|
ALS 3203 - Lesson 2,
Recognizing Program Files
Computer Programs run from executable files. These
files may be recognizable by their filename extensions (the 3 letters after the
dot).This is not true for Macintosh systems, as compter programs are recognized by header information and filename structure differs from IBM PC filenames.
MACINTOSH users: your directory structure differs from PC. Drives are indicated by a letter followed by a colon, so the equivalent of dive C:\ on a PC might be C: on your system.
Three of the more common Executable filename extensions include:
In the distant (computer life) past programs were run by typing the file name
of their executable file at a command line prompt, usually C:\>. For example,
to run WordPerfect (DOS version) one would type WP at the command line prompt
and WordPerfect would load. This is because one of the files on your
PC computer, autoexec.bat, contains a line named PATH, which lists all of the
locations your computer looks when a file is selected. If the filename is a program,
and the locations in PATH contain the location of this file, the program will
execute.
With the advent of Windows and the GUI (Graphical User Interface) we moved to
selecting icons with the mouse to run programs. What lies hidden behind all of this is
when you click on a program icon it's executable file is run in the background,
you just don't have to type the filename (it's done behind the interface).
Windows still has a command-line capability (as you have found out), although is is harder to find and
use. The most obvious way is to exit from within the Windows desktop (Start,
Programs, MSDOS prompt or Command prompt.) In Windows 2000 or later you may
have to search for the Command Prompt program. In earlier versions you may
use the Start, Run box to load command. In Windows XP, you may not even be able
to easily access a command line.It may be found under accessories, Command, or you may use a Command prompt icon such as the one here, or type "command" or "cmd" (without the qutoes)
in the Start, Run, box.
You now know that If you succeed in getting to command, you will be in a DOS
window at the command-line, with a prompt of C:\windows> or some other prompt, depending
on the default location of your application. To get to the root directory,
C:\>, just type cd\ (that's cd backslash) and press
enter. Your prompt should now be C:\>. You are now at the ROOT of your hard
disk. At any time you wish to get out of the comman line window, type "exit"" at
any DOS prompt and press Enter. You will be back in Windows!
But there is a more subtle way to do command-line
procedure from within Windows using the Start, Run option. Look closely at the
Run (from Start, Run) statements above the box. It says:
"Type the name of a program, folder, document,
or
Internet Resource, and Windows will open it for you."
Now try this. Don't leave these web pages but choose Start, Run (from your
desktop taskbar), then type in Explorer in the box
and choose ok. What happens?
Repeat this, entering Notepad, and then Wordpad
in the Start, Run box. Are you beginning to see?
The reason programs run is because you are typing the executable file
name and the computer is finding it and executing it. Now you know two ways
to use command-lines from Windows. Later on in the semester we will return to
this. For the moment this is sufficient introduction to the power of
command-line procedures.
Today is:
|
