MSDOS, UNIX, VMS, routers, and many other operating systems and devices have a command line interface (CLI), as opposed to a graphical user interface (GUI) like the Windows or Macintosh operating system.
You can do the same things with either type of interface, but a GUI is generally easier to learn than an equivalent CLI because you do not have to memorize the commands and their formats. On the other hand, with practice you may find it faster to work with a CLI, and it is easy to write small programs that execute several commands automatically.
Many operating systems offer both options, for example, there are several GUIs available for Linux, and Macintosh and Windows users can use command lines if they wish.
The command line interpreter in Windows is called command.com, and you can start it by entering command in the run (start > run) window:
That will open a command line window like the one below:
The command line interpreter has displayed the command prompt, ending in ">", and the blinking cursor ( _ ) indicates that it is waiting for me to type a command. As you see, the prompt shows the name and path to the current directory:
This is an abbreviation of the full path to the current directory, which is:C:\DOCUMEN~1\LARRY
C:\DOCUMENENTS AND SETTINGS\LARRY
The path is abbreviated because MSDOS file names can be no more than 8 characters long. (If you start the command line interpreter by opening a DOS windows under the accessories menu, you will see full path names).
At this point I typed in two commands:
The first, CD \, changed the current directory to the root of drive C, the hard drive on my computer.
The second command, CD temp, changed the current directory to the temp subdirectory.
This is a short illustration -- there are many MSDOS commands. A few of them are described in this short reference, and the best way to learn is to play around with them.