Introduction

Today, with the widespread use of computing devices, graphical user interfaces (GUIs) are all-pervasive and easily learned by almost anyone. However, we should not ignore one of the most powerful tools from a bygone era, which is the command-line interface (CLI).

GUIs and CLIs approach user interaction from different angles. While GUIs emphasize user-friendliness, instant feedback, and visual aesthetics, CLIs target automation and repeatability of tasks, and composition of complicated task workflows that can be executed in one shot. These features result in the command line having widespread utility even today, nearly half a century since its invention. For instance, it is useful for web administrators to administer a web server via a shell command-line interface: instead of running a local CLI on your machine, you remotely control one that is running thousands of miles away, as if it were right in front of you. Similarly, it is useful for developers who create the backends of websites. This role requires them to learn how to use a command line, since they often need to replicate the web server environment on their local machine for development.

Even outside the purely tech-oriented professions, almost everyone works with computers, and automation is a very helpful tool that can save a lot of time and drudgery. The CLI is specifically built to help automate things. Consider the task of a graphic designer, who downloads a hundred images from a website and resizes all of them into a standard size and creates thumbnails; a personnel manager, who takes 20 spreadsheet files with personnel data and converts all names to upper case, checking for duplicates; or a web content creator, who quickly replaces a person's name with another across an entire website's content.

Using a GUI for these tasks would usually be tedious, considering that these tasks may need to be performed on a regular basis. Hence, rather than repeating these manually using specific applications, such as a download manager, photo editor, spreadsheet, and so on, or getting a custom application written, the professional in each case can use the command line to automate these jobs, consequently reducing drudgery, avoiding errors, and freeing the person to engage in the more important aspects of their job. Besides this, every new version of a GUI invalidates a lot of what you learned earlier. Menus change, toolbars look different, things move around, and features get removed or changed. It is often a re-learning exercise filled with frustration. On the other hand, much of what we learn about the command line is almost 100% compatible with the command line of 30 years ago, and will remain so for the foreseeable future. Rarely is a feature added that will invalidate what was valid before.

Everyone should use the command line because it can make life so much easier, but there is an aura of mystery surrounding the command line. Popular depictions of command-line users are stereotypical asocial geniuses. This skewed perception makes people feel it is very arcane, complex, and difficult to learn—as if it were magic and out of the reach of mere mortals. However, just like any other thing in the world, it can be learned incrementally step-by-step, and unlike learning GUI programs, which have no connection to one another, each concept or tool you learn in the command line adds up.