Lurking under Windows is the little-known world of the command line. We explain how to use this to fix faults and make your PC much more secure
In the days before Windows, firing up a PC would result in little more than a puzzling C:\> prompt followed by a blinking cursor. This was known as a command prompt (or, sometimes, Dos prompt) and in order to make the computer do anything, the user would have to type instructions from memory or a crib sheet.
Evidently, this method of operating a PC had limited attraction and few people would want to return to the dark days of the Dos prompt.
And yet, surprisingly, the command line is still available in all versions of Windows. Why? The reason is that typed instructions still provide a fast and powerful way of controlling many aspects of Windows, without all the annoying graphical paraphernalia.
As this article will show, it can be a very useful tool for fixing faults and checking, monitoring and even improving security.
Incidentally, we freely admit there is also a little bit of the ‘because it’s there’ spirit in this article: command-line instructions are free tools and, although they are not usually essential, learning the basics can also help to demystify some of the inner workings of Windows.
Before proceeding, two points of order. First, this article is not for novice or nervous PC users (though our instructions will be in plain English, as ever). Second, back up your PC: we cannot be held responsible for any problems that arise from your use of the command line.
The Windows Command Prompt
Before Windows appeared, an operating system called MS-Dos – short for Microsoft Disk Operating System – ruled the PC world. This provided the link between the user and the PC’s hardware and was text-based, requiring only a keyboard for operation.
Technically, MS-Dos uses what’s known as a command-line interface (CLI), while Windows employs a graphical user interface (GUI).
Versions of Windows before XP needed MS-Dos in order to work, because Windows itself could not access the PC’s Bios (essentially a bit of computer code stored in Rom chips inside the PC to get it working to the point where a proper operating system can take over).
Users could choose whether to launch Dos or Windows when the PC started, with most choosing Windows for obvious reasons.
Windows XP introduced a tool called Command Prompt, which exists still in both Vista and Windows 7. It looks a bit like MS-Dos but it’s really just an MS-Dos emulator running inside Windows.
Regardless of the technicalities, Command Prompt allows access to some lesser-known tools and settings. Because it dispenses with graphics, Command Prompt is very fast and, in some cases, it can be used to do tasks that are impossible in Windows.
Of course, there are downsides, not least of which is the mysterious nature of many commands. Microsoft publishes a complete list commands, how to use them and their various options (called switches or parameters). Click here for the Windows XP list and here for the Vista/7 version.
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