time. Instead, you must look at each subdirectory to see
what is in that one. If E5 Christmas wants to see what
files are in the subdirectory SUPPLY, she would use the
DOS command to change the directory name to
SUPPLY and then display its directory (figure 2-18,
example A).
As the number of files on a disk increases, so does
the need to have a disk that is well-organized. A well-
organized disk can save you a considerable amount of
time and frustration in locating files. As computer
specialists, we know this is true and of great importance,
but to the uninformed or new user who has not been
properly trained, disk management may seem very
cumbersome and time consuming. Some users may not
even be aware that they can organize their files on disk,
and that’s where you come in. How can you help users
create and use a tree-structured directory? you might
ask.
Whenever you format a disk, a single directory
called a root directory is created. You can then instruct
DOS to create or MaKe other DIRectories, using a
command such as MKDIR or just plain MD. These are
called subdirectories. Further, a subdirectory can have
other subdirectories. Directories, regardless of their
level, are given names just like any other files. DOS
keeps track of each directory the same way it does your
files. Using various DOS file handling commands, you
can create (MKDIR or MD), change (CHDIR or CD),
and remove (RMDIR or RD) directories and
subdirectories. To move through the tree structure (UP
or DOWN), you must issue commands that use a
path name. A path name is a list of the directory(ies)
(which might end with a file name)
that DOS
Figure 2-18.—Examp1es of files in subdirectories.
2-28
must follow to find a given directory/subdirectory or
file name. In example B in figure 2-18, to locate the
file named DIN-MENU.DLY, the path is
\CHRISTMAS\FOODSERV\DIN-MENU.DLY.
Once you have grouped related files into a
subdirectory, you can act on them as a unit. The DOS
file-handling commands can be applied to an entire
subdirectory of files in a single stroke. For example, you
can issue commands to copy, print, or delete all the files
in a subdirectory as easily as you can for a single file.
Other files on the same disk, but in different directories
go unused and undisturbed. Subdirectories are
especially helpful when working with hard disks
because of their large storage capacities.
To learn more about DOS directory structures and
commands, read the DOS reference guide that
accompanies the DOS software.
Backing Up Files
You have heard it before, and you are going to hear
it again here: BACKUP your programs and data files.
If you don’t, you will eventually lose all or part of your
data, and the only person you can blame is yourself.
Data can be lost or damaged in a number of ways.
Common causes of data loss are power surges and
drops, power failures, and user errors. User errors top
the list. Less common but potentially disastrous are fire,
theft, vandalism, and natural disasters.
How often have you come close to erasing a file or
formatting a floppy or hard disk by accident? Probably
more times than you care to admit. No matter how many
precautions you take, you can’t prevent all the potential
ways data can be lost. You can certainly reduce their
adverse effects by backing up your files on a regular
basis.
When working with data files, you will want to back
them up at least on a daily basis either to tape, diskette,
or to another hard disk. For our example, we will use
two diskettes. A technique referred to as the odd/even
backup uses two diskettes. Label one diskette as odd
and the other as even. When you make your backups,
use the odd diskette on odd days, and use the even
diskette on even days. This pays off when you find that
errors were inadvertently made to a file the day before,
and you backed-up that file onto your backup diskette.
With this system, you can go back 2 days if needed.
No matter how many backups you make (two,
three, or one for everyday of the week) or what method
you use to make them, they are worthless if they are
