Windows.XP.in.a.Nutshell.1002005.2Ed [Electronic resources] نسخه متنی

6.2. Command Prompt Choices

Windows XP provide
three different components, all essentially different implementations
of the command-line interface. These three components work similarly,
but there are some important differences and limitations.

Command Prompt (cmd.exe)

Commonly known as a DOS box because of its visual and functional
likeness to DOS, the Command Prompt window (see Figure 6-1) is the most complete implementation of the
command prompt in Windows XP. Any program, GUI or command-line-based,
can be started by typing its executable filename at the prompt. In
addition, a variety of internal DOS commands (discussed later in this
chapter), used primarily for file management, can be executed at the
prompt.

Figure 6-1. The Command Prompt window

If a command-line-based program is launched, it is run in the same
window. Many command-prompt applications simply display information
and quit; in this case, you'd be returned to the
prompt immediately after the program output.

An important distinction between the Command Prompt and the
alternatives below is that the Command Prompt maintains context
between commands. Each instance of the
command interpreter runs
in its own virtual machine, each with its own
"environment." The environment
includes such information as the current directory, the search path
(the directories in which the command interpreter looks for the
commands whose names you type), and the format of the prompt. Some
commands, once issued, change the environment for subsequent
commands. The most obvious example of this is when you type a
sequence of commands, like this:

C:>cd \stuff
C:\Stuff>notepad myfile.txt

This command sequence couldn't be carried out at
either the Run prompt or the Address Bar. Since they execute only one
command at a time and then exit, the context is lost between each
command. Concepts such as "change
directory" therefore have no meaning.

But the Command Prompt has limitations as well. Unlike the Address
Bar or Start Run, if you
type a web address (URL) or the name of a folder at the
Command Prompt, you'll get a "not
recognized" error.

Note that Windows XP also includes

Start
Run

Any program can be run by typing its
executable filename here, as shown in Figure 6-2,
just like in a Command Prompt window. However, in the case of
command-line based programs, the context is lost every time a new
program is launched. Internal Command Prompt commands, such as CD and
DIR, discussed later in this chapter, are not recognized here or in
the Address Bar.

Figure 6-2. The Start
Run dialog

Unlike the Command Prompt, you can type a web address (URL) here to
open it in the default web browser, or any folder name to open it in
an Explorer folder window.

Start Run is commonly
used to start programs, which is an alternative to wading through
Start Programs or opening
a new Command Prompt window. However, if you've
enabled the Address Bar, there's little need for
Start Run, since the
Toolbar is so much more convenient.

Address Bar

The Address Bar, shown in Figure 6-3, is nearly the functional equivalent of Start
Run, with a few
exceptions. There are actually three different Address Toolbars: the
one attached to the Taskbar, the one that's part of
Windows Explorer, and the one that's part of
Internet Explorer.

Figure 6-3. The Address Bar on the Taskbar

The Taskbar Address Bar can be enabled by
right-clicking on an empty area of the Taskbar and selecting Toolbars
Address. This
implementation is functionally identical to Start
Run.

The Address Bar can be enabled in
Windows
Explorer and Internet Explorer by going to View
Toolbars
Address Bar. In either of
these Windows, the launching programs is handled the same way as with
the Taskbar Address Bar and with Start
Run.

The various Address Bars differ only in the way folder names and web
addresses are handled. If you type a folder name into either Windows
Explorer or Internet Explorer, the contents of that folder will be
shown in the current window (i.e., no new window will be opened). If
a web address, such as http://www.annoyances.org/, is typed into the
Taskbar Address Bar or the Windows Explorer Address Bar, that address
is opened in the default web browser. If, the other hand, an address
is typed into Internet Explorer's Address Bar, the
page at that address is opened in IE regardless of the default
browser setting.

The main difference between the Address Bar and the Start
Run prompt is in the
assumptions that are made about ambiguous names and addresses. For
example, if you type Notepad or
http://www.annoyances.org/ into either place,
Windows would launch a program or web site, respectively. If you type
something that Windows won't recognize, though, like
BigBadaBoom, what happens next depends on where
the text was typed. If you type the text into an Address Bar, Windows
XP will open a web browser to the location

http://BigBadaBoom/ and then complain that the
web site doesn't exist. If you type the same text at
the Start Run prompt,
you'll get an error message explaining that
"Windows cannot find BigBadaBoom."