UNIX

Firstly, what is an operating system (OS)?
An OS is the low-level software that acts as a resource manager, supports a computer’s basic functions and allows software to access system resources like processing, memory and storage. An operating system enables the computer to work.

What?

UNIX is an operating system first developed in the 1960s. It is a stable, multi-user, multi-tasking system for servers, desktops and laptops.

UNIX systems often have a graphical user interface (GUI), a visual prompt which you can interact with and pass commands via clicking and typing, similar to Microsoft Windows; when you boot the machine, this is what you’re seeing. Not all operations are included in a GUI but can be accessed via the systems command line interface.

UNIX-like OS

There are many different versions of UNIX, although they share a common foundation. The most popular variations of UNIX are Linux and MacOS.

Linux is an incredibly popular OS to run on a server, for automation and hosting an application or service. It can be light-weight and flexible, often avoiding the problems of bloatware and pre-installed software.

Inside UNIX

A UNIX operating system is made up of three parts: the kernel, shell and applications.

The kernel

A system’s kernel is the core of the operating system; it handles the file-system, system calls and received commands, memory allocations and processing time for applications.

The shell

The shell is a command line interpreter (CLI) which acts as an interface between the user and the kernel. After processing a command, the shell returns a prompt allowing for more commands. Typically commands are handled serially (one at a time) but can be performed concurrently, likely in parallel (multiple commands running at the same time).

Bash

Bash is the default UNIX shell for most Linux distributions and MacOS, up to Catalina, it has since been replaced on MacOS with zsh.

The Bash language was written by Brian Fox for the GNU Project and was first released in 1989.

The Terminal

Mac and Linux OS have a terminal (Command Prompt in Windows), it is a text input / output environment that sits on top of a shell. The shell receives the commands, interprets them, processes and returns any output back to the terminal. This is a human - machine interface.

git BASH for windows

git BASH is a BASH emulator which will allow us to work in similar ways to UNIX-like, Linux and MacOS machines. Our aim is to work with similar patterns and tooling, to work in the same way across different operating systems. When installing git no a Windows machine, git BASH should come bundled with it.

Typically when putting code into production, this is done on servers which have a UNIX-like operating system and use BASH. Experienced developers also natively work on machines running a UNIX-like OS such as Linux or Ubuntu - for these reasons it’s a good idea to work with similar tooling where everyone can run each other’s code. Read about git BASH here.