Command interfaces are interfaces where a user performs an action or a task by entering commands on the command line. The commands usually take the form of abbreviations where a combination of commands would require strict adherence to proper syntax. Some commands are also performed or called using a combination of keys such as the Shift, Alt, and Ctrl keys; through pressing of the function keys; or through pressing of keys such as the Delete, Esc, or Enter keys.
Command interfaces don’t usually contain graphical elements. It would involve only a black or grey screen, with a white- or black-colored font. The only elements that catch the user’s attention or that gives the user any hint as to where he or she is would be the command prompt and the blinking cursor.
After the user enters a command, the output or result of the command displays on the same screen, with the same font type, font, color, and font size, and with very little spacing in between.
Some users – particularly technical users such as developers and system administrators – favor command interfaces because this type of interface enables them to perform tasks with speed, precision, and efficiency. It enables them to run multiple commands through a one-step action.
However, this interface type seems to come with more issues than benefits. For one, it does a poor job of getting the user’s attention. If a newbie were presented with this type of interface without any prior knowledge or background about the interface then the user would be at a loss on where he or she should start to go about his or her task. With the absence of graphical elements on the interface, it would also be hard for the user to make sense of or perceive the information presented to him or her. Aside from having only the command prompt and the blinking cursor to start with, the single font color, font size, and font type, as well as the lack of spacing in between the lines of text, make it difficult for the user to discern or distinguish which output belongs to which command, especially when the user has already entered a lot of commands. In addition, since the commands are abbreviated, it would be hard for the user to understand what the command is for, especially if he or she is just a beginner. This also makes the commands and the output of these commands very hard to read.
Since the only way for users to perform tasks on a command interface is by manually typing the commands, the user is required to know and memorize all of these commands. The interface type provides very little, if any, means to help the user recall or recognize the appropriate command that he or she needs to run at any given time. As such, it would also make learning of the interface’s use quite difficult. It does not present the user with any visual cues that would enable him or her to easily remember or learn the different commands needed to perform the different tasks. To effectively learn the use of the interface type, the user must be able to memorize all of the commands, the proper syntax for using them, as well as the different parameters that can be used with them. The user must also constantly use these commands and the interface type to further aid in the user’s recall and to keep the user from forgetting them.
Rogers, Y., Sharp, H., & Preece, J. (2007). Chapter 6: Interfaces and interactions. In Interaction
design: Beyond human-computer interaction (2nd ed.) (216-288). Hoboken, NJ: John
Wiley & Sons