Command definition (in computing)

Before it existed Windows, the first MacOS or any other computing environment that is visually managed by using the mouse (or now playing with your fingers on the screen), computers were larger and rougher to interaction human, having to give orders through words written on the keyboard which could be followed by various parameters to modify their functioning.

In computing, a command is an instruction or command that is given to computers through a keyboard or analog device.

Interaction through commands presupposes the existence of a command interpreter, a program that receives the instructions that we are giving it in the form of a written command, and executes them.

At this point, it is best to give an example of what I am talking about.

Older operating systems without a graphical environment, such as MS-DOS (and its DR-DOS type variants or the current FreeDOS) interact with the user at the system level through a command interpreter and the corresponding commands that it is capable of to recognize.

Anyone who is old will remember the days of MS-DOS. Thus, for example, the command to see the list of files and folders contained in a binder it was DIR.

But let's complicate things a bit ...

The parameters they are modifiers of the action of the commands, or data necessary so that they can execute the entrusted task.

For example, in MS-DOS, to prepare a physical disk (like an old-fashioned floppy disk) we had to use the command FORMAT . But this one, simply put, would show us an error because it would need to know what Unit give Format. FORMAT A: would be an example of correct use of the FORMAT command, since we are indicating that it format the drive A:, and the latter would be the necessary parameter to carry out the action.

Confused? Let's give it one more twist ...

In any operating system the commands can be internal or external.

Earlier I explained that commands are processed by a shell. It may have been programmed to directly recognize various "keywords" and perform actions when it has recognized them. These are the internal commands, which do not need to be implemented separately, and which the interpreter recognizes directly.

External commands are nothing more than executable files that the interpreter will automatically search for one of the folders that it has marked as system folders.

In this sense, if we delete the file containing the command, we are left unable to use it.

Finally, a reflection: have you noticed that in almost all operating systems with graphical environments we have the option of opening something called Command line? Its use is normally restricted to professionals and amateurs who have a good understanding of the computer, but it is there for everyone who wants to dare. You just have to know... Some commands!

Fotolia photos: Gorodenkoff / Superingo

Topics in Command (in computer science)