DOS lives! Secrets of the Windows command prompt

Computerworld - Buried deep within Windows' bosom is a carbon-crusted fossil from the ancient days of computing. This aged wart on Windows' soul harkens back to a more primitive time, when computers lacked the oomph to go graphical and mice were nothing but rodents.

I speak of the command prompt, whose roots lie in DOS, that antique operating system of the 1980s. DOS is gone now. Most old DOS programs lost Windows compatibility after the release of Windows 98, and Microsoft even held a mock funeral for the once-dominant PC operating system about a decade ago.

Yet despite Windows' glorious graphical goodness, a wispy memory of text-based computer life still exists. It's a program called CMD.EXE, and it appears in Windows as the command prompt window.

Believe it or not, the command prompt to this day still serves as a useful alternative way to control your computer. Indeed, there are some things you can do in the command prompt window that in Windows' graphical interface are tedious, slow or darn near impossible.

Come with me as we discover how an old warhorse like DOS can once again find purpose.

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Command prompt 101

Text commands, while obscure, are potent. Armed with the right commands and the know-how to use them, you can, even in 2007, fully control any Windows computer from your keyboard alone.

The command prompt window isn't really text mode, not like the old days. Rather, it emulates text mode.

In fact, over the years, Microsoft has continued to make the command prompt more and more powerful. Rumor has it that some Windows programmers at Microsoft almost exclusively use the command prompt to configure and run their systems. Given the richness and breadth of the text mode commands, it's easy to see why.

For now, let's begin by opening the command prompt window. Click the Windows Start menu, click All Programs, choose the Accessories submenu, choose Command Prompt, et voila, you should be looking at a standard command prompt window.

The command prompt window emulates the old full-screen text mode of yesteryear in a small window on your screen. Inside the window you should see 80 columns by 25 rows of text. A command prompt (which begins with C:\) indicates what directory you're currently in. And a blinking cursor shows you where to type your text. It's all cryptically simple.

What you type at that prompt are commands. Later on, we'll test drive a whole passel of commands, some as ancient as the first version of DOS back in 1981, some brand new with Windows Vista, but for now, just type

VER

and press Enter. You should see text telling you the current version of your operating system, similar to what's shown in Figure 1, below.

Figure 1. Typing VER at the command prompt tells you which version of Windows you're running.

Before digging further into the command prompt, here are a few things to keep in mind when working at the command prompt level:

• Commands can be typed in uppercase or lowercase. Traditionally, DOS commands are written in ALL CAPS, as we're doing in this story, but you don't have to type them that way.
• Anything you type is ignored until you press the Enter key. You can use the Backspace key to back up and erase. You can also use the left and right arrow keys to edit text.
• You can quickly summon a previous DOS command by pressing the up arrow key. Pressing the up arrow key repeatedly pages back through the past several commands you've typed at the prompt.
• The Cancel sequence in DOS is Ctrl+C.
• Yes, the error messages are cryptic and useless. Welcome to 1988!
• You can change the size and appearance of the command prompt window itself. For pointers, see the sidebar Working the window.
• To finish your DOS session, simply close the window. Or if you want to be completely texty about things, type EXIT to make the command prompt window go bye-bye, just like in the old days.