What Is A Command-Line Interface?

Date First Published: 26th June 2023

Topic: Computer Systems

Subtopic: Computer Software

Article Type: Computer Terms & Definitions

Difficulty Level: 5/10

Learn about what a command-line interface is in this article.

A command-line interface (CLI), also known as a console-user interface, is a type of user interface based on text commands and a simple text-only interface. To navigate, open, move, rename, and delete files, users need to enter commands as inputs. An example of a CLI is Command Prompt in the Windows operating system or Terminal on a Mac.

Command-line interfaces are not used as much now and graphical-user interfaces are usually the default option for operating systems, software programs, and applications, but they are still used by experienced users who know the different commands and want to troubleshoot. System administrators often use them when managing hundreds or thousands of systems to easily adjust configurations for a large group of systems at once.

How Does A CLI Work?

A CLI works by taking and processing text-based commands from users. Afterwards, the output is displayed on the screen, like whether the command was successful or failed. Users need to quickly enter their single-line command to make the most of their applications.

Although every CLI uses its own syntax, they all function in a very similar way. For example, every CLI has a command prompt, which is shown when the interface is ready to accept commands. When typing a command, the output always displays on the screen and when pressing Enter, the command is run. The CLI also provides feedback to the user, including error and success messages.

Advantages and Disadvantages Of A CLI

• Experienced users who know the different commands can perform tasks more quickly and efficiently than navigating around a GUI.
• Since the user interface is simple, it does not require much processing power and memory to run. This means that it can run on older systems that have limited memory and processing power.
• A CLI is supported by all operating systems. Unlike a GUI, no specific operating systems are required to run a CLI.
• Scripts can often be stored to automate regular tasks across multiple computers, which cannot usually be done in a GUI.

• Users need to know the different commands to perform tasks. This makes it very difficult and confusing for inexperienced users to use and understand.
• The interface is not intuitive at all. Users cannot figure out what to do just by giving it a go and some training is required to even make basic use of it.
• Commands have to be typed precisely and there is no room for any errors. Mistyping a command, even by a single letter, will result in users losing all of their progress and having to start from the beginning. It could also result in users performing the wrong action, like deleting the wrong file or transferring a file to the wrong location.
• Most commands are irreversible. This means that after pressing Enter, there is usually no way to pause or undo the command, so users have to make sure they don't enter any commands they don't intend to.

History

The origins of a CLI can go back to the 1960s. In the early days of computing, a CLI was the standard way of interacting with a computer. At that time, computers only had keyboards for input and the screens could only display text as output. Whilst GUIs are in more common use now, most operating systems still offer both interfaces to users and some programming and maintenance tasks may not have a GUI.

During the 1980s and 1990s, the introduction of the Apple Macintosh and the Microsoft Windows operating systems led to the CLI as the standard user interface replaced by the GUI. The command line remained available as an alternative user interface, often used by system administrators and other advanced users for system administration, computer programming and batch processing.

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