Command-line programs such as ImageMagick or ffmpeg are important in the server world. CLIs are text-based interfaces, where the user types in the program name to execute, optionally followed by arguments.ĭespite the prevalence of GUIs, command-line programs still have an important role in today’s computing world. Not so long ago, before the advent of the GUI, command-line interfaces ( CLI) were the primary method for interacting with computers. GUIs, as the name implies, are based on the user visually interacting with the computer via input devices such as the mouse by selecting or operating on screen elements such as menus, buttons etc. The typical Mac user interacts with their computer using a Graphical User Interface ( GUI). Update 7/21/17: This command line programs on macOS tutorial has been updated for Xcode 9 and Swift 4.