Command-line Interface

A command-line interface or command language interpreter (CLI), is a means of interacting with a computer program where the user (or client) issues commands to the program in the form of successive lines of text (command lines) - wikipedia

The CLI was the primary means of interaction with most computer systems until the introduction of the video display terminal in the mid-1960s, and continued to be used throughout the 1970s and 1980s on OpenVMS, Unix systems and personal computer systems including MS-DOS, CP/M and Apple DOS. The interface is usually implemented with a command line shell, which is a program that accepts commands as text input and converts commands to appropriate operating system functions.

The command-line interface evolved from a form of dialog once conducted by humans over teleprinter (TTY) machines, in which human operators remotely exchanged information, usually one line of text at a time - wikipedia

Early computer systems often used teleprinter machines as the means of interaction with a human operator. The computer became one end of the human-to-human teleprinter model. So instead of a human communicating with another human over a teleprinter, a human communicated with a computer.