BATCH FILES

    Batch files are files with a .BAT
extension which have a special function with
DOS.  They contain one or more lines of text
which are the same as commands you can type
at the command line.  When you type the name
of a batch file at the command line, it's
lines are executed by DOS just as if you
typed them at the command line yourself.

   A simple use of a batch file is to replace
a long typing job at the command line with a
short one.  Let's say you want to start a
program called STARGAME.EXE which happens to
be in a sub-directory called
D:\GAMES\MYGAMES\STARGAME. Normally you would
have to type:

D:\GAMES\MYGAMES\STARGAME\STARGAME.EXE

    Instead, you can create a batch file
with any text editor or word processor which
works in standard ASCII text mode and call it
SG.BAT. SG.BAT can contain a single line of
text: D:\GAMES\MYGAMES\STARGAME\STARGAME.EXE.

Now, to start STARGAME all you have to do is
type SG.

   Going a step further, let's say that you
have to switch to the sub-directory
containing STARGAME before you can run it,
because the game itself needs to access files
in it's directory.  And, perhaps you are
logged to a different disk.  Normally you
would have to type three lines before you
could play the game:

D:
CD \GAMES\MYGAMES\STARGAME
STARGAME

If you wrap these three lines up in a batch
file called SG, then you'll only have to type
SG to start your game.

    Many programs come with their own batch
files to make your life easier.  Instead of
having to look over a long list of files
which come with the main program, you can
just look for a start-up batch file.  Common
batch file names are BEGIN.BAT, GO.BAT and
START.BAT.  Other likely names are the same
name as the program, or the initials of the
program, followed by .BAT.
    If you have a program which comes with a
start-up batch file, it is best to use it,
rather than running the program directly,
because start-up batch files may contain
auxiliary information which your program
needs to start properly.  For instance, it
may run differently depending on whether it
is installed on a hard disk or floppy disk.
The proper way to start will be contained in
the batch file.

    Batch files can run most DOS commands
including COPY, DIR, DEL, and CD, RD and MD.
    You can use combinations of these to
accomplish tasks you do often.
    It is common to use MD to create a
directory, then immediately switch to that
directory.  I've made myself a little batch
file called ZD.BAT.  It contains:

MD \%1
CD \%1

%1 represents a variable, it is whatever you
type on the command line after the batch file
name. In this case, it is a new directory
name. So, if I wanted a new directory called
\FROG, I could simply type:

ZD FROG

and my new directory will be created.
(Notice I don't even have to type the
backslash, since the batch file does that for
me.

    In addition to using the %1 variable,
there are 8 more, %2 through %9, each one
will pick up the next successive word,
filename or directory name you type at the
command line.  If you were to create a batch
file containing these lines:

COPY %1 A:
COPY %2 A:
COPY %3 A:

Then you could type the batch file name,
followed by three filenames (separated by
spaces) and they would all be copied to a
floppy disk in the A drive.

     There is also a %0, which refers to the
batch file itself.  You can use it for such
operations as making a self-deleting batch
file.  A batch file for installing a new
program is useful only once, so you can add
the line:

DEL %0

to the end of the batch file, and it will
disappear when it is done installing the
program.

    Echo is a DOS command which will show
whatever follows.  So a batch file containing
this line:

ECHO Hello there!

would display "Hello there!" when run.

In a batch file containing other commands,
your ECHO messages may not stay on the screen
for very long, so you can use another DOS
command called PAUSE, which will stop the
batch file until the user presses any key.

    There is a DOS command called TYPE which
will display up to a screenful of text at one
time from any standard ASCII file.  You can
use this in batch files to display important
information.  Example:

TYPE README.DOC

                AUTOEXEC.BAT

    There is a special batch file in the root
directory of your hard disk called
AUTOEXEC.BAT.  When the computer is turned
on, and DOS is loaded, it looks for this
batch file.  If found, it processes what it
finds in AUTOEXEC.BAT right away.  It is
common for computers with Microsoft Windows
installed to have an AUTOEXEC.BAT file
containing the line WIN, to automatically
start Windows everytime the computer is
turned on.

    These basics will help you get started
with batch files.  There is much more to
batch files, and whole books have been
written about batch language programming.
Special programs have also been written to
extend the powers of batch files into
processing math, asking for and processing
user input, and displaying graphics.

_____________________________________________
                              end of file.