Command Line Interface

A command-line interface (CLI) is an interface between the user and a program. GUI was not supported by early operating system and text-based commands were used for communication between user and the computer.

CLI system does not have mouse as an input device and generally keyboard is used for input where the messages are sent by typing a command and then by pressing the enter(return) key. After a command is processed, a new prompt is issued for accepting next instruction from the user.

CLI definition
Command line interface is an interface between user and computer where a line of text (called command line) is passed between the two for communication.

Above image represents cmd.exe which provides command-line interface in Microsoft Windows OS. Unix and Linux has a command interpreter called Shell for CLI.

CLI operating systems are not used(or less used) now as GUI operating systems have gained popularity for it’s user friendly environment. In a GUI operating system, the user responds to graphic images and controls like buttons, text-box, radio-button etc. on the screen instead of typing in commands in response to a prompt.