What is Linux?

Linux is a UNIX® clone OS based on MINIX, created in 1991 by Linus Torvalds from the University of Helsinki. Torvalds controls all changes and releases of the Linux kernel.

For close to three decades, Linux has been one of the most commonly used and most reliable OSs for servers in the market, no matter what paid third-party reports that are plaguing the internet indicate.

Most Linux distributions include a collection of programs that run on the Linux kernel like X, KDE, GNOME, Cinnamon or other desktop environments as well as LibreOffice and other office or home utilities. Under the Linux name, you can get RHEL (paid subscription, enterprise licensing), Fedora, CentOS, Ubuntu, Mint (currently my distribution of choice), Mandriva, Debian, Slackware and many others. When Linux became popular (c. 1995-99), you could buy disks for any distribution from the developers or third-party vendors. Nowadays you would most likely download the distribution of your choice as an .ISO and burn it to USB drive.

          
          dd if=linux_image.iso of=/dev/sdb1
        

Shells

Because there many distros in the market (mostly based on a parent distro — for example, Linux Mint based on Ubuntu, which is based on Debian — learning Linux is not necessarily learning how to use the GUI installed in the distro of your choice. Learning Linux is learning how to operate the command language interpreter or shell. Just like the number of distros, there are several shells available for UNIX® and Unix-like OSs.

  • Bourne shell (sh) was developed by Stephen Bourne for Bell Labs in 1979 for Version 7 Unix. The prompt is $ in user mode (user@foobar:~$) and # as root using sudo -i (root@foobar:~#).

    • Bourne Again shell (bash) was developed by Brian Fox for the GNU Project in 1989 as a replacement of the 1979 Bourne shell. It "incorporates useful features from the Korn shell (ksh) and the C shell (csh)" (GNU Project, Sep. 2020). Bash is the most used and most commonly pre-installed in many Linux distributions. This is the shell that I have used most and therefore I am most comfortable with.

      By Emx -
                Wikimedia Foundation, GPL,
                https://commons.wikimedia.org/w/index.php?curid=509725

    • KornShell (ksh) was developed by David Korn for Bell Labs in 1983. It is backward compatible with bash and partially compatible with C shell.

      By Huihermit — Own work, Public Domain,
                https://commons.wikimedia.org/w/index.php?curid=30558744

    • Almquist shell (ash) was developed by Kenneth Almquist in 1989 as a replacement for the Bourne shell in System V4 (BSD).

      • Debian Almquist shell (dash) is the Debian version of ash developed by Herbert Xu in 1997. dash became the default shell in Debian GNU/Linux and Debian-based distributions like Ubuntu for boot sequence.

  • C shell (csh) was developed by Bill Joy in 1978 for 2BSD. The prompt is % in user mode.

    • TENEX/TOPS C shell (tcsh, pronounced tish) was developed by Ken Greer at Carnegie Mellon University in 1975 and merged tcsh into csh in 1981. Mike Ellis at Fairchild A.I. Labs expanded tcsh with command competition in 1983. Other key developers include Paul Placeway and Christos Zoulas. It is backward compatible with csh.

      By iluxa777 — Own
                work, CC BY-SA 4.0,
                https://commons.wikimedia.org/w/index.php?curid=58368724

    • Z shell (zsh) was written by Paul Falstad in 1990 while studying at Princeton University. It is named after then-Princeton professor Zhong Shao. In 2019, Zsh became the default shell in macOS.

      By Paul FalstadScreenshot:Vulphere — Self-taken;
                derivative work, MIT,
                https://commons.wikimedia.org/w/index.php?curid=79476954

Installing Linux:

Before trying to install Linux, get a full inventory of what your computer has. In the past, you might have had to help the installer recognize the hardware. Nowadays the installer takes care of most the configuration.

Boot from the USB drive and sit back. The only thing you would have to decide is if you want to format the whole drive or share it with another OS.

Depending on the distribution (distro), you might need to update your installation right away. If the distro is based on Debian and it has apt as in the case of Ubuntu and its derivatives like Linux Mint, you might want to run the following on the console as root (sudo -i).

          
          apt-get update &&
          apt-get upgrade -y &&
          apt-get autoclean -y &&
          apt-get autoremove -y &&
          apt-get purge -y &&
          reboot
        

I would recommend doing the latter on a daily basis.

Single-Board Computers:

Some vendors have started to offer single-board computer (SBC) units. For example, the Raspberry Pi Foundation released its Raspberry Pi 1 Model A in February of 2012. After several generations with a price tag under $50, several projects have used Raspberry Pi hardware.