all the code:
  
  You're running hundreds of millions of lines of code, with plenty of changes every month. There is 25 years or so of decisions and bugs and security vulns and unexpected behaviors lurking in that code. You have only a thin surface of control over it.
  
  Yes, you do have much more control than you would in Windows or MacOS. Especially when it comes to seeing the code and filing/seeing bug reports.
  
  
  
• Everything on Linux is open-source:
  
  No. The firmware or microcode loaded into CPU, GPU, other devices probably is closed-source. The hardware (CPU, GPU, etc) probably is closed-source. Online services you'll use (e.g. GMail, VPN, DropBox, etc) probably are closed-source. Some CODECs. Desktop apps such as Opera, Skype, Adobe Reader. Enterprise apps such as Oracle or SAP or PeopleSoft.
  
  
  
• Linux is great because you can spend all your time customizing the GUI:
  
  Sure, if you're into "ricing" and adding docks and launchers and tweaking wallpapers and icons etc, have fun. You can do a lot of that on Windows, too.
  
  Personally, I don't do any of that on any OS. I live all day in some major applications (browser, source-editor, IDE, password manager, email client, image-editor, file explorer) and almost never even see the desktop, much less use it. The system is a tool. I don't want to spend all my time tweaking the system.
  
  Also, the more modifications you do, the harder it gets to report bugs. The first thing any dev will ask you to do is test again with all extensions and mods removed.
  
  
  
• Microsoft totally hates Linux and wants to destroy it:
  
  Microsoft has ported/supported PowerShell on Linux, VS Code on Linux, Microsoft Teams on Linux, Skype on Linux, SQL Server on Linux. As well as going the other direction: WSL on Windows. And now they own GitHub, a mainstay of open-source software. The new Chromium-based Edge browser will come to Linux.
  
  As of 2015, Microsoft managed several hundred thousand Linux or Unix servers for its customers (MS blog article).
  
  Windows is about 15% of Microsoft's revenue. Microsoft will earn money anywhere it can.
  
  Microsoft is hugely profitable and successful. I doubt they fear Linux.
  
  
  
  

Linux Truths / Benefits

• Linux gives you more privacy from Microsoft:
  
  Windows 10 has a disgusting amount of telemetry, most of which you can turn off. Linux and open-source software has far less telemetry, and it's much easier to verify that turning it off really turns it off.
  
  
  
• Linux gives you more choice:
  
  There's no doubt that some 400 Linux distros using probably 20 different desktop environments and 10 or 15 package managers gives you a lot more choice at the OS / system level than Windows 10 does.
  
  It's not clear to me that Linux users have more choice at the application level. Plenty of proprietary Windows/Mac apps do not run on Linux.
  
  It's not clear to me that Linux users have more choice at the hardware level. Plenty of hardware vendors support Windows/Mac a lot better than they support Linux.
  
  See the "Fragmentation" section of my "Linux Problems" page.
  
  
  
• Linux can run in much less RAM than Windows 10:
  
  True, but maybe because the stripped version(s) of Windows (WinPE ?) are not available to the public, they're special-license only for use in things such as kiosks and ATMs.
  
  And using RAM is not a bad thing; it's there to be used.
  Help ! Linux ate my RAM ! (but see PR)
  
  You want low "free" memory and plenty of "available" memory:
  Hayden James' "Free vs. Available Memory in Linux"
  
  
  
• Linux is easier to test-drive:
  
  You can boot a Linux "live session" from a USB stick, and do useful stuff with it.
  
  
  
• Linux updates much better than Windows:
  
  Linux gives you much more control over when and what you update (but for Windows see InControl). And somehow Windows updates have gotten far slower starting around the 2020 timeframe; in my experience on two laptops, it can take 30 to 60 minutes or more to do a Windows update. And in 2021, Windows has had a series of updates that contain more bugs (mainly on enterprise stuff such as PrintNightmare).
  
  
  
• Linux is better for learning software and programming:
  
  Since Linux has an open-source orientation, it's far easier to see how an application or a library or OS module works, than in Windows or Mac. It's far easier to see the whole stack from user down to hardware and back up to user. Most things are pretty well documented.
  
  On the other hand, Linux tends to have an "add instead of replace" mentality, so you if you try to trace through a particular stack (e.g. how DNS works), you will find three somewhat-separate sets of code in there, maybe with two of them disabled or overridden by the third. It can be a mess. Windows internals may be worse, macOS internals may be better, I don't know.
  
  Since most web servers and many other servers are running Linux, it's easier to understand how servers work if you're using a Linux desktop. And in many cases you can run the same server software right on your desktop machine.
  
  It is very nice that the bug-reporting systems generally are open, too. In Windows as a normal user, if you report a bug, the report disappears into Microsoft and is never seen again. In Linux, you can track reports, discuss with devs, see results.
  
  
  
• Linux scales more:
  
  Linux is used on everything from Raspberry Pi to IoT devices to phones to desktops to servers to supercomputers. Same is not true of Windows and Mac, although you do find Windows in ATMs and vending machines and other odd places.
  
  
  

Miscellaneous

Standards / projects / groups

• GNOME: desktop environment and applications for it.
  Wikipedia's "GNOME"
  
  
• KDE: makes Plasma Desktop, Frameworks, Okular, Krita, digiKam, more.
  I'm told it consists of more than 200 apps and some 2600 source projects.
  Wikipedia's "KDE"
  Blue Systems
  
  
• Qt Company: makes the Qt framework, which is used by KDE and others.
  
  
• freedesktop.org: free software desktop environments, including Cairo, Mesa 3D, Wayland, X Window System, D-Bus, clipboard, libinput, PulseAudio, systemd.
  Wikipedia's "freedesktop.org"
  
  
• POSIX: family of standards for APIs and command line shells and utility interfaces for Unix etc.
  Wikipedia's "POSIX"
  
  
• Linux Foundation: standardize and promote Linux. Among many other projects, had a role in starting Node.js Foundation and OpenJS Foundation.
  The Linux Foundation
  Wikipedia's "Linux Foundation"
  
  
• GNU: free operating system utilities.
  Wikipedia's "GNU Project"
  Ariadna Vigo's "What the GNU?"
  Note: Linux distros such as Alpine and Chimera don't use GNU utilities.
  
  
• kernel.org: the kernel project, run by Linus Torvalds, and util-linux utilities.
  The Linux Kernel Archives
  Wikipedia's "kernel.org"
  
  
• X.Org Foundation: open accelerated graphics stack, including DRM, Mesa 3D, Wayland, X Window System.
  Wikipedia's "X.Org Foundation"
  
  
• Free Software Foundation (FSF): supports the free software movement; projects include GNU, Coreboot.
  Wikipedia's "Free Software Foundation"
  
  
• LLVM Developer Group: compiler and related toolchain technology.
  Wikipedia's "LLVM"
  
  
• Linux Userspace API (UAPI) Group: feature ideas and specs, mostly at firmware/boot level.
  The Linux Userspace API (UAPI) Group
  
  
• Red Hat: various distros, creating rpm and NetworkManager, plus sponsoring Fedora Project, and contributing to GNOME, LibreOffice, radeon, nouveau.
  Wikipedia's "Red Hat"
  Now owned by IBM.
  Christian F. K. Schaller's "Fedora Workstation: Our Vision for Linux Desktop"
  
  
• Canonical: various distros, creating Mir, snaps, Launchpad, plus contributing to Linaro.
  Wikipedia's "Canonical (company)"
  
  
• Linaro: contributes to the Linux kernel, GCC, power management, graphics and multimedia interfaces for ARM.
  Wikipedia's "Linaro"
  
  
• The Debian Project: various distros, and spawned the organization "Software in the Public Interest".
  Wikipedia's "Debian"
  
  
• The openSUSE Project: openSUSE distros, and tools including Open Build Service, KIWI, YaST, openQA, more.
  Wikipedia's "The openSUSE Project"
  And company SUSE developing and selling the commercial version of SUSE.
  
  
• The Fedora Project:
  While True Do's "Fedora - Overview"
  
  

Plenty of huge companies (Intel, Microsoft, Google, Samsung, more) and smaller companies/foundations (Mozilla, Apache, more) contribute code and/or money to Linux and FOSS.
Statistics & Data's "Top Companies Contributing to Open Source - 2011/2021"

Some subsystems have come from various corporations: CUPS (Apple sort of), ZFS (Oracle).

Unix Family Tree 1
Unix Family Tree 2

From Alan Pope's "Pitchforks set to Stun":

The 'community' of Linux users has a bit of a problem. It's not really a community at all. The Linux 'community' is a bunch of individuals who have an affinity for running the OS. ...

... there's no real wider unified 'Free Software' community either. There's the "Popular People's Front of FSF" and the "People's Popular Front of Open Source" who believe fundamentally different things and target different users. It's a giant sliding scale, ...

Difference between Free Software and Open Source, by South Park Goth kids (video)

Software / business models

• Open-Source: original software source code is published for anyone to see and use. It's considered good behavior to take any changes you make, open-source them, and offer them to the upstream project to help improve the base software.
  
  
• Free: any changes to software source code must be published for anyone to see and use.
  
  
• Open-Core: [definition is contested ?] uses open-source software at the core and then adds proprietary software around that.
  
  

Note that these really are talking about software (not services, or trademarks). Examples: Linux kernel is open-source but the name "Linux" is trademarked. Red Hat's software is open-source but the company sells support services and owns various trademarks. Canonical (Ubuntu) is open-source but sells certification services, support services, management services, and owns various trademarks.

Each project or company may have secret information (encryption keys, operating procedures, customer data, financial, etc) even though the software is free or open-source.

The CLI (terminal-and-shell; Command-Line Interface)

From procabiak comment on Guide: Migrating to Linux in 2019:

Stop recommending the command line to beginners. Disclaimer/TL;DR: I like the command line, use it every day, but it's not the user-friendly tool you make it out to be. It's a tool for veterans, power users, tech-savvy folk. It's dangerous in the wrong hands.

This is a Linux/nix culture we need to move away from if Linux is to be successful mainstream. There's a reason many distros have a GUI for package management. If everything was indeed easier on a command line for every user demographic, why waste time implementing the GUI package manager, just tell everyone to use the terminal, right? Wrong! (IMO)

There're people who don't speak English or have difficulty with spelling even the simplest words, people with typing disabilities, older aged people, children ... Just to name a few, but all who just want to enjoy a game without needing to learn the complexities of Linux or us vets pushing that need onto them.

With a GUI package manager, you don't need to know anything beyond the ability to explore, click around to find stuff you need, etc. Often times you'll find other software you didn't think about wanting. The guide already states package managers are akin to app stores. These days everyone knows what an app store is (well, I make the assumption - there are people who have never owned smartphones before), so it's not as difficult a concept as it used to be, so we can use fewer words to explain it. The instructions are pretty simple: "open the package manager (app store) from the menu, search for steam and click install, enter your password and click OK". It's not faster than a command line, but it's simpler for many people. The instruction is nearly universal for all distros, even if the GUI looks or behaves slightly differently.

Contrast with apt, yum or pacman. You'd also need to learn to use grep to get anything remotely useful out of their list-package outputs. You can't explore - you just execute a command like sheep and hope you really just installed steam from Valve and not some other kind of steam. And when it comes to instructions, you need more words to explain the command line (that many people are omitting): "open the Terminal, type sudo apt install steam, type in your password (it shows up blank but your password is really there, keep typing), press enter, then type Y and press enter" ... Not only that, that command only works for Debian-based distros using apt. It will confuse Fedora and Manjaro novices using yum or pacman (they might even try to install apt, just to be able to run your command!).

You can also very easily mislead a novice to run dangerous "sudo rm -rf /"-like commands. I assume it's backwards to suggest to the user to understand the command before executing it when they are learning the command in the first place, so we can't assume the novice user will know what every command does. Therefore I can maliciously explain that line means "sudo = as a superuser, rm = remind me, -rf = to read from, / = root", for example. If I am their only reading material, I've just tricked a user to wipe their OS, imagine what else you can do to that novice by exploiting shortly-named commands?

The reality is command lines are simpler for the person offering help, but not necessarily for the person on the other end.

From grady_vuckovic comment on Guide: Migrating to Linux in 2019:

I have experience in converting people to Linux and that terminal is absolutely poison. When I show a typical Windows user an OS like Linux Mint, they are interested until they see the terminal, then groan and lose interest immediately.

Even if GUIs change, it is still waaaay easier for a new user to figure out a GUI with obviously labelled buttons, text boxes and tabs, than figure out how to use a terminal.

Try to put yourself in the mindset of a person who has only ever used a computer for homework, Facebook, job-hunting, Amazon, and who mainly uses a smartphone for all their computer needs. A terminal itself is a foreign concept and not a pleasant one.

On most decent software managers for Linux distros, the GUI is mostly pretty self-explanatory, with a simple search box for finding new software. That's pretty easy for a new user to figure out how to use.

But it is almost impossible for them to figure out what 'sudo apt steam' means at a glance, (and no, taking the time to explain it doesn't help, it will likely result in a 'wait wait I just want to install an app, why do I need to know all this rubbish?') or figure out where they need to go to type it, because if your user doesn't know where the software manager is, they certainly don't know where the terminal is or how to use it, so for all you know they could end up typing those commands into a search box somewhere. Not to mention it's difficult for them to even remember something like that.

And when I say "how to use it" regarding the terminal, I mean that literally. I've seen new users half type in commands, causing the terminal to enter a mode of waiting for the rest of the input of the command, then they can't figure out why it isn't working as they type in more and more commands, and other frustrations. It is truly a TERRIBLE user experience and one that should only be reserved for veteran Linux users.

Also keep in mind, users like to install and uninstall software, how on Earth is a user meant to figure out how to uninstall software which they installed with 'sudo apt'? There's no list of installed software they can look at, no buttons to click, no GUI to navigate, all they can do is hopelessly start Googling for help on how to use apt commands (that's an appallingly bad user experience for someone new to Linux) or (more likely) just get frustrated and decide "Linux is rubbish!" and switch back to whatever they were using before.

On top of that, it looks pathetically antiquated in 2019 to use a terminal to do such a simple basic OS operation as installing software or installing some drivers.

It may be easier for you to give instructions in terminal commands, and the terminal may be easier for you to use than a GUI, but it is scaring away possible Linux converts. For Ubuntu at least you should include instructions on how to navigate to the Software Manager.

I personally wouldn't offer any advice at all for Linux newbies that includes terminal commands unless you're trying to scare them away from Linux.

My thoughts:

• Recognition (seeing something in GUI and recognizing it's what they want) is easier than recall (knowing what they want to do, and then recalling what command does it) for most people.
  
  
• CLI is the right tool for certain things, such as piping commands together to do text-manipulation.
  
  
• CLI is great for documenting procedures, can be copy-pasted, can be used through SSH, even can be spoken to someone.
  
  
• CLI can be faster for experienced users.
  
  
• CLI is more standard (across distros) than GUIs.
  
  
• CLI is always same language, while GUIs can be in any human language.
  
  
• Windows and Mac also have CLI's, so this is not an advantage or selling-point for trying to move people to Linux. Heck, DOS had ONLY a CLI. And the Unix CLI commands have been available for DOS and for Windows CLI for a long time; you can use grep and sed etc on any of those CLI's, with the right stuff installed.
  
  
• Many times when you search for the solution to some problem, the answer will be couched in the most cross-distro way: giving terminal commands. It's kind of hard to avoid the terminal in Linux, even if you want to.
  
  Sure, smoother distros such as Ubuntu-family may give fewer problems. And some articles go to the trouble of walking you through a GUI-only solution, giving screenshots. But many solutions will be given as CLI.
  
  

"GUI versus CLI is a silly thing to debate. It's like debating if legs or arms are more useful. You're better off with both arms and legs."

'Terminal' is not same as 'shell'

Types:

• Terminal is the GUI process (window controls, tab stops, copy/paste, drag/drop, font, background image/color, line-buffer, scrolling, multiple panes, char color, more).
  
  
• Shell is the text-command process (variables, statements, pipes/redirection, launch commands, path, history, tab-completion, more).
  
  
• CLI is Command-Line Interface, basically "commands you can run in the shell".
  
  
• (Virtual) Console (accessible via ctrl+alt+F1 etc) is a text-window process (line-buffer). Device name /dev/tty*.
  
  
• Pseudo-Terminal (PTY) Device names /dev/ptm* and /dev/pts*.
  
  

Examples:

• Terminal: gnome-terminal, xfce4-terminal, konsole, guake, rxvt-unicode, aterm, xterm, kitty, alacritty, tilix, terminator, tmux, PuTTY, termite, sakura, urxvt, st, foot, cool-retro-term, tabby, screen, more.
  
  
• Shell: sh, csh, bash, fish, zsh, ksh, ash, dash, xonsh, more. "cat /etc/shells".
  
  
• CLI: can run "echo hello >>file1".
  
  
• (Virtual) Console: done through getty, agetty, more.
  
  
• Pseudo-Terminal (PTY) terminal running in user space.
  
  

Aram Drevekenin's "Anatomy of a Terminal Emulator"
Seth Kenlon's "Terminals, shells, consoles, and command lines"
Unix Sheikh's "The terminal, the console and the shell - what are they?"
Andreas Fuhrich's "What is the difference: terminal / console / shell?"
Hiks Gerganov's "What do PTY and TTY Mean?"
The Valuable Dev's "A Guide to the Terminal, Console, and Shell"
Viacheslav Biriukov's "Terminals and pseudoterminals"
Linus Akesson's "The TTY demystified"
Chris Siebenmann's "A surprise: you can only have one Linux kernel serial console"
Julia Evans' "Some terminal frustrations"


GUI Terminal:
A pseudo-terminal (pty) is a pair of char-device files which serves as a bidirectional pipe between terminal and shell.
See current pty and shell: "ps -p $$"
See terminal process: "ps -ax | grep terminal | grep -v grep"
Type of terminal to emulate ? "echo $TERM"


Similar happens in a (Virtual) Console:
A tty a char-device file connects console (text window) and shell.
See current tty and shell: "ps -p $$"



A multiplexer has one terminal controlling multiple sessions. Tmux uses a client/server architecture that lets one terminal control multiple sessions on a remote host. Terminator is a terminal that can control multiple sessions on the local host.

"Console" versus "Virtual TTY"

From /u/aioeu on reddit:

There are at least three different things to consider here:

1. The kernel knows how to drive a video adapter. It can run the hardware in a text mode (e.g. a VGA text mode) or in a graphical mode (the framebuffer).
   
   
2. The kernel's virtual TTY subsystem associates a video adapter with a keyboard device and provides the kernel's built-in VT102 emulator. This is probably the thing you think of when running Linux in a text-only mode. It's the thing that provides the multiple screen buffers you switch between using Ctrl+Alt+Fn.
   
   
3. Quite separately, the kernel always has a "console device" of some kind. The purpose of this console is to be somewhere for the kernel to log messages.
   
   

It should be emphasized that these three things are fairly independent. For instance, it is possible to run a system without the virtual TTY. You might use a userspace TTY implementation instead, or you might not care about having an interactive terminal at all.

Regarding point 3, although most people just use a video adapter as the kernel console, you can choose to use something else instead. For instance, you can boot the kernel and have it use a serial port as its console. You can have it shipped over the network to another machine. You can even use multiple output devices as "the" console: you can have the kernel output log messages to both a video adapter and a serial port, for example.

...

To a large extent, this is a big problem with naming. It's an utter mess. The virtual TTY, for instance, is often also called a "virtual terminal", and indeed the kernel config option for it (CONFIG_VT) is named with that in mind. But then this kernel subsystem goes and creates /dev/vcs* devices, and the documentation for that calls it a "virtual console". So who knows?

To make this more concrete, consider these two statements:

• I entered my username and password at the console.
  
  
• The kernel logged a message to the console.
  
  

Both reasonable sentences ... until you realise that the word "console" is being used to denote two completely different things. They only look like the same thing because they happen to be going through the same hardware device.

I guess my point is that you really do need to read between the lines when interpreting articles ... My earlier comment was my description at how these components fit together. I deliberately did not use the names "virtual console" and "Linux console", because different people interpret them different ways.

Expression of Change's "CLIs are reified UIs"
Fernando Borretti's "Shells are Two Thingss"

John Hammond's "How to move FAST in the Linux Terminal" (video)

Cool feature: in KDE's Dolphin file manager, press F4 to open a Terminal that will change dirs as you change dirs in Dolphin.

How to change default terminal,
from someone on reddit:
"[GNOME] Unfortunately, there is no 'default terminal' setting. GLib has a hardcoded list that is used for launching .desktop files marked Terminal=true. [You have to uninstall unwanted terminals.]"
[Maybe you could just replace /usr/bin/gnome-terminal with a link to your desired terminal ?]

Change console settings during pre-kernel part of boot:
See if bootloader config file supports "vga=" parameter.

Change console settings during kernel part of boot:
Try kernel command line "vga=nomodeset" parameter.

Change terminal and console settings:
"man setupcon"
"man console-setup"
Edit /etc/defaults/console-setup or $HOME/.console-setup and then run "setupcon"
Or see /etc/console-setup/*
Or: "setfont" or "setconsolefont", edit /etc/rc.d/rc.font, see /usr/share/kbd/consolefonts
Or: look in /etc/fonts/conf.d

Change terminal settings (not console):
Edit Exec line in Terminal's file in /usr/share/applications, or make overriding file in $HOME/.local/share/applications