A batch file contains a series of commands that DOS executes
sequentially whenever you enter the name of the batch file and
press Enter at the DOS prompt. The batch file name must contain
the extension .BAT to execute. However, when running a batch
file, you do not enter the .BAT extension as part of the command
file name.
The batch file is saved as a DOS text file (in ASCII
format). It can contain DOS commands and/or special batch file
commands that are used only in batch files.
Batch files are frequently used to automate the execution of
a group of commands that you find yourself having to enter
manually over and over. These can include typical start-up,
maintenance, and backup procedures as well as such simple tasks
as renaming specific DOS commands to make them easier to remember
and access (such as FORMAT A: to PREPARE).
Each command statement in the batch file is listed by line
in the file, and DOS executes each statement in the order in
which it is entered in the batch file. DOS will terminate the
batch file as soon as it has executed the last command statement
in the file. To terminate a batch file at any time before this,
issue the BREAK command (either by pressing Ctrl-C or Ctrl-
Break). When you issue the BREAK command during the execution of
a batch file, DOS displays the message
Terminate batch job (Y/N)?
To have DOS to ignore the current command statement and
execute the next command statement, thereby continuing the
running of the rest of the batch file, type N. To terminate the
execution of the current and all remaining command statements
(that is, abort the batch file), type Y. (Note that some versions
of DOS require that you press Enter after typing Y or N. Also,
some commands that can be entered in a batch file will not
respond to the BREAK command.)
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
AUTOEXEC.BAT File
Chaining of Batch Files
COMMAND Command
Conditional Processing
Creation of Batch Files
DATE Command
Displaying of Text with Batch Files
ECHO batch file command
Loops in Batch Files
PRINT Command
Replaceable Parameters in Batch Files
Subroutines for Batch Files
Creation of Batch Files
You can create a batch file using the COPY command, EDLIN
(the line editor supplied with DOS), or any other editor or word
processor that can save its text in ASCII format. When creating
or saving the batch file, be sure to append the extension .BAT to
the file name you assign to it.
To create a batch file using the COPY command, use
the paradigm
COPY CON filename.BAT
where
filename Specifies the name you wish to assign to the
batch file.
After entering this, you simply type in each command
statement in the order you wish it to be processed when the batch
file is executed. After typing in each command statement, you
terminate the line by pressing the Enter key.
Once you have entered all of the command statements you wish
to have in your batch file, you save it on disk (in the current
directory) by pressing Ctrl-Z (you can also accomplish this by
pressing F6 on IBM PCs and most compatibles) and the Enter key.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
A)AUTOEXEC.BAT File
You can create a special batch file, named AUTOEXEC.BAT,
which contains all of the DOS commands that you wish to have
invoked every time you start your computer. The command
statements in the AUTOEXEC.BAT file often include such DOS
commands as DATE, TIME, PROMPT, PATH, and SET. These can also
include commands that execute special RAM-resident programs such
as Lightning or SideKick or a menu program of your own design.
Such a program would allow you to start up specific application
programs available on your PC- -dBASE III PLUS, Lotus 1-2-3, or
WordPerfect, for example.
Every time you start your computer, DOS checks for the
presence of the AUTOEXEC.BAT file on either the disk in drive A
if you are using a two-floppy disk system, or in the root
directory of drive C if you are using a hard disk system. If DOS
locates such a file, it automatically executes the statements it
contains upon completion of the boot sequence.
When you create the AUTOEXEC.BAT file, remember to include
the DATE and TIME commands along with the other commands you wish
executed each time you start the computer. (If your computer is
equipped with a clock/calendar card, enter the appropriate
commands to have the date and time read.) If you do not add
these commands, DOS will no longer prompt you for the current
date and time as part of the start-up procedure and, as a result,
the files you create with your application programs will not be
stamped with the correct date and time.
Consider the following example created with the COPY command
and containing a sampling of DOS commands typically used in the
AUTOEXEC.BAT file:
COPY CON AUTOEXEC.BAT
DATE
TIME
PROMPT $p$g
PATH = C:\;C:\DOS;C:\BATCH
(Ctrl-Z)
After creating this AUTOEXEC.BAT file, when you start your
computer DOS will first prompt you to update the date and time.
Once you have responded to these commands, DOS changes the prompt
so that it always displays the current directory, and then sets
the path so that it will check the root, \DOS, and \BAT
directories for any command that you enter, regardless of which
directory you are in at the time.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
PATH Command
PRINT Command
SET Command
A)Displaying of Text with Batch Files
The batch files that you create can contain messages that
are displayed to alert the user to the underlying purpose of the
batch file or to prompt the user to take a particular step- -such
as changing data disks- -during a pause in the execution of a
command. You can also add messages that are displayed as part of
the ECHO command, which controls whether the command statements
entered in the batch file are displayed to the user as they are
executed by DOS.
REM Command
One way to have text displayed on the screen during the
execution of a batch command is with the use of the REM (remark)
command
REM remark
where
remark Specifies the comment to be added to a
batch file.
DOS will not try to execute a REM command, although it will
display REM and the text that follows it on the screen unless it
has previously executed an ECHO OFF statement (see Using the ECHO
Command, which follows).
You can use the REM command to add messages to the batch
file that help make clear its function and procedure. If you wish
to add a nonprinting comment whose purpose is to document the use
of particular commands in your batch file but that is never to be
displayed on the screen to the user, you simply preface the text
of this type of comment with a colon, as in:
:Start backup
Comments prefaced with a colon will appear when you use the TYPE
command to display the contents of the batch file on your screen,
or when you use the COPY or PRINT command to obtain a printout.
PAUSE
You can also have messages displayed on the screen during a
pause in the execution of batch file commands. The syntax for the
PAUSE command is
PAUSE [message]
where
[message] Specifies the message you want to have
displayed on the screen when PAUSE is
invoked.
When DOS encounters a PAUSE statement, it pauses the
execution of the commands in the batch file and displays your
message on the screen, followed by its own message
Strike a key when ready. . .
on the line below. If you enter the PAUSE command without any
message text, you will see only this DOS message instructing you
to strike a key to continue the execution of the batch file.
When you use the PAUSE command, the word PAUSE is always
displayed on the screen along with the message you have entered
(just as when using the REM command). If the batch file has
executed an ECHO OFF command before it encounters your PAUSE
command, neither the word PAUSE nor the text of your message will
be displayed on the screen. Only the DOS message about striking a
key to continue will be visible (see Using the ECHO batch file command,
which follows).
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
PRINT Command
TYPE Command
A)ECHO
When DOS executes the commands in a batch file, it can
display each command statement on the screen as it is executed.
You can enter the ECHO command in the batch file to control
whether the command statements are displayed. The syntax is
ECHO [OFF]
or
ECHO [ON]
where
OFF Suppresses the display of command
statements during the execution.
ON Used if you wish to have subsequent
commands displayed on the screen during
the execution of the batch file.
Note that if you enter the ECHO command in a batch file (or
at the DOS prompt) without using either the ON or OFF parameters,
DOS responds by displaying the current state of the ECHO command.
You will see either ECHO is on or ECHO is off.
If you are using DOS 3.3, you can also suppress the display
of a command statement in the batch file by prefacing it with the
@ symbol. For example, entering
@VERIFY ON
will prevent the VERIFY ON command from being displayed. However,
each command statement that you wish to suppress must be prefaced
by an @ symbol. If you use @ECHO OFF, the ECHO OFF command as
well as all subsequent statements are automatically suppressed
until an ECHO ON command occurs.
When ECHO is off, only the display of the command statements
in the batch file will be suppressed. DOS will continue to
display any message that is normally shown after a particular
commandhas been processed. For instance, if your batch file
contains the statement
ECHO OFF
followed by a command to copy a particular file from one
directory to another, you will still see the DOS message
1 File(s) copied
although you will not see the contents of the COPY command itself
on the line above it. Note that you can often get rid of these
messages by redirecting output to NUL:
COPY *.* A: NUL
You can use the ECHO command to display messages to the
user. First, set ECHO to off. Then, enter an ECHO command
followed by at least one space and the text of your message. When
you use the ECHO command in this way, only your message is
displayed onthe screen. DOS does not include the command word
(ECHO) as it does when displaying messages with the REM or PAUSE
commands.
For example, you could have your batch file display a prompt
to insert a data disk in drive A by using the ECHO and PAUSE
commands as follows:
ECHO OFF
.
.
.
ECHO Insert data disk in drive A
PAUSE
When the batch file executes these last two commands, you see
only
Insert data disk in drive A
Strike a key when ready. . .
on the screen. ECHO does not appear along with the prompt
message, but the separate PAUSE command causes the Strike a key
when ready. . . message to be displayed.
When you use the ECHO command to display messages and
prompts, be sure that it is preceded by an ECHO OFF statement (or
an @ symbol if you are using DOS 3.3) in the batch file.
Otherwise, you will see the ECHO command statement containing the
message as well as the message itself when the batch file is run.
Note that the use of the REM, PAUSE, and ECHO commands to
display on-screen messages slows down the execution of the batch
file appreciably. If you need to include extensive instructions
for a particular batch file, use the TYPE command to have them
displayed on the screen.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
COPY Command
A)Replaceable Parameters in Batch Files
You can define parameters (or arguments) that are passed to
particular command statements in a batch file with the use of
replaceable or dummy parameters. This makes the batch file more
flexible because you get to define the arguments to be passed to
the command statements at the time you execute the batch file.
You can define up to ten different replaceable parameters to
be used in a batch file. Each one is given a number between 0 and
9 preceded by the percent sign, as in %1, %2, and so on. Note,
however, that the replaceable parameter %0 represents a special
case: it is always replaced with the file name of the batch file.
The other nine replaceable parameters have no such fixed
replacements: you can make then stand for DOS commands, file
names, parts of file names (such as extensions), directory paths,
and the like. For instance, you could use replaceable parameters
to create a batch file named WHEREIS.BAT that locates a
particular file for you. This batch file contains only a single
command statement using the replaceable argument, as follows:
CHKDSK /V | FIND ``%1''
The CHKDSK command with the /V parameter lists all of the files
and subdirectories for the current directory and pipes this
information to the FIND command.
The FIND command contains the replaceable parameter %1. When
you execute the WHEREIS.BAT file, you enter the filename you wish
to locate along with the batch file name. To locatea file called
LOAN.FRM on the hard disk, you run the batch fileby entering
WHEREIS LOAN.FRM
DOS will then execute WHEREIS.BAT as though you had entered
CHKDSK /V|FIND ``LOAN.FRM''
as the command statement. If this file is located in C:\WP\FORMS,
DOS will respond by displaying
C:\WP\FORMS\LOAN.FRM
As you can see, you can use this same batch file to search for
any file or group of files, simply by entering a different file
name at the time you execute it.
In complex batch files, you may find that ten replaceable
parameters are not sufficient. In such a case, you can use the
SHIFT command. SHIFT discards each argument after it has been
acted upon, replacing it with the next argument so that after the
first argument is processed, the second becomes the first, the
third the second, and so on. After you use the SHIFT command, the
0% argument is never acted upon, since the %n argument becomes
the %(n--1) argument. Note that SHIFT is useful in loops, which
are described later in this appendix.
Passing Arguments from the Environment
As noted in the SET reference entry, you can specify a set
of strings that the batch files can refer to. For example, if you
enter the SET command
SET REPORT = YREND
and have previously entered the following command line in a batch
file
COPY %REPORT%.WK1 A:
the batch file will copy the file named YREND.WK1 to the floppy
disk in drive A when the batch file is run.
Note that the replaceable argument in the batch file command
line is enclosed in a pair of percent signs (%). This indicates
to DOS that the argument is to be taken from the environment.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
COPY Command
FIND Command
A)Loops in Batch Files
There are several methods for creating loops in batch files.
If you want the entire batch file to repeat, you can use the %0
replaceable parameter as the last command. You will recall that
%0 is always replaced with the file name of the batch file. When
you add it asthe last statement in a batch file, it causes all of
the commands in thefile to be repeated. For example, if you
create a batch file namedDIRA.BAT that contains the command
statements
ECHO OFF
ECHO Insert new disk in drive A
PAUSE
DIR A:/p
%0
the file will repeatedly prompt you to insert a different disk in
drive A and then give you a directory listing of all of the files
it contains when you press a key to continue. This batch file
will continue to repeat until you press Ctrl-C or Ctrl-Break to
terminate it.
The FOR Loop
To repeat a command within a batch file for a specific
number of cases, you use the FOR command. The syntax for the FOR
command is
FOR %%variable IN (set) DO command
where
command Specifies the command to be executed for
each member listed in the (set)
argument, in the order in which these
members are entered. The command
argument can consist of only a single
command, which can be another batch file
command (except for the FOR command), an
executable program, batch file, or DOS
command. Note that you cannot nest FOR
batch commands, which is why the command
argument cannot contain another FOR
command statement.
set Specifies files to be operated upon.
variable Specifies the variable to be operated on
by the command. Notice that a double
percent sign is entered before the
variable (usually, though not
necessarily, a single letter) to
distinguish it from a replaceable
parameter.
Consider this example using the FOR command:
FOR %%A IN (1985.WK1 1986.WK1 1987.WK1)
DO COPY %%A %2
In this batch file, the FOR command statement copies each of the
three worksheet files listed in the (set) argument to the
directory path entered when the batch file is run by passing it
to the %2 replaceable parameter. Notice that the command argument
in this example is actually COPY %%A, instead of just COPY.
The GOTO Command
You can also cause a batch file to execute (and sometimes
repeat) a group of command statements in the file beginning at a
specific point. To do this, you use the GOTO batch command. You
indicate where in the batch file the commands are to be executed
(or repeated) by using a label.
The syntax of the GOTO command is
GOTO [:]label
where
label Specifies a character string of up to
eight alphanumeric characters, and is
not case-sensitive. By convention,
alphabetic characters are entered in
lowercase and the label name is prefaced
by a colon. Note that the colon is
mandatory before the actual label, but
optional before the argument in the
GOTO. The label, however, cannot contain
a period (.).
When you use the GOTO command, DOS executes all of the
command statements listed below the label until it reaches the
end of the batch file or another GOTO statement telling it to
begin reprocessing the commands or to process a new set of
commands beneath another label.
Looping with the GOTO command can be illustrated by the
following generalized form:
:label
command%1
.
.
.
command%n
SHIFT
GOTO :label
Assuming that the commands listed below the :label contain
replaceable parameters, with the use of the SHIFT batch command,
this loop would be executed indefinitely (until you terminated
the batch file by pressing Ctrl-C or Ctrl-Break).
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
A)Conditional Processing
The endless loop illustrated above is of limited use in
batch files. It is much more common to use the GOTO command with
conditional statements. That way, the commmands listed beneath
the label are executed only when the condition is true. Using the
GOTO command with conditions allows you to create batch files
that branch according to the result of the condition.
In addition to using conditional processing to branch, you
can also have command statements executed only when there is
equivalency between two items or if a particular file exists.
The IF Command
The batch IF command is used to allow conditional execution
of command statements. The syntax of the IF command is as
follows:
IF [NOT] condition command
If you wish to have branching occur as a result of the outcome of
the condition, use this form:
IF [NOT] condition GOTO [:]label
There is no ELSE command in the batch file command
vocabulary. If you wish to have the program branch to one set of
commands if the condition is true and another if it is false, use
this form:
IF condition GOTO [:]labela
GOTO [:]labelb
If the condition is true, execution jumps to the commands beneath
label a. If it is false, it jumps to those beneath label b. Note
that you do not have to use the second GOTO statement if the
commands to be executed when the condition is false follow the IF
statement directly.
Testing for Equivalence
The condition argument in an IF command can test for
equivalence between two items. If they are found to be equivalent
(that is, identical in terms of characters and case), then the
command statement listed in the command argument is executed.
When you test for equivalence, you use a double equal sign. The
syntax is as follows:
IF string1==string2 command
Note that strings are case-sensitive.
For example, you could enter the following IF command:
IF %1==December GOTO :endofyr
If you execute this batch file and enter December as the first
replaceable parameter, the batch file will jump to the label
:endofyr and execute the commands that are listed beneath it.
Testing for the Existence of a File
You test for the existence of a particular file as the
condition argument of the IF command. The syntax for this use is
as follows:
IF EXIST [d:][path]filename command
The options are as follows:
command Specifies a command to be executed
only when the file entered for the
d:path filename argument is found
on the drive/directory indicated
(if these parameters are omitted,
then in the current directory).
d:pathfilename Specifies the file to be operated
on.
For example, you might have this IF command statement in a
batch file:
IF EXIST 4QTRTOTL GOTO :yrend
The commands beneath the :yrend label are executed only if DOS
locates the file named 4QTRTOTL in the current directory. If this
file is not found, this GOTO statement is ignored.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
A)Chaining of Batch Files
You can chain batch files by adding the name of the second
batch file to be executed as the last statement in the command
statements of the first batch file. Do not confuse chaining batch
files with calling a new batch file as a subroutine. When
chaining batch files, control does not return to the first batch
file as when using subroutines (see the section on Using
Subroutines, which follows). Because of this, reference to the
second batch file must be entered as the last command statement
in the first batch file. If it is not, the commands below this
reference in the first file will never be executed.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Subroutines for Batch Files
A)Subroutines for Batch Files
To execute a second batch file as a subroutine (that is,
have control returned to the first batch file upon execution of
all command statements in the second file), you must load a
second copy of the command processor, using the COMMAND command.
The syntax is
COMMAND /C batch
where
/C Tells DOS that this a secondary copy of
the command processor.
batch Specifies the batch file you wish to
call as a subroutine.
To have control return to the first batch file and to have
the secondary copy of the command processor unloaded, the EXIT
command must be the last statement in the batch file used as a
subroutine. If you do not place EXIT as the last command
statement in the called batch file, control will not return to
the calling batch file and the secondary copy of the command
processor will continue to run.
Using The CALL Command
DOS 3.3 has added a CALL command that allows you to call a
second batch file as a subroutine (that is, execute the commands
in a second batch file without terminating the first batch file).
This command can be used in place of the COMMAND and EXIT
commands.
The syntax of the CALL command is
CALL [d:][path]filename
where
d:pathfilename Specifies the name of the
batch file to be called. When
entering this file name, do
not include the .BAT file
extension.
You can use the CALL command to call its own batch file.
However, you need to provide a method whereby the batch file is
eventually terminated.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
COMMAND Command
A)CONFIG.SYS File
Each time you boot up your computer, DOS searches the root
directory of the drive from which it was started for a file named
CONFIG.SYS. If this file is located, DOS executes all of the
commands it contains much like a batch file (although this file
is executed long before an AUTOEXEC.BAT file), according to the
values assigned by special configuration commands. If DOS does
not find this file in the root directory, it supplies its own
default values for all of the configuration commands it requires.
The CONFIG.SYS file is used, then, only when you need to set
new values for particular configuration commands. The parameters
that can be modified in the CONFIG.SYS file include:
þ The BREAK status
þ The number of disk BUFFERS
þ The COUNTRY specification
þ Additional DEVICE drivers
þ The maximum number of drives that you may access
(LASTDRIVE)
þ The maximum number of files that can be open
concurrently by file handlers (FILES)
þ The maximum number of files that can be open
concurrently by file control blocks (FCBS)
þ The SHELL
þ Override the default stack resources (STACKS)
Each of these parameters is explained in this appendix, along
with its associated commands.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Creation of CONFIG.SYS File
BREAK Status
BUFFERS Parameter
COUNTRY Parameter
DATE Command
Devices, Drivers for
LASTDRIVE Parameter
FCBS Parameter
FILES Parameter
SHELL Parameter
STACKS Parameter
A)Creation of CONFIG.SYS File
You can create the CONFIG.SYS file using the COPY command,
EDLIN (the line editor supplied with DOS), or any other editor or
word processor that can save its text in ASCII format. If you
create it with a word processor, then save it in ASCII or text
format and copy it to the root directory. To put the commands
that you enter into commission, you must reboot your computer
(Ctrl-Alt-Del, or turn the power off and on ).
To create the CONFIG.SYS file using the COPY command, use
the following model:
COPY CON CONFIG.SYS
Before creating a CONFIG.SYS file for a floppy or your hard disk,
make sure that you are in the root directory (\) before you enter
this command.
After typing this command and pressing the Enter key, you
simply type in each configuration command to be processed when
the CONFIG.SYS file is executed. After typing in each command,
you terminate the line by pressing the Enter key.
Once you have entered all of the configuration command
statements you wish to have in this file, you save it on disk (in
the current directory) by pressing Ctrl-Z (you can also
accomplish this by pressing F6 on IBM PCs and most compatibles)
and the Enter key.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
BREAK Status
BUFFERS Parameter
COUNTRY Parameter
Devices, Drivers for
LASTDRIVE Parameter
FCBS Parameter
FILES Parameter
SHELL Parameter
STACKS Parameter
A)BREAK Status(B
Normally, DOS checks for the BREAK key (Ctrl-Break) only
when performing standard input/output or print operations because
the default for the BREAK command is off. If you want DOS to
check for the BREAK key under more circumstances, set the status
to on by entering
BREAK = ON
as a line in the CONFIG.SYS file. Setting the status to on in
this file will allow you to abort program operations that produce
few or no standard device operations (such as running a
compiler). For more information on the BREAK command, refer to
its reference entry in the main text of the book.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
Creation of CONFIG.SYS File
BUFFERS Parameter
COUNTRY Parameter
Devices, Drivers for
ANSI.SYS
LASTDRIVE Parameter
FCBS Parameter
FILES Parameter
SHELL Parameter
STACKS Parameter
A)BUFFERS Parameter
A disk buffer is a specific block of RAM that DOS uses to
store temporarily data that is being read or written to a disk.
The default number of buffers maintained by DOS is 2. In version
3.3, the number of buffers is set according to these criteria:
þ BUFFERS=3 if you have a disk drive whose capacity
is greater than 360K.
þ BUFFERS=5 if your computer has more than 128K RAM.
þ BUFFERS=10 if your computer has more than 256K
RAM.
þ BUFFERS=15 if your computer has more than 512K
RAM.
Only if none of these apply to your computer system is the
default number of buffers set to 2. Each buffer that is added
with the BUFFERS command uses up an additional 528 bytes of
memory.
To open additional buffers, you use the BUFFERS command
followed by the equal sign and the number of buffers to use in
the CONFIG.SYS file. For example, to increase the number of
buffers from 2 to 10, you would enter
BUFFERS = 10
in a line of the CONFIG.SYS file.
Generally, performance is enhanced when running application
programs when you increase the number of buffers from the default
of 2. However, there is a trade-off that can occur when you have
somewhere between 10 and 20 buffers open (depending upon the type
of application that you are using). At that point, it may take
DOS as much time to locate data in a particular memory buffer as
it would to get the data from disk.
Many DOS application programs, such as WordStar 2000 and
dBASE III PLUS, require many more than 2 buffers in order to run.
During installation of such software, the application's
installation program checks the root directory to make sure first
that the CONFIG.SYS exists and, if it does, to check the number
of buffers open with the BUFFERS command. If the number is less
than 20 (or the BUFFER command is not used in the file), the
program will then automatically enter a BUFFERS command or edit
an existing one to read as follows:
BUFFERS = 20
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
Creation of CONFIG.SYS File
BREAK Status
COUNTRY Parameter
Devices, Drivers for
LASTDRIVE Parameter
FCBS Parameter
FILES Parameter
SHELL Parameter
SELECT Command
STACKS Parameter
A)COUNTRY Parameter
You can use the COUNTRY command in a CONFIG.SYS file to
change the currency, date, or time format or the collating
sequence to match that preferred by a foreign country. The syntax
of the COUNTRY command is
COUNTRY = xxx,[yyy],[d:]COUNTRY.SYS
where
xxx Specifies the country code (see SELECT).
yyy Specifies the code page of the desired
country (in DOS 3.3, a country may have
different information depending on the code
page selected- -see Appendix C of the DOS
reference for a listing of the codes).
Note that if you have used the SELECT command, DOS will have
already created a CONFIG.SYS file that includes the COUNTRY
configuration command. To make changes to the COUNTRY codes, you
must then edit the contents of this file using either EDLIN or a
word processor that can read ASCII files.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
Creation of CONFIG.SYS File
BREAK Status
BUFFERS Parameter
Devices, Drivers for
LASTDRIVE Parameter
FCBS Parameter
FILES Parameter
SHELL Parameter
STACKS Parameter
A)Devices, Drivers for
DOS automatically loads device drivers for standard
input/output devices, printers, and storage devices such as
floppy and fixed disk drives. Therefore, you need to use the
DEVICE configuration command in the CONFIG.SYS file only when you
need to install additional nonstandard devices (such as a mouse
or an 8-inch floppy disk drive). The driver files for nonstandard
devices are supplied by the device manufacturer.
To install a new device driver, you enter the DEVICE command
followed by the equal sign and the name of the file that contains
the driver on a line in the CONFIG.SYS file.
The DOS diskette includes two device drivers, ANSI.SYS and
VDISK.SYS. Version 3.3 has added three more device
drivers:DISPLAY.SYS, PRINTER.SYS, and DRIVER.SYS.
ANSI.SYS
The ANSI.SYS driver file extends cursor control and keyboard
reassignments. These extended functions make it easier for
software to control cursor positioning, display messages on the
screen, set colors, and reassign keyboard functions. Some
software applications, such as SuperKey, require that ANSI.SYS be
loaded by theCONFIG.SYS file in order to run.
To add this driver, you enter
DEVICE = [d:][path]ANSI.SYS
on a line of your CONFIG.SYS file, where
d:path Specifies the drive and path.
VDISK.SYS
The VDISK.SYS driver allows you to set up a virtual or RAM
disk that performs the functions of a physical disk drive. A
virtualdisk, however, is installed in RAM and, therefore,
disappears when power is interrupted to the computer system. You
can install more than one virtual disk using the VDISK.SYS
driver, depending upon the amount of RAM available to your
system.
The syntax of the DEVICE configuration command when using
the VDISK.SYS driver is as follows:
DEVICE = [d:][path]VDISK.SYS [comment][bbb]
[comment][sss][comment][ddd][/E[:m]]
Before explaining each optional parameter, consider the
following example that uses all of the options:
DEVICE = C:\DOS\VDISK.SYS buffer size=256
sector size=512 directory entries=128 /E
The options are as follows:
d:path Tells DOS where the VDISK.SYS file is
located (C:\DOS in the example).
bbb Sets the size of the virtual disk in
kilobytes. If you do not specify this
parameter, DOS uses a default of 64K.
You can enter a value between 1K and the
amount of memory available to your
computer. Notice that you can also add
an optional [comment] explaining the
value. In the example, the comment
buffer size= precedes the value in
kilobytes.
sss Sets the sector size in bytes. The
default of 128 bytes is used by DOS if
this parameter is omitted or an
inaccurate value is entered. Allowable
values for the sector size are 128, 256,
or 512 bytes. The sector size parameter
can also be preceded by an optional
comment. In the example, the comment
sector size= has been added.
ddd Sets the number of directory entries
that the virtual disk can hold (one
directory entry per file copied to the
virtual disk). The default is 64, and
you can enter a value between 2 and 512.
However, DOS may automatically adjust
the value you enter when installing the
virtual disk. The value is increased to
the nearest sector boundary (as set by
the sector size). It is decreased if the
size of the virtual disk (as set by the
buffer size) is too small to accommodate
the file allocation table, the
directory, and two additional sectors.
If the directory size reaches 1 and
these files still cannot be
accommodated, you will receive an error
message and the virtual disk will not be
installed.
comment You may enter an optional comment before
the [ddd] parameter. In the example, the
comment directory entries= has been
added.
/E Tells DOS to install the virtual disk in
extended memory AM at or beyond 1
megabyte). This parameter can only be
used with a personal computer that has
extended memory, such as the IBM PC AT
or PS/2 machines (computers equipped
with an add-on board such as the Intel
Above Board support expanded instead of
extended memory). When you add the /E
parameter, the virtual disk buffer is
established in extended memory while the
device driver is installed in
conventional memory. Extended memory up
to 4 megabytes may be used for a single
virtual disk.
:m Specifies the maximum number of sectors
(as specified by the sss parameter) of
data that are transferred to the virtual
disk at one time. The permissible values
are 1 through 8, with 8 being the
default value.
When a virtual disk is established in extended memory,
interrupt servicing is suspended during data transfers. In some
situations, this can result in some interrupts being lost. If
this happens, you should install the virtual disk in conventional
memory. If the problem is resolved, you can then resinstall the
virtual disk in extended memory with a smaller [:m] value.
When you establish a virtual disk, DOS assigns it the next
available drive letter specification. For example, if your
computer has two floppy disk drives, A and B, the virtual disk
will be given C as the drive letter specification. If you have a
single fixed disk, C, the virtual disk will be given D as the
drive letter specification.
DISPLAY.SYS
The DISPLAY.SYS device driver allows you to use code page
switching on the EGA and IBM PS/2 displays and the IBM
Convertible LCD screen. This device driver is included only in
version 3.3 of DOS, which supports code page switching (see the
CHCP and NLSFUNC command reference entries), and it is used only
when you need to switch from the standard for U.S. symbols to new
code pages containing international symbols.
The syntax of the DISPLAY.SYS DEVICE configuration command
is as follows:
DEVICE = [d:][path]DISPLAY.SYS CON[:]=
(type[,[hwcp][,(n,m)]])
The options are as follows:
d:path Specifies the drive letter and path that
contain the DISPLAY.SYS file.
type Specifies the display adapter type. You can
use MONO, CGA, EGA, and LCD. Use EGA if you
have an IBM PS/2 display (VGA is not yet
fully supported).
hwcp Specifies the code page. Permissible values
are 437, 850, 860, 863, and 865 (refer to
Appendix C of the DOS documentation for a
description of these code page values).
n Specifies the number of prepared code pages
that can be supported. This must be a value
between 0 and 12 (refer to the table in the
DOS documentation for the DISPLAY.SYS command
to determine this value).
m Specifies the number of subfonts supported by
each code page (refer to the table in the DOS
documentation for the DISPLAY.SYS command to
determine this value).
Note that if you are using ANSI.SYS with DISPLAY.SYS, the DEVICE
= ANSI.SYS statement must precede the configuration statement
DEVICE = DISPLAY.SYS in the CONFIG.SYS file.
PRINTER.SYS
The PRINTER.SYS device driver allows you to use code page
switching on the IBM Proprinter Model 4201 and the IBM
Quietwriter III Model 5202. Like the DISPLAY.SYS file, this
device driver is included only in version 3.3 of DOS, which
supports code page switching (see the CHCP and NLSFUNC command
reference entries), and it is used only when you need to switch
from the standard for U.S. symbols to new code pages containing
international symbols.
The syntax of the PRINTER.SYS DEVICE configuration command
is as follows:
DEVICE = [d:][path]PRINTER.SYS LPT#[:]=
(type[,[(hwcp1,hwcp2,...)][,n,]])
The options are as follows:
d:path Specifies the drive letter and path
that contain the PRINTER.SYS file.
LPT# Specifies the printer device. It
can be entered up to three times
(for LPT1, LPT2, and LPT3). You can
substitute PRN for LPT in the
command line.
type Specifies the type of printer use.
You can choose between 4201 (IBM
Proprinter) or 5202 (IBM
Quietwriter III).
(hwcp1,hwcp2,...) Specifies the code page that is
built into the hardware. The
permissible values are 437, 850,
860, 863, and 865 (refer to the
PRINTER.SYS command in the DOS
documentation for an explanation of
how these code page values are
applied to the two printer types).
n Specifies the number of additional
code pages that can be prepared.
This value determines the number of
buffers that PRINTER.SYS will set
up to hold the code pages being
prepared. The maximum number that
can be specified is 12.
DRIVER.SYS
The DRIVER.SYS statement in the CONFIG.SYS file allows you
to access and use a disk device by referring to a logical drive
letter. The syntax used when adding this to the CONFIG.SYS file
isas follows:
DEVICE = DRIVER.SYS /D:ddd[/T:ttt][/S:ss][/H:hh]
[/C][/N][/F:f]
The options are as follows:
/D:ddd Specifies the physical drive number between 0
and 255. The first physical diskette drive
(drive A) has the value 0. The second
physical diskette drive (drive B) has the
value 1. The third physical diskette drive
(must be external) has the value 2. The first
fixed drive has the value 128 and the second
has the value 129.
/T:ttt Specifies the number of tracks per side
between 1 and 999 (default: 80).
/S:ss Specifies the number of sectors per track
between 1 and 99 (default: 9).
/H:hh Specifies the number of drive heads between 1
and 99 (default: 2).
/C Specifies that changeline support is required
(only used on computers such as the IBM PC AT
that support diskette changeline).
/N Specifies that the physical device is a non-
removable block device (such as a fixed
disk).
/F:f Specifies the device type (form factor). The
value of the f parameter is determined as
follows:
Device Value
160K/180K 0
320K/360K 0
1.2 megabytes 1
720K or others 2
1.44 megabytes 7
Note that the DEVICE=DRIVER.SYS configuration statement is
not used to drive fixed (hard) disks. To set a logical drive
letter for a fixed disk, use the SUBST command (see the SUBST
reference entry for more information).
To find out the logical drive letter assigned by DOS to the
device driver for a particular computer configuration and value
of /D:, refer to the table included in the DOS documentation
under the reference entry for the DEVICE command.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
Creation of CONFIG.SYS File
BREAK Status
BUFFERS Parameter
COUNTRY Parameter
LASTDRIVE Parameter
FCBS Parameter
FILES Parameter
SHELL Parameter
STACKS Parameter
A)LASTDRIVE Parameter
The highest drive specification letter that DOS 3 will
recognize is drive E (three fixed drives attached: C, D, and E).
If your system has more than this number of logical or physical
drives attached, you must add a LASTDRIVE statement to your
CONFIG.SYS file:
LASTDRIVE = x
where
x Specifies a letter between A and Z. If the drive
letter you specify is less than the number of
drives attached to your system, DOS will ignore
the LASTDRIVE statement in the CONFIG.SYS file.
For example, if you are on a network and you have 15 drive
volumes attached to the system, you would enter
LASTDRIVE = O
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
Creation of CONFIG.SYS File
BREAK Status
BUFFERS Parameter
COUNTRY Parameter
Devices, Drivers for
FCBS Parameter
FILES Parameter
SHELL Parameter
STACKS Parameter
A)FCBS Parameter
Some older application programs use file control blocks
(FCBs) instead of the newer file handles to create, open, and
delete files as well as to read from and write to files. When
using these programs on a network with file sharing in use, you
may have to increase the number of files that can be opened by
FCBs. The default value used by DOS is 4 files.
To specify a new number of files that can be concurrently
open by DOS, you use the FCBS command in the CONFIG.SYS file:
FCBS = x,y
where
x Specifies the total number of files that can
be opened by FCBs.
y Specifies the number of files protected from
automatic closure by DOS (the default is 0).
When file sharing is in use and an application program tries
to open more than the total number of files, DOS closes the
least-recently used file and opens the new file (excluding the
files protected from automatic closure). If the program tries to
read from or write to a file that has been closed by DOS, you
will receive the following error message:
FCB unavailable
Abort, Fail?
To avoid such an error, you would add a FCBS command to your
CONFIG.SYS file. For example, entering
FCBS = 10,5
would allow 10 FCB files to be open concurrently and would
protect 5 of these from automatic closure.
When specifying the first parameter (the total number of FCB
files), you can enter a value between 1 and 255. When specifying
the second parameter (the number of files protected from
automatic closure), you can enter a value between 0 and 255. (See
also the SHARE command in the main text.)
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
Creation of CONFIG.SYS File
BREAK Status
BUFFERS Parameter
COUNTRY Parameter
Devices, Drivers for
LASTDRIVE Parameter
FILES Parameter
SHARE Command
SHELL Parameter
STACKS Parameter
A)FILES Parameter
By default, DOS allows up to 8 files (controlled by file
handles, not FCBs) to be open concurrently. This number is
insufficient to run several newer application programs as well as
some DOS commands (such as XCOPY).
If you receive either the error message
Too many open files
or
Too many files open
you will have to use the FILES configuration command in the
CONFIG.SYS file to increase the maximum number of files available
to the entire system:
FILES = n
where
n Specifies the number of files that can be
opened at the same time (a value between 8
and 255). However, be aware that the maximum
number of files that a single process can
have opened is set at 20.
To accommodate 15 different files being open at one time, you
would enter
FILES = 15
as a line in the CONFIG.SYS file.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
Creation of CONFIG.SYS File
BREAK Status
BUFFERS Parameter
COUNTRY Parameter
Devices, Drivers for
LASTDRIVE Parameter
FCBS Parameter
SHELL Parameter
STACKS Parameter
XCOPY Command
A)SHELL Parameter
Normally, DOS loads the command processor from the
COMMAND.COM file during the boot sequence. If you have your own
command processor, you can have it initialized and loaded at
start-up in place of COMMAND.COM by using the SHELL configuration
command.
The syntax of the SHELL command is
SHELL = [d:][path]filename [/E:xxxxx][/P]
where
d:pathfilename Specifies the file name of the new
command processor (including its
path, if it is not located in the
root directory). Using COM-MAND.COM
as the file name is a convenient
way to increase the environment
size under DOS 3.2 and 3.3.
/E:xxxxx Specifies the number of bytes for
the environment size (expressed as
a base-10 integer between 160 and
32768).
/P Causes COMMAND.COM to remain loaded
and to execute the AUTOEXEC.BAT
file (if one exists).
Note that using the SHELL command to run a different command
processor does not affect the COMSPEC command, which points to
the name of the controlling processor (see SET in the reference
entries). If you use the SHELL command in the CONFIG.SYS file to
load a new command processor, you will also want to use the
COMSPEC parameter in the SET command in the AUTOEXEC.BAT file to
refer to it.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
Creation of CONFIG.SYS File
BREAK Status
BUFFERS Parameter
COUNTRY Parameter
Devices, Drivers for
LASTDRIVE Parameter
FCBS Parameter
FILES Parameter
STACKS Parameter
A)STACKS Parameter
DOS 3.3 includes a STACKS configuration command that allows
you to override the default stack resources used by DOS. The
syntax of this command is
STACKS = n,s
where
n Specifies the number of stack frames between
8 and 64.
s Specifies the size in bytes of each stack
frame between 32 and 512.
If the STACKS command is not included in the CONFIG.SYS
file, the n and s parameters are set to 0 for the IBM PC, IBM PC
XT, and the IBM Portable PC. For all other IBM personal
computers, the default values are n = 9 and s = 128.
Every time a hardware interrupt occurs, DOS appropriates one
stack frame from the stack pool. Once the interrupt has been
processed, DOS returns the stack frame to the pool. If you
experience stack overflow errors, you should use the STACKS
command to increase the number of stack frames available to DOS.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
CONFIG.SYS File
Creation of CONFIG.SYS File
BREAK Status
BUFFERS Parameter
COUNTRY Parameter
Devices, Drivers for
LASTDRIVE Parameter
FCBS Parameter
FILES Parameter
SHELL Parameter
A)Hard Disk Partitions
Hard disks are usually so large that they can contain more
than one type of operating system. For example, you can have DOS
3.3 manage one part of a disk and UNIX manage another. Each of
these sections is called a partition. You can have from one to
four partitions on a disk.
Partitions are used to make the hard disk, especially a very
large one, a more economical investment. They allow you to
effectively have up to four completely different computer systems
resident in one set of hardware. However, since they do not share
a common software environment, they cannot share data directly.
Two types of partitions can be set up for DOS: a primary DOS
partition and an extended DOS partition. The primary DOS
partition is the partition that contains DOS and is the first
partition on the disk. This is the only partition that must be on
the disk if your disk is no larger than 32 megabytes. The
extended DOS partition is a separate partition that cannot be
used for booting, but can be divided into separate logical
drives.
If you have more than 32 megabytes available on one hard
disk, you will need to create an extended DOS partition, which is
assigned the next logical drive letter. For example, if you had a
60-megabyte hard disk drive, and wanted access to all of it, you
would create a 32-megabyte primary partition and a 28-megabyte
extended partition. The primary partition could be accessed as
drive C, while the extended partition would be called drive D.
You could also subdivide the extended partition into more logical
drives (up to the letter Z).
You must create partitions before using a hard disk drive.
You will probably take the easiest route by simply making the
entire disk into one primary partition. The FDISK program
presented here, however, is necessary in several more advanced
situations. For example, you may plan on using multiple operating
systems from the same disk. FDISK will let you set up unique
partitions for each system. (Each of these would be a primary
partition, but only one could be designated the active partition,
the one that will gain control at boot up.) Then again, you may
be using one of the large hard disks (40 to 70 megabytes) that
are increasingly common. Since DOS can only access a logical
drive of 32 megabyte or less, you'll need to partition a larger
physical drive into multiple logical drives. Only in this way can
you store and retrieve information on the larger hard disk.
Note: If your disk is already being used and you wish to
make a new partition, you will have to first back up all of your
data and then run FDISK from a system diskette. Finally, you'll
need to reformat your disk before restoring your files to it.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Configuration of DOS Partitions
Active Partitions, Changing of
Displaying of Partition Information
Deletion of DOS Disk Partitions
A)Configuration of DOS Partitions
In this section, you will see exactly how to use the FDISK
command. This procedure is very important, and it can have
serious consequences if done incorrectly. However, it can also
make your system more efficient, when done properly. FDISK is
only usable on hard disk systems.
Invoking the FDISK command is as simple as typing
FDISK
and pressing Return. emember to have your path set properly to
include the directory containing the FDISK command file.) After
this command creates the appropriate partition(s), you must then
logically format the disk.
Warning: All data on your disk will be destroyed when you
create partitions with FDISK.
When you first execute FDISK, the screen will clear and the
FDISK Options screen will appear. This contains the menu used to
get around in FDISK, as shown in the screen below.
----------------------------------------------------------------
FDISK Options
Current Fixed Disk Drive: 1
Choose one of the following:
1. Create DOS partition
2. Change Active Partition
3. Delete DOS partition
4. Display Partition Information
Enter choice: [1]
Press ESC to return to DOS
----------------------------------------------------------------
As you can see, there are four choices. If you have a system
with more than one hard disk drive, the number in the Current
Fixed Disk Drive: 1 line would be changed to the number of drives
in your system. Also, a fifth option, Select Next Fixed Disk
Drive, would be displayed on the screen. You can work on only one
hard disk drive at a time, but you can switch from the drive you
are working on to another drive. For now, let's assume you have
one hard disk drive and that the screen below is what you see.
Creating a Partition
The first option on the FDISK Options menu is to create a
DOS partition. Since you are using DOS, and not another operating
system such as UNIX, you can only create DOS partitions. Should
you wish to put another operating system onto the disk, that
system would have its own version of FDISK and could then create
its own partitions next to DOS'.
Tip: If you plan to use your hard disk to support another
operating system, do not partition the whole disk. Leave some
room so that another system can be loaded onto the disk.
Choosing the first option to create a DOS partition results
in the screen below.
----------------------------------------------------------------
Create DOS Partition
Current Fixed Disk Drive: 1
1. Create Primary DOS partition
2. Create Extended DOS partition
Enter Choice: [1]
Press ESC to return to FDISK Options
----------------------------------------------------------------
If you select option 2 at this point, intending to create an
extended DOS partition before creating a primary partition, DOS
will display a message indicating that you cannot do so, and will
suggest that you press Esc to return to the main FDISK Options
menu. Assuming you are starting from scratch, you would select
choice 1 to create the primary DOS partition. You will then see
the screen shown below.
----------------------------------------------------------------
Create Primary DOS Partition
Current Fixed Disk Drive: 1
Do you wish to use the maximum size
for a DOS partition and make the DOS
partition active (Y/N).........? [n]
Press ESC to return to FDISK Options
----------------------------------------------------------------
If you want to use the whole disk for DOS, then you answer Y
on this screen. Doing so makes DOS use the whole disk. The
computer will allocate the entire disk, and then come back with
the message
System will now restart
Insert DOS diskette in drive A:
Press any key when ready . . .
Since you just created the partition, there is still nothing on
the hard disk. The system must be rebooted from the disk drive.
You can now format the entire hard disk just as you would a
floppy diskette.
If you answer N, you have the opportunity to create a
smaller partition, as shown in the screen below. As you can see,
there are 305 cylinders available on the total disk. A hard disk
consists of several platters, similar to a diskette; each platter
consists of a series of concentric tracks made up of sectors.
Each platter lies above another and is read by a different disk
head. Viewed vertically, a series of tracks (with the same track
number, but on different platters) located one above the other
constitute a cylinder. The brackets in the screen shown below
indicate the place where you may enter a number for cylinders
that is less than the default maximum (305 on this disk).
----------------------------------------------------------------
Create Primary DOS Partition
Current Fixed Disk Drive: 1
Total disk space is 305 cylinders.
Maximum space available for partition
is 305 cylinders.
Enter partition size...........: [ 200]
No partitions defined
Press ESC to return to FDISK Options
----------------------------------------------------------------
Notice that the second-to-last line on the screen tells you
that no partitions have been defined yet. If you are using your
disk for DOS alone, you should accept the default maximum
cylinder value. All disk space will then be available for DOS and
your DOS files. If you plan on splitting up your disk between DOS
and another operating system, however, you'll have to decide for
yourself what percentage of total disk space is needed for the
other operating system. In this example, you intend to create an
extended DOS partition, so 200 was entered for the number of
cylinders in the primary DOS partition.
Entering 200 results in the screen shown below. This screen
tells you that the first partition on drive C is a primary DOS
partition (PRI DOS) that starts at cylinder 0 and ends at
cylinder 199, constituting a total of 200 cylinders.
----------------------------------------------------------------
Create Primary DOS Partition
Current Fixed Disk Drive: 1
Partition Status Type Start End Size
C: 1 PRI DOS 0 199 200
Primary DOS partition created
Press ESC to return to FDISK Options
----------------------------------------------------------------
Pressing Esc at this point returns you to the FDISK Options
menu. If you again try to create a primary partition, DOS will
show the following message on your screen:
Primary DOS partition already exists.
Press ESC to return to FDISK Options
Note: There can only be one primary DOS partition. When DOS
boots up, the system files from this partition are loaded into
memory for your operations. In this example, you have only used
200 cylinders out of a possible 305, so you can make an extended
DOS partition. To do so, you select choice 1 (create a DOS
partition) on the FDISK Options menu and then select choice 2
(create Extended DOS partition) on the Create DOS Partition menu.
The resulting screen, shown below, allows you to create an
extended DOS partition. This screen tells you the current
partition information- -that is, that there are 305 total
cylinders available for use- -and also tells you that 105
cylinders remain unused. The 105 value is used as the default
entry at this stage. You only need to type in a number over the
105 to override the default. In the screen below, 55 was entered
for the desired extended DOS partition, leaving 50 cylinders
unused on the disk for another operating system.
----------------------------------------------------------------
Create Extended DOS Partition
Current Fixed Disk Drive: 1
Partition Status Type Start End Size
C: 1 PRI DOS 0 199 200
Total disk space is 305 cylinders.
Maximum space available for partition
is 105 cylinders.
Enter partition size............: [ 55]
Press ESC to return to FDISK Options
----------------------------------------------------------------
The screen will now clear, redisplay the partition
information (including that on the new extended DOS partition),
and print the message
Extended DOS Partition created
Press ESC to return to FDISK Options
near the bottom of the screen. Pressing Esc will result in the
next step of the process (see screen below).
----------------------------------------------------------------
Create Logical DOS Drive(s)
No logical drives defined
Total partition sized is 55 cylinders.
Maximum space available for logical
drive is 55 cylinders.
Enter logical drive size..........: [ 45]
Press ESC to return to FDISK Options
----------------------------------------------------------------
Since you have just created an extended DOS partition, DOS
wants to know if you want to create logical drives within this
new partition. It tells you the total available cylinders in the
partition and asks you to enter a size for the logical drive. In
this example, you enter 45. The resulting screen will contain the
logical drive information (drive name, starting cylinder, ending
cylinder, and total cylinders used).
Suppose you wanted to create another logical drive, E, using
the remaining ten cylinders. You could again choose option 1 on
the FDISK Options menu. You would go again to the Create DOS
Partition menu, but there would be one new choice displayed:
3. Create logical DOS drive(s) in
the Extended DOS partition
This would bring you back to the screen for defining logical
drives, where you could then enter the information for drive E.
Going through this same sequence again in order to use the
remaining ten cylinders will result in the screen below. Notice
that the cylinder numbers are within the bounds of the extended
DOS partition. You are told that DOS created two logical drives,
D and E, with sizes of 45 and 10 cylinders. Furthermore, you're
reminded that no more available space remains for any other
logical drives. Press Esc, and you will once again be back at the
FDISK Options menu.
----------------------------------------------------------------
Create Logical DOS Drive(s)
Drv Start End Size
D: 200 244 45
E: 245 254 10
All available space in the Extended DOS
partition is assigned to logical drives.
Logical DOS drive created, drive letters
changed or added
Press ESC to return to FDISK Options
----------------------------------------------------------------
If you try to create another extended partition, you will
get a partition information screen and the message
Extended DOS partition already exists.
Press ESC to return to FDISK Options
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Active Partitions, Changing of
Deletion of DOS Disk Partitions
Displaying of Partition Information
FDISK Command
Hard Disk Partitions
A)Active Partitions, Changing of
The active partition is the partition that is used to boot
the system. It is the default partition. Choosing option 2 on the
main FDISK Options menu leads you to a menu like that shown in
the screen below, in which the partition information is displayed
along with the total number of cylinders available on the disk.
FDISK now wants to know the number of the partition that you wish
to make active.
----------------------------------------------------------------
Change Active Partition
Current Fixed Disk Drive: 1
Partition Status Type Start End Size
C: 1 PRI DOS 0 199 200
2 EXT DOS 200 254 55
Total disk space if 305 cylinders.
Enter the number of the partition you
want to make active.............: [2]
Partition selected (2) is not bootable,
active partition not changed.
Press ESC to return to FDISK Options
----------------------------------------------------------------
If you enter the number 2, as shown in the figure, DOS will
inform you that only the primary DOS partition (1) may be made
active. Type the number 1 so that the primary DOS partition will
have control when the system comes up. Pressing Return will
result in the adjusted partition information display seen below.
----------------------------------------------------------------
Change Active Partition
Current Fixed Disk Drive: 1
Partition Status Type Start End Size
C: 1 A PRI DOS 0 199 200
2 EXT DOS 200 254 55
Total disk space is 305 cylinders.
Partition 1 made active
Press ESC to return to FDISK Options
----------------------------------------------------------------
Notice the letter A on the first line of this display. An A
under Status tells you that partition 1 is the active partition.
Pressing Esc takes you back to the FDISK Options menu.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Configuration of DOS Partitions
Deletion of DOS Disk Partitions
Displaying of Partition Information
FDISK Command
Hard Disk Partitions
A)Displaying of Partition Information
Option 4 on the FDISK Options menu is used to display
information about the partitions. This is useful because no extra
functions will be executed at the same time; you can simply look
at the information. Choosing option 4 yields the screen shown
below.
----------------------------------------------------------------
Display Partition Information
Current Fixed Disk Drive: 1
Partition Status Type Start End Size
C: 1 A PRI DOS 0 199 200
2 EXT DOS 200 254 55
Total disk space is 305 cylinders.
The Extended DOS partition contains
logical DOS drives. Do you want to
display logical drive information? [Y]
Press ESC to return to FDISK Options
----------------------------------------------------------------
The information at the top of the screen is familiar by now.
But what if you want to see information about the logical drives
that have been defined? Look at the bottom half of the screen,
where you are asked if you want to see this information. Replying
with Y results in a display of information about these logical
drives (see the screen below). Pressing Esc at this point will
return you to the FDISK Options menu.
----------------------------------------------------------------
Display Logical DOS Drive Information
Drv Start End Size
D: 200 244 45
E: 245 254 10
Press ESC to return to FDISK Options
----------------------------------------------------------------
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Active Partitions, Changing of
Configuration of DOS Partitions
Deletion of DOS Disk Partitions
FDISK Command
Hard Disk Partitions
A)Deletion of DOS Disk Partitions
As with most things, what DOS giveth, DOS can taketh away- -
with a little prodding from you. Selecting choice 3 on the FDISK
Options menu produces the Delete DOS Partition menu, shown below.
----------------------------------------------------------------
Delete DOS Partition
Current Fixed Disk Drive: 1
Choose one of the following:
1. Delete Primary DOS partitions
2. Delete Extended DOS partition
3. Delete logical DOS drive(s) in
the Extended DOS Partition
Enter choice: [ ]
Press ESC to return to FDISK Options
----------------------------------------------------------------
Using this menu, you can delete any of the information
you've already set up. You may want to expand or contract other
partitions, or you may no longer want to use a partition in the
manner you originally designed. In any case, you can only make
changes in a certain order. You cannot delete the primary DOS
partition without first deleting the extended DOS partition. If
you try, DOS will give you this message:
Cannot delete Primary DOS partition on
drive 1 when Extended partition exists
Press ESC to return to FDISK Options
In addition, you cannot delete an extended DOS partition
without first ``undefining'' (deleting) the logical drives in
that partition. Trying to delete the extended DOS partition
before deleting the drives in it will simply display the current
partition information with the patient message
Cannot delete Extended DOS partition
while logical drives exist.
Press ESC to return to FDISK options
Choice 3 in the Delete DOS Partition menu is probably the
first selection you will need to make; you work your way
backwards through the order in which you created things.
ctually, you will find that this is a fairly natural process.)
Selecting choice 3 produces the screen shown below, which
contains the logical drive information and the size of the
extended DOS partition the drives are in. You are also warned
that any data contained in the logical disk drive to be deleted
will also be deleted. If you still want to delete the drive,
simply enter the drive identifier. You will then be asked to
confirm this step. In the screen below, you have selected drive E
to delete first, and confirmed the choice by typing Y. If you had
entered N, you would have been returned to the FDISK Options
menu.
----------------------------------------------------------------
Delete Logical DOS Drive
Drv Start End Size
D: 200 244 45
E: 245 254 10
Total partition size is 55 cylinders.
Warning! Data in the logical DOS drive
will be lost. What drive do you wish
to delete.........................? [e]
Are you sure......................? [y]
Press ESC to return to FDISK Options
----------------------------------------------------------------
Once FDISK deletes the logical drive, it updates the display
at the top of the screen and asks for another drive to delete. If
you wanted to regain all the space used by this partition, you
would then enter drive D, confirm your entry, and end up with the
screen shown below. Pressing Esc twice at this point would
bring you back up through the menu screens to the main FDISK
Options menu.
----------------------------------------------------------------
Delete Logical DOS Drive
Drv Start End Size
D: drive deleted
E: drive deleted
Total partition size is 55 cylinders.
All logical drives deleted in the
Extended DOS partition
Press ESC to return to FDISK Options
----------------------------------------------------------------
Now that the logical drives are gone, you can delete the
extended DOS partition itself if you choose to do so. Choosing
option 2 on the Delete DOS Partition menu results in the familiar
form of an FDISK screen (see below). Again, you are shown the
partition information display, warned that data will be lost, and
asked if you really want to delete the extended DOS partition.
----------------------------------------------------------------
Delete Extended DOS Partition
Current Fixed Disk Drive: 1
Partition Status Type Start End Size
C: 1 A PRI DOS 0 199 200
2 EXT DOS 200 254 55
Warning! Data in the Extended DOS
partition will be lost. Do you wish
to continue.......................? [y]
Press ESC to return to FDISK Options
----------------------------------------------------------------
If you reply Y, the screen will be updated to show only the
primary DOS partition and the message
Extended DOS partition deleted
Press ESC to return to FDISK Options
Press Esc to return once again to the FDISK Options menu.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Active Partitions, Changing of
Configuration of DOS Partitions
Displaying of Partition Information
FDISK Command
Hard Disk Partitions
A)active partition
The section of a hard disk containing the operating system to be
used when the hardware powers up.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
hard disk
hardware
A)ANSI driver
A device driver, contained in the ANSI.SYS file, that loads
additional support for advanced console features.
A)application program
A program that performs or replaces a manual function, such as
balancing a checkbook or managinginventory.
A)archive bit
A bit in a file specification used to indicate whether the file
in question needs to be backed up.
A)ASCII
American Standard Code for Information Interchange. The coding
scheme whereby every character the computer can access is
assigned an integer code between 0 and 255.
A)assembly language
A symbolic form of computer language used to program computers at
a fundamental level.
A)asynchronous communications
See serial communications.
A)AUTOEXEC.BAT
A batch file executed automatically whenever the computer is
booted up.
A)background task
A second program running on your computer; usually, a printing
operation that shares the CPU with your main foreground task.
A)base name
The portion of a file name to the left of the period separator;
it can be up to eight characters long.
A)BASIC
Beginner's All-purpose Symbolic Instruction Code. A computer
language similar to the English language.
A)batch file
An ASCII file containing a sequence of DOS commands that, when
invoked, will assume control of the computer, executing the
commands as if they were entered successively by a computer user.
A)baud rate
The speed of data transmission, usually in bits per second.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
bit
binary
byte
A)binary
A numbering system that uses powers of 2 to generate all other
numbers.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
baud rate
bit
byte
A)bit
One-eighth of a byte. A bit is a binary digit, either 0 or 1.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
baud rate
binary
A)bit mapping
The way a graphics screen is represented in the computer. Usually
signifies point-to-point graphics.
A)booting up
See bootstrapping.
A)boot record
The section on a disk that contains the minimum information DOS
needs to start the system.
A)bootstrapping
When the computer initially is turned on or is rebooted from the
keyboard with Ctrl-Alt-Del, it ``pulls itself up by its
bootstraps.'' See also warm booting, cold booting.
A)branching
The transfer of control or execution to another statement in a
batch file. See also decision making.
A)Break key
The control-key combination that interrupts an executing program
or command; activated by pressing the Scroll Lock/Break key while
holding down the Ctrl key.
A)buffer
An area in memory set aside to speed up the transfer of data,
allowing blocks of data to be transferred at once.
A)byte
The main unit of memory in a computer. A byte is an 8-bit binary-
digit number. One character usually takes up one byte.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
binary
bit
baud rate
A)cache
A portion of memory reserved for the contents of recently
referenced disk sectors. Facilitates faster reaccess of the
same sectors.
A)case sensitivity
Distinguishing between capital letters and lowercase letters.
A)chaining
Passing the control of execution from one batch file to another.
This represents an unconditional transfer of control.
A)character set
A complete group of 256 characters can be used by programs or
system devices. Consists of letters, numbers, control codes, and
special graphics or international symbols. See also code page.
A)cluster
A group of contiguous sectors on a disk. This is the smallest
unit of disk storage that DOS can manipulate.
A)COBOL
A programming language usually used for business applications.
A)code page
A character set that redefines the country and keyboard
information for non-n-U.S. keyboards and systems.
A)cold booting
When the computer's power is first turned on and DOS first boots
up. See bootstrapping.
A)COMMAND.COM
The command processor that comes with DOS.
A)command line
The line on which a command is entered. This line contains the
command and all of its associated parameters and switches. It may
run to more than one screen line, but it is still one command
line.
A)command processor
The program that translates and acts on commands.
A)compressed print
Printing that allows more than 80 characters on a line of output
(usually 132 characters, but on newer printers up to255
characters per line).
A)computer-aided design (CAD) program
A sophisticated software package containing advanced graphics and
drawing features.Used by engineers, architects, and designers for
drawing and de-sign applications.
A)concatenation
The placing of two or more text files together in a series.
A)conditional statement
A statement in a batch file that controls the next step to be
executed in the batch file, based on the value of a logical test.
A)CONFIG.SYS
An ASCII text file containing system configuration commands.
A)configuration
An initial set of system values, such as the number of buffers
DOS will use, the number of simultaneously open files it will
allow, and the specific devices that will be supported.
A)console
The combination of your system's monitor and keyboard.
A)contiguity
That the disk sectors used by a file are physically adjacent on a
disk.
A)control codes
ASCII codes that do not display a character but perform a
function, such as ringing a bell or deleting a character.
A)copy protection
Special mechanisms contained in diskettes to inhibit the copying
of them by conventional commands.
A)CPU
Central Processing Unit. The main chip that executes all
individual computer instructions.
A)Ctrl-Z
The end-of-file marker.
A)cursor
The blinking line or highlighted box that indicates where the
next keystroke will be displayed or what the next control code
entered will affect.
A)cutting and pasting
Selecting text from one part of a document or visual display and
moving it to another location.
A)cylinder
Two tracks that are in the same place on different sides of a
double-sided disk. May be extended to include multiple platters.
For example, Side 0 Track 30, Side 1 Track 30, Side 2 Track 30,
and Side 3 Track 30 form a cylinder.
A)daisy-wheel printer
A printer that uses circular templates for producing letter-
quality characters.
A)data area
The tracks on a disk that contain user data.
A)database
A collection of data organized into various categories. A phone
book is one form of database.
A)database management system
A software program designed to allow the creation of specially
organized files, as well as data entry, manipulation, removal,
and reporting for those files.
A)data bits
The bits that represent data when the computer is communicating.
A)data disk
A disk that has been formatted without the /S switch. The disk
can contain only data; no room has been reserved for system
files.
A)data stream
The transmission of data between two components or computers.
A)dead key
A reserved key combination on international keyboards, which
outputs nothing itself but allows the next keystroketo produce an
accent mark above or below the keystroke's usualcharacter.
A)debugging
The process of discovering what is wrong with a program, where
the problem is located, and what the solution is.
A)decimal
A numbering system based on ten digits.
A)decision making
A point in a batch file at which execution can continue on at
least two different paths, depending on the results of a program
test. Also known as logical testing or branching.
A)default
The standard value of a variable or system parameter.
A)deferred execution
In a program or batch file, when execution is delayed until a
value for some parameter is finally entered or computed.
A)delimiter
A special character, such as a comma or space, used to separate
values or data entries.
A)destination
The targeted location for data, files, or other information
generated or moved by a DOS command.
A)device
Any internal or external piece of peripheral hardware.
A)device driver
Also known as an interrupt handler. A special program that must
be loaded to use a device. Adds extra capability to DOS.
A)device name
Logical name that DOS uses to refer to a device.
A)digital
A representation based on a collection of individual digits, such
as 0s and 1s in the binary number system.
A)digitizer
A device with a movable arm that can take an image and break it
up into small parts, which the computer translates into bits.
A)directory
A grouping of files on a disk. These files are displayed together
and may include access to other directories (subdirectories).
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
directory tree
file
path
subdirectory
A)directory tree
The treelike structure created when a root directory has several
subdirectories, each of the subdirectories has subdirectories,
and so on.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
directory
file
path
subdirectory
A)disk drive
A hardware device that accesses the data stored on a disk.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
hardware
A)diskette
A flexible, oxide-coated disk used to store data. Also called a
floppy diskette.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
disk drive
hardware
A)disk optimizer
A program that rearranges the location of files stored on a disk
in order to make the data in those files quickly retrievable.
A)DOS
Disk Operating System. A disk manager and the program that allows
computer/user interaction.
A)DOS environment
A part of memory set aside to hold the defaults needed in the
current environment, such as COMSPEC, PATH, LASTDRIVE, and so on.
A)DOS prompt
Usually C or A. The visual indication that DOS is waiting for a
command or prompting you for input.
A)dot-matrix printer
A printer that represents characters by means of tiny dots.
A)double-density diskette
A diskette on which magnetic storage material is arranged twice
as densely as usual, allowing the storage of twice the usual
amount of data. Generally refers to a 360K, 5-inch diskette.
A)drive identifier
A single letter assigned to represent a drive, such as drive A or
drive B. Usually requires a colon after it, such as A:.
A)DRIVER.SYS
A file containing a device driver for an extra external disk
drive. Used in the CONFIG.SYS file.
A)dual tasking
Causing two tasks or programming events to occur simultaneously.
A)echoing
Displaying on your video monitor the keystrokes you type in.
A)EDLIN
The DOS line editor.
A)end-of-file marker
A Ctrl-Z code that marks the logical end of a file.
A)environment
The context within which DOS interfaces with you and with your
commands.
A)error level
A code, set by programs as they conclude processing, that tells
DOS whether an error occurred, and if so, the severity of that
error.
A)expansion cards
Add-on circuit boards through which hardware can increase the
power of the system, such as adding extra memory or a modem.
A)expansion slots
Connectors inside the computer in which expansion cards are
placed so that they tie in directly to the system.
A)extended ASCII codes
ASCII codes between 128 and 255, which usually differ from
computer to computer.
A)extended DOS partition
A hard-disk partition used to exceed the 32 megabyte, single-disk
barrier; it can be divided into logical disk drives.
A)extended memory
Additional physical memory beyond the DOS 1 megabyte addressing
limit.
A)extension
The one to three characters after the period following the base
name in a file specification.
A)external buffer
A device, connected to the computer and another device, that acts
as a buffer.
A)file
A collection of bytes, representing a program or data, organized
into records and stored as a named group on a disk.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
directory
directory tree
path
subdirectory
A)file allocation table (FAT)
A table of sectors stored on a disk, which tells DOS whether a
given sector is good, bad, continued, or the end of a chain of
records.
A)file name
The name of a file on the disk. Usually refers to the base name,
but can include the extension as well.
A)file version
A term that refers to which developmental copy of a software
program is being used or referenced.
A)filter
A program that accepts data as input, processes it in some
manner, and then outputs the data in a different form.
A)fixed disk
IBM's name for a hard disk.
A)floppy diskette
See diskette.
A)flow of control
The order of execution of batch file commands; how the control
flows from one command to another, even when the next command to
be executed is not located sequentially in the file.
A)foreground task
The main program running on your computer, as opposed to the less
visible background task (usually a print-ing job).
A)formatting
The placement of timing marks on a disk to arrange the tracks and
sectors for subsequent reading and writing.
A)fragmentation
A condition in which many different files have been stored in
noncontiguous sectors on a disk.
A)function keys
Special-purpose keys on a keyboard, which can be assigned unique
tasks by DOS or by application programs.
A)global characters
See wildcards.
A)graphics mode
The mode in which all screen pixels on a monitor are addressable
and can be used to generate detailed images. Contrasts with text
mode, which usually allows only 24 lines of 80 characters.
A)hard disk
A rigid platter that stores data faster and at a higher density
than a floppy diskette. Sealed in an airtight compartment to
avoid contaminants that could damage or destroy the disk.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
active partition
head
hardware
A)hardware
The physical components of a computer system.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
active partition
diskette
hard disk
disk drive
A)hardware interrupt
A signal from a device to the computer, indicating that an event
has taken place.
A)head
A disk-drive mechanism that reads data from and writes data to
the disk.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
hard disk
head crash
A)head crash
Occurs when the head hits the disk platter on a hard disk,
physically damaging the disk and the data on it.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
head
A)help file
A file of textual information containing helpful explanations of
commands, modes, and other on-screen tutorial information.
A)hexadecimal
A numbering system in base 16. A single 8-bit byte can be fully
represented as two hexadecimal digits.
A)hidden files
Files whose names do not appear in a directory listing. Usually
refers to DOS' internal system files, but can also refer to
certain files used in copy-protection schemes.
A)high-capacity diskette
A 1.2 megabyte, 5--inch floppy diskette.
A)high-resolution mode
The mode on a video monitor in which all available pixels are
used to provide the most detailed screen image possible. On a
color monitor, this mode reduces the possible range of colors
that can be output.
A)horizontal landscape
When output to a printer is not done in the usual format, but
rather with the wider part of the paper laid out horizontally, as
in a landscape picture.
A)hot key
A key combination used to signal that a memory-resident program
should begin operation.
A)housekeeping
Making sure the directory stays intact and well organized, and
that unnecessary files are deleted.
A)hub
The center hole of a diskette.
A)IF
A conditional statement in a batch file.
A)ink-jet printer
A printer that forms characters by spraying ink in a dot pattern.
See dot-matrix printer.
A)interface
The boundary between two things, such as the computer and a
peripheral.
A)interrupt
A signal sent to the computer from a hardware device, indicating
a request for service or support from the system.
A)keyboard translation table
An internal table, contained in the keyboard driver, that
converts hardware signals from the keyboard into the correct
ASCII codes.
A)key combination
When two or more keys are pressed simultaneously, as in Ctrl-
Scroll Lock or Ctrl-Alt-Del.
A)key redefinition
Assigning a nonstandard value to a key.
A)kilobyte (K)
1024 bytes.
A)laser printer
A printer that produces images (pictures or text) by shining a
laser on a photostatic drum, which picks up toner and then
transfers the image to paper.
A)LCD
Liquid Crystal Display. A method of producing an image using
electrically sensitive crystals suspended in a liquid medium.
A)letter-quality printer
A printer that forms characters that are comparable to those of a
typewriter.
A)line editor
A program that can make textual changes to an ASCII file, but can
only make changes to one line of the file at a time.
A)line feed
When the cursor on a screen moves to the next line, or when the
print head on a printer moves down the paper to the next line.
A)literal
Something that is accepted exactly as it was submitted.
A)lockup
Occurs when the computer will not accept any input and may have
stopped processing. Requires that the computer be warm or cold
booted to resume operating.
A)log file
A separate file, created with the BACKUP command, that keeps
track of the names of all files written to the backup
diskette(s).
A)logging on
Signing onto a remote system, such as a mainframe or
telecommunications service.
A)logical
Something that is defined based on a decision, not by physical
properties.
A)logical drives
Disk drives, created in an extended DOS partition, that do not
physically exist, but DOS operates as if they do. A means for DOS
to access a physical disk that has more than 32 megabytes
available.
A)logical testing
See decision making.
A)machine language
The most fundamental way to program a computer, using
instructions made up entirely of strings of 0sand 1s.
A)macro
A set of commands, often memory-resident. When executed, they
appear to the program executing them as if they were being
entered by you.
A)medium-resolution mode
The mode on a Color Graphics Adapter in which only 320x200 pixels
of resolution are allowed.
A)megabyte (Mb)
1024 kilobytes.
A)memory
The circuitry in a computer that stores information. See also RAM
and ROM.
A)memory-resident
Located in physical memory, as opposed to being stored in a disk
file.
A)menu
A set of choices displayed in tabular format.
A)meta symbols
Special single-character codes used by the PROMPT command to
represent complex actions or sequences to be included in the DOS
prompt.
A)microfloppy diskette
The 3-inch diskette format used in the new PS/2 and many other
computers.
A)modem
A device that transmits digital data in tones over a phone line.
A)monitor
The device used to display images; a display screen.
A)monochrome
Using two colors only: the background and foreground.
A)mouse
A device that moves the screen cursor by means of a hand-held
apparatus moved along a surface such as a desk. The computer can
tell how far and in which direction the mouse is being moved.
A)multitasking
When two or more computing applications are executing
simultaneously.
A)national language-support operations
The DOS 3.3 feature that supports displays and printers, using a
new range of code and character groupings.
A)network
Several computers, connected together, that can share common data
files and peripheral devices.
A)nibble
Four bits, or half a byte.
A)octal
A numbering system in base 8.
A)operating system
See DOS.
A)overlay files
Files containing additional command and control information for
sophisticated and complex programs. An overlay file is usually
too large to fit into memory along with the main .EXE or .COM
file.
A)overwriting
Typing new data over what is already there.
A)parallel communications
Data transmission in which several bits can be transferred or
processed at one time.
A)parameter
An extra bit of information, specified with a command, that
determines how the command executes.
A)parity bit
The bit, added to the end of a stream of data bits, that makes
the total of the data bits and the parity bits odd or even.
A)partition
The section of a hard disk that contains an operating system.
There can be at most four partitions on one hard disk.
A)Pascal
A programming language used mainly in computer science.
A)password
A sequence of characters that allows entry into a restricted
system or program.
A)path
The list of disks and directories that DOS will search through to
find a command file ending in .COM, .BAT, or .EXE.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
directory
directory tree
file
subdirectory
A)peripheral
Any physical device connected to the computer.
A)piping
Redirecting the input or output of one program or command to
another program or command.
A)pixel
The smallest unit of display on a video monitor- -in short, a
dot- -that can be illuminated to create text or graphics images.
A)platter
The rigid disk used in a hard disk drive.
A)plotter
A device that draws data on paper with a mechanical arm.
A)port
A doorway through which the computer can access external devices.
A)primary DOS partition
Up to the first 32 megabytes of a hard disk. Contains the boot
record and other DOS information files.
A)printer
A device that outputs data onto paper using pins (dot matrix), a
daisy wheel, ink jets, laser imaging, and so on.
A)public domain
Something not copyrighted or patented. Public domain software can
be used and copied without infringing on anyone's rights.
A)queue
A series of files waiting in line to be printed.
A)RAM
Random Access Memory. The part of the computer's memory to which
you have access; stores programs and data while the computer is
on.
A)RAM disk
An area of RAM that acts as if it were a disk drive. All data in
this area of memory is lost when the computer is turned off or
warm booted. Also known as a virtual disk.
A)range
A contiguous series of values (minimum to maximum, first to last,
and so on).
A)read-after-write verification
An extra level of validity checking, invoked with the VERIFY
command or the /V switch. Rereads data after writing it to disk,
comparing the written data to the original information.
A)read-only status
Indicates that a file cannot be updated but can be read.
A)read/write bit
The bit in a file specification that indicates whether a file can
accept changes or deletions, or can only be accessed for reading.
A)redirection
Causing output from one program or device to be routed to another
program or device.
A)REM statement
A line in a BASIC program containing remarks or comments for
program explanation or clarification.
A)reserved names
Specific words, in a programming language or operating system,
that should not be used in any other application context.
A)resident commands
Commands located in random access memory.
A)resource allocation
Making system facilities available to individual users or
programs.
A)reverse video
Black letters on a white background.
A)ROM
Read-Only Memory. The section of memory that you can only read
from. This contains the basic computer operating system and
system routines.
A)root directory
The first directory on any disk.
A)scan code
The hardware code representing a key pressed on a keyboard.
Converted by a keyboard driver into an ASCII code for use by DOS
and application programs.
A)scrolling
What the screen does when you're at the bottom of it and press
Return- -all of the lines roll up.
A)secondary command processor
A second copy of COMMAND.COM, invoked either to run a batch file
or to provide a new context for subsequent DOS commands.
A)sector
A division of a disk track; usually, 512 bytes.
A)serial communications
Data transmission in which data is transferred and processed one
bit at a time. Also known as asynchronous communications.
A)shareware
Public domain software. See also public domain.
A)snapshot program
A program used in debugging to store the status of system or
application program variables.
A)software
The programs and instruction sets that operate the computer.
A)software interrupt
A signal from a software program that calls up a routine that is
resident in the computer's basic programming. Also, a software
signal to the computer that the software program has finished,
has a problem, and so on.
A)source
The location containing the original data, files, or other
information to be used in a DOS command.
A)spooling
Simultaneous Peripheral Operations On-Line. Using a high-speed
disk to store input to or output from low-speed peripheral
devices while the CPU does other tasks.
A)spreadsheet program
An electronic version of an accountant's spreadsheet; when one
value changes, all other values based on that value are updated
instantly.
A)start bit
The bit sent at the beginning of a data stream to indicate that
data bits follow.
A)stop bit
The bit sent after the data bits, indicating that no more data
bits follow.
A)string
A series of characters.
A)subcommands
Several special commands used only within batch files.
A)subdirectory
A directory contained within another directory or subdirectory.
Technically, all directories other than the root directory are
subdirectories.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
directory
directory tree
file
path
A)switch
A parameter included in DOS commands, usually preceded by the
slash (/) symbol, that clarifies or modifies the action of the
command.
A)synchronization
The coordination of a sending and receiving device, so that both
simultaneously send and receive data at the same rate.
A)system disk
A disk containing the necessary DOS files for system booting.
A)text mode
The mode in which standard characters can be displayed on a
monitor.
A)time slice
The smallest unit of time managed and assigned by the operating
system to programs and other processing activities.
A)toggle
A switch or command that reverses a value from off to on, or from
on to off.
A)track
A circular stream of data on the disk. Similar to a track on a
record, only not spiraling.
A)transient command
A command whose procedures are read from the disk into memory,
executed from memory, and then erased from memory when finished.
A)utility
A supplemental routine or program designed to carry out a
specific operation, usually to modify the system environment or
perform housekeeping tasks.
A)variable parameter
A named element, following a command, that acts as a placeholder;
when you issue the command, you replace the variable parameter
with the actual value you want to use.
A)verbose listing
A listing of all files and subdirectories contained on the disk
and path specified in the command. Activated by the CHKDSK
command with the /V switch.
A)vertical portrait
The conventional 8-by-11-inch output for printed information,
with the long side of the paper positioned vertically.
A)virtual disk
See RAM disk.
A)volume label
A name, consisting of up to 11 characters, that can be assigned
to any disk during a FORMAT operation or after formatting with
the LABEL command.
A)warm booting
Resetting the computer using the Ctrl-Alt-Del key combination.
See bootstrapping.
A)wide directory listing
An alternate output format that lists four columns of file names.
A)wildcards
Characters used to represent any other characters. In DOS, * and
? are the only wildcard symbols.
A)word processor
A computerized typewriter. Allows the correction and reformatting
of documents before they are printed.
A)write-protection
Giving a disk read-only status by covering the write-protect
notch.
A)Character Sets
Just as you use an alphabet and a decimal numbering system,
the computer uses its own character and numbering system. DOS
maintains, in memory, all of the characters of the English
alphabet, including numbers and symbols, as well as some foreign
symbols (such as accented vowels). This group of symbols is
called a character set. By changing the symbols in this set, you
can obtain completely new character sets. This is especially
useful for people living in other countries, who have less daily
need of U.S. standard characters and who would rather work with
their own characters.
ASCII Codes
A character is any letter, number, punctuation symbol, or
graphics symbol. In other words, it is anything that can be
displayed on a video screen or printed on a printer.
Each character in a character set has a number assigned to
it, which is how the computer refers to the various characters in
the set. For example, code 65 refers to a capital A, and code 97
refers to a lowercase a. These codes are called ASCII codes
(pronounced ``ask-ee codes''); ASCII stands for American Standard
Code for Information Interchange.
Codes 0 through 31 are used as control codes. Displaying one
of these codes will cause something to happen instead of causing
a symbol to be displayed. For example, displaying code 7 will
result in the computer's bell or beeper being sounded. Displaying
code 13 will result in a carriage return.
Codes 32 through 127 are ASCII character codes for numbers,
letters, and all punctuation marks and symbols. Codes 128 through
255, known as extended ASCII codes, vary from computer to
computer. They usually comprise foreign characters, Greek and
mathematical symbols, and graphics characters. (Graphics
characters consist of small lines and curves that can be used to
create geometric patterns.)
DOS 3.3 has several available ASCII tables, called code
pages. The most common is the standard U.S. code page; the next
most common is the Multilingual code page.
Mapping Character Sets
Any device that displays characters has a device driver that
literally drives, or controls, the device. When the computer
tells a printer to print the letter A, DOS sends the code 65 to
the printer driver, which converts the 65 into a series of
control codes that will print the A.
For the sake of consistency, computers, printers, and
displays all have the same character sets and coding system for
ASCII codes 32 through 127. This ensures that when you press a
key, the desired character will be displayed, and the same
character will be printed by your printer.
The process of matching ASCII codes against characters in a
character set is called mapping.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Numbering Systems
A)Numbering Systems
Computers use a variety of numbering systems to operate. The
most basic numbering system is the binary system, in which there
are only two digits, 0 and 1. The digital circuitry used in
computers operates by using small voltages that turn magnetic
bits on or off. Therefore, 0 and 1 are used to represent the two
states of off and on, respectively.
Counting in binary is not difficult, but it does require
some adjustment from the standard decimal-numbering scheme. The
progression of numbers and their matching decimal conversions are
shown in the table below.
----------------------------------------------------------------
Binary Decimal
0 0
1 1
10 2
11 3
100 4
101 5
110 6
111 7
1000 8
1001 9
1010 10
----------------------------------------------------------------
The general rule for converting numbers from binary to
decimal is to multiply the number in every binary number column
by 2 raised to the column-number power. You count column numbers
from the right, starting with 0. For the binary number 1101, for
example, you would obtain
(1x20)+(0x21)+(1x22)+(1x23)
where any number to the 0 power (20 in this case) is defined as
equal to 1. This is called counting in base 2.
The decimal system counts in base 10. Using the same method
of converting binary numbers, you can see that breaking down the
decimal number 2014 into its component parts works like this:
(4x100)+(1x101)+(0x102)+(2x103)
=4+10+000+2000
=2014
Another numbering system is called octal, or base 8. This system
has only eight digits, 0 to 7. The octal number 701 is converted
to base 10 (decimal) by the following computation:
(1x80)+(0x81)+(7x82)
=1+0+448
=449
The last major numbering system in computers is called
hexadecimal, which counts in base 16. This system has 16 digits
in it: 0 to 9 and A to F, which form the counting sequence
0123456789ABCDEF. To count in this system, you use the same
method you use for other numbering systems. The hexadecimal
number BA7 translates to decimal as
(7x160)+x161)+(Bx162)
which is equal to
7+(10x161)+(11x162)
which is also equal to
7+160+2816
=2983
The table below demonstrates how to count in hexadecimal.
----------------------------------------------------------------
Hexadecimal Decimal
0 0
. .
. .
9 9
A 10
B 11
. .
. .
F 15
10 16
. .
. .
1A 26
----------------------------------------------------------------
Hexadecimal notation is convenient for byte values because a
hexadecimal digit is equivalent to 4 (24=16) binary digits
(called a nibble) and there are 8 bits (28=256-character set) in
a byte. A byte can therefore be represented by two hexadecimal
digits.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Character Sets
A)AUTOEXEC.BAT File
You can create a special batch file, named AUTOEXEC.BAT,
which contains all of the DOS commands that you wish to have
invoked every time you start your computer. The command
statements in the AUTOEXEC.BAT file often include such DOS
commands as DATE, TIME, PROMPT, PATH, and SET. These can also
include commands that execute special RAM-resident programs such
as Lightning or SideKick or a menu program of your own design.
Such a program would allow you to start up specific application
programs available on your PC- -dBASE III PLUS, Lotus 1-2-3, or
WordPerfect, for example.
Every time you start your computer, DOS checks for the
presence of the AUTOEXEC.BAT file on either the disk in drive A
if you are using a two-floppy disk system, or in the root
directory of drive C if you are using a hard disk system. If DOS
locates such a file, it automatically executes the statements it
contains upon completion of the boot sequence.
When you create the AUTOEXEC.BAT file, remember to include
the DATE and TIME commands along with the other commands you wish
executed each time you start the computer. (If your computer is
equipped with a clock/calendar card, enter the appropriate
commands to have the date and time read.) If you do not add
these commands, DOS will no longer prompt you for the current
date and time as part of the start-up procedure and, as a result,
the files you create with your application programs will not be
stamped with the correct date and time.
Consider the following example created with the COPY command
and containing a sampling of DOS commands typically used in the
AUTOEXEC.BAT file:
COPY CON AUTOEXEC.BAT
DATE
TIME
PROMPT $p$g
PATH = C:\;C:\DOS;C:\BATCH
Ctrl-Z
After creating this AUTOEXEC.BAT file, when you start your
computer DOS will first prompt you to update the date and time.
Once you have responded to these commands, DOS changes the prompt
so that it always displays the current directory, and then sets
the path so that it will check the root, \DOS, and \BAT
directories for any command that you enter, regardless of which
directory you are in at the time.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
PATH Command
PRINT Command
SET Command
A)Displaying of Text with Batch Files
The batch files that you create can contain messages that
are displayed to alert the user to the underlying purpose of the
batch file or to prompt the user to take a particular step- -such
as changing data disks- -during a pause in the execution of a
command. You can also add messages that are displayed as part of
the ECHO command, which controls whether the command statements
entered in the batch file are displayed to the user as they are
executed by DOS.
REM Command
One way to have text displayed on the screen during the
execution of a batch command is with the use of the REM (remark)
command
REM remark
where
remark Specifies the comment to be added to a
batch file.
DOS will not try to execute a REM command, although it will
display REM and the text that follows it on the screen unless it
has previously executed an ECHO OFF statement (see Using the ECHO
Command, which follows).
You can use the REM command to add messages to the batch
file that help make clear its function and procedure. If you wish
to add a nonprinting comment whose purpose is to document the use
of particular commands in your batch file but that is never to be
displayed on the screen to the user, you simply preface the text
of this type of comment with a colon, as in:
:Start backup
Comments prefaced with a colon will appear when you use the TYPE
command to display the contents of the batch file on your screen,
or when you use the COPY or PRINT command to obtain a printout.
PAUSE
You can also have messages displayed on the screen during a
pause in the execution of batch file commands. The syntax for the
PAUSE command is
PAUSE [message]
where
[message] Specifies the message you want to have
displayed on the screen when PAUSE is
invoked.
When DOS encounters a PAUSE statement, it pauses the
execution of the commands in the batch file and displays your
message on the screen, followed by its own message
Strike a key when ready. . .
on the line below. If you enter the PAUSE command without any
message text, you will see only this DOS message instructing you
to strike a key to continue the execution of the batch file.
When you use the PAUSE command, the word PAUSE is always
displayed on the screen along with the message you have entered
(just as when using the REM command). If the batch file has
executed an ECHO OFF command before it encounters your PAUSE
command, neither the word PAUSE nor the text of your message will
be displayed on the screen. Only the DOS message about striking a
key to continue will be visible (see Using the ECHO batch file command,
which follows).
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
PRINT Command
TYPE Command
A)ECHO
When DOS executes the commands in a batch file, it can
display each command statement on the screen as it is executed.
You can enter the ECHO command in the batch file to control
whether the command statements are displayed. The syntax is
ECHO [OFF]
or
ECHO [ON]
where
OFF Suppresses the display of command
statements during the execution.
ON Used if you wish to have subsequent
commands displayed on the screen during
the execution of the batch file.
Note that if you enter the ECHO command in a batch file (or
at the DOS prompt) without using either the ON or OFF parameters,
DOS responds by displaying the current state of the ECHO command.
You will see either ECHO is on or ECHO is off.
If you are using DOS 3.3, you can also suppress the display
of a command statement in the batch file by prefacing it with the
@ symbol. For example, entering
@VERIFY ON
will prevent the VERIFY ON command from being displayed. However,
each command statement that you wish to suppress must be prefaced
by an @ symbol. If you use @ECHO OFF, the ECHO OFF command as
well as all subsequent statements are automatically suppressed
until an ECHO ON command occurs.
When ECHO is off, only the display of the command statements
in the batch file will be suppressed. DOS will continue to
display any message that is normally shown after a particular
commandhas been processed. For instance, if your batch file
contains the statement
ECHO OFF
followed by a command to copy a particular file from one
directory to another, you will still see the DOS message
1 File(s) copied
although you will not see the contents of the COPY command itself
on the line above it. Note that you can often get rid of these
messages by redirecting output to NUL:
COPY *.* A: NUL
You can use the ECHO command to display messages to the
user. First, set ECHO to off. Then, enter an ECHO command
followed by at least one space and the text of your message. When
you use the ECHO command in this way, only your message is
displayed onthe screen. DOS does not include the command word
(ECHO) as it does when displaying messages with the REM or PAUSE
commands.
For example, you could have your batch file display a prompt
to insert a data disk in drive A by using the ECHO and PAUSE
commands as follows:
ECHO OFF
.
.
.
ECHO Insert data disk in drive A
PAUSE
When the batch file executes these last two commands, you see
only
Insert data disk in drive A
Strike a key when ready. . .
on the screen. ECHO does not appear along with the prompt
message, but the separate PAUSE command causes the Strike a key
when ready. . . message to be displayed.
When you use the ECHO command to display messages and
prompts, be sure that it is preceded by an ECHO OFF statement (or
an @ symbol if you are using DOS 3.3) in the batch file.
Otherwise, you will see the ECHO command statement containing the
message as well as the message itself when the batch file is run.
Note that the use of the REM, PAUSE, and ECHO commands to
display on-screen messages slows down the execution of the batch
file appreciably. If you need to include extensive instructions
for a particular batch file, use the TYPE command to have them
displayed on the screen.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
COPY Command
A)Replaceable Parameters in Batch Files
You can define parameters (or arguments) that are passed to
particular command statements in a batch file with the use of
replaceable or dummy parameters. This makes the batch file more
flexible because you get to define the arguments to be passed to
the command statements at the time you execute the batch file.
You can define up to ten different replaceable parameters to
be used in a batch file. Each one is given a number between 0 and
9 preceded by the percent sign, as in %1, %2, and so on. Note,
however, that the replaceable parameter %0 represents a special
case: it is always replaced with the file name of the batch file.
The other nine replaceable parameters have no such fixed
replacements: you can make then stand for DOS commands, file
names, parts of file names (such as extensions), directory paths,
and the like. For instance, you could use replaceable parameters
to create a batch file named WHEREIS.BAT that locates a
particular file for you. This batch file contains only a single
command statement using the replaceable argument, as follows:
CHKDSK /V | FIND ``%1''
The CHKDSK command with the /V parameter lists all of the files
and subdirectories for the current directory and pipes this
information to the FIND command.
The FIND command contains the replaceable parameter %1. When
you execute the WHEREIS.BAT file, you enter the filename you wish
to locate along with the batch file name. To locatea file called
LOAN.FRM on the hard disk, you run the batch fileby entering
WHEREIS LOAN.FRM
DOS will then execute WHEREIS.BAT as though you had entered
CHKDSK /V|FIND ``LOAN.FRM''
as the command statement. If this file is located in C:\WP\FORMS,
DOS will respond by displaying
C:\WP\FORMS\LOAN.FRM
As you can see, you can use this same batch file to search for
any file or group of files, simply by entering a different file
name at the time you execute it.
In complex batch files, you may find that ten replaceable
parameters are not sufficient. In such a case, you can use the
SHIFT command. SHIFT discards each argument after it has been
acted upon, replacing it with the next argument so that after the
first argument is processed, the second becomes the first, the
third the second, and so on. After you use the SHIFT command, the
0% argument is never acted upon, since the %n argument becomes
the %(n--1) argument. Note that SHIFT is useful in loops, which
are described later in this appendix.
Passing Arguments from the Environment
As noted in the SET reference entry, you can specify a set
of strings that the batch files can refer to. For example, if you
enter the SET command
SET REPORT = YREND
and have previously entered the following command line in a batch
file
COPY %REPORT%.WK1 A:
the batch file will copy the file named YREND.WK1 to the floppy
disk in drive A when the batch file is run.
Note that the replaceable argument in the batch file command
line is enclosed in a pair of percent signs (%). This indicates
to DOS that the argument is to be taken from the environment.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
COPY Command
FIND Command
A)Loops in Batch Files
There are several methods for creating loops in batch files.
If you want the entire batch file to repeat, you can use the %0
replaceable parameter as the last command. You will recall that
%0 is always replaced with the file name of the batch file. When
you add it asthe last statement in a batch file, it causes all of
the commands in thefile to be repeated. For example, if you
create a batch file namedDIRA.BAT that contains the command
statements
ECHO OFF
ECHO Insert new disk in drive A
PAUSE
DIR A:/p
%0
the file will repeatedly prompt you to insert a different disk in
drive A and then give you a directory listing of all of the files
it contains when you press a key to continue. This batch file
will continue to repeat until you press Ctrl-C or Ctrl-Break to
terminate it.
The FOR Loop
To repeat a command within a batch file for a specific
number of cases, you use the FOR command. The syntax for the FOR
command is
FOR %%variable IN (set) DO command
where
command Specifies the command to be executed for
each member listed in the (set)
argument, in the order in which these
members are entered. The command
argument can consist of only a single
command, which can be another batch file
command (except for the FOR command), an
executable program, batch file, or DOS
command. Note that you cannot nest FOR
batch commands, which is why the command
argument cannot contain another FOR
command statement.
set Specifies files to be operated upon.
variable Specifies the variable to be operated on
by the command. Notice that a double
percent sign is entered before the
variable (usually, though not
necessarily, a single letter) to
distinguish it from a replaceable
parameter.
Consider this example using the FOR command:
FOR %%A IN (1985.WK1 1986.WK1 1987.WK1)
DO COPY %%A %2
In this batch file, the FOR command statement copies each of the
three worksheet files listed in the (set) argument to the
directory path entered when the batch file is run by passing it
to the %2 replaceable parameter. Notice that the command argument
in this example is actually COPY %%A, instead of just COPY.
The GOTO Command
You can also cause a batch file to execute (and sometimes
repeat) a group of command statements in the file beginning at a
specific point. To do this, you use the GOTO batch command. You
indicate where in the batch file the commands are to be executed
(or repeated) by using a label.
The syntax of the GOTO command is
GOTO [:]label
where
label Specifies a character string of up to
eight alphanumeric characters, and is
not case-sensitive. By convention,
alphabetic characters are entered in
lowercase and the label name is prefaced
by a colon. Note that the colon is
mandatory before the actual label, but
optional before the argument in the
GOTO. The label, however, cannot contain
a period (.).
When you use the GOTO command, DOS executes all of the
command statements listed below the label until it reaches the
end of the batch file or another GOTO statement telling it to
begin reprocessing the commands or to process a new set of
commands beneath another label.
Looping with the GOTO command can be illustrated by the
following generalized form:
:label
command%1
.
.
.
command%n
SHIFT
GOTO :label
Assuming that the commands listed below the :label contain
replaceable parameters, with the use of the SHIFT batch command,
this loop would be executed indefinitely (until you terminated
the batch file by pressing Ctrl-C or Ctrl-Break).
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
A)Conditional Processing
The endless loop illustrated above is of limited use in
batch files. It is much more common to use the GOTO command with
conditional statements. That way, the commmands listed beneath
the label are executed only when the condition is true. Using the
GOTO command with conditions allows you to create batch files
that branch according to the result of the condition.
In addition to using conditional processing to branch, you
can also have command statements executed only when there is
equivalency between two items or if a particular file exists.
The IF Command
The batch IF command is used to allow conditional execution
of command statements. The syntax of the IF command is as
follows:
IF [NOT] condition command
If you wish to have branching occur as a result of the outcome of
the condition, use this form:
IF [NOT] condition GOTO [:]label
There is no ELSE command in the batch file command
vocabulary. If you wish to have the program branch to one set of
commands if the condition is true and another if it is false, use
this form:
IF condition GOTO [:]labela
GOTO [:]labelb
If the condition is true, execution jumps to the commands beneath
label a. If it is false, it jumps to those beneath label b. Note
that you do not have to use the second GOTO statement if the
commands to be executed when the condition is false follow the IF
statement directly.
Testing for Equivalence
The condition argument in an IF command can test for
equivalence between two items. If they are found to be equivalent
(that is, identical in terms of characters and case), then the
command statement listed in the command argument is executed.
When you test for equivalence, you use a double equal sign. The
syntax is as follows:
IF string1==string2 command
Note that strings are case-sensitive.
For example, you could enter the following IF command:
IF %1==December GOTO :endofyr
If you execute this batch file and enter December as the first
replaceable parameter, the batch file will jump to the label
:endofyr and execute the commands that are listed beneath it.
Testing for the Existence of a File
You test for the existence of a particular file as the
condition argument of the IF command. The syntax for this use is
as follows:
IF EXIST [d:][path]filename command
The options are as follows:
command Specifies a command to be executed
only when the file entered for the
d:path filename argument is found
on the drive/directory indicated
(if these parameters are omitted,
then in the current directory).
d:pathfilename Specifies the file to be operated
on.
For example, you might have this IF command statement in a
batch file:
IF EXIST 4QTRTOTL GOTO :yrend
The commands beneath the :yrend label are executed only if DOS
locates the file named 4QTRTOTL in the current directory. If this
file is not found, this GOTO statement is ignored.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
Subroutines for Batch Files
A)Chaining of Batch Files
You can chain batch files by adding the name of the second
batch file to be executed as the last statement in the command
statements of the first batch file. Do not confuse chaining batch
files with calling a new batch file as a subroutine. When
chaining batch files, control does not return to the first batch
file as when using subroutines (see the section on Using
Subroutines, which follows). Because of this, reference to the
second batch file must be entered as the last command statement
in the first batch file. If it is not, the commands below this
reference in the first file will never be executed.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Subroutines for Batch Files
A)Subroutines for Batch Files
To execute a second batch file as a subroutine (that is,
have control returned to the first batch file upon execution of
all command statements in the second file), you must load a
second copy of the command processor, using the COMMAND command.
The syntax is
COMMAND /C batch
where
/C Tells DOS that this a secondary copy of
the command processor.
batch Specifies the batch file you wish to
call as a subroutine.
To have control return to the first batch file and to have
the secondary copy of the command processor unloaded, the EXIT
command must be the last statement in the batch file used as a
subroutine. If you do not place EXIT as the last command
statement in the called batch file, control will not return to
the calling batch file and the secondary copy of the command
processor will continue to run.
Using The CALL Command
DOS 3.3 has added a CALL command that allows you to call a
second batch file as a subroutine (that is, execute the commands
in a second batch file without terminating the first batch file).
This command can be used in place of the COMMAND and EXIT
commands.
The syntax of the CALL command is
CALL [d:][path]filename
where
d:pathfilename Specifies the name of the
batch file to be called. When
entering this file name, do
not include the .BAT file
extension.
You can use the CALL command to call its own batch file.
However, you need to provide a method whereby the batch file is
eventually terminated.
------------------------------------------------------------------
[For related topics, press R]
SEE ALSO
Batch Files
Creation of Batch Files
AUTOEXEC.BAT File
Displaying of Text with Batch Files
ECHO batch file command
Replaceable Parameters in Batch Files
Loops in Batch Files
Conditional Processing
Chaining of Batch Files
COMMAND Command
| file: /Techref/dos/bats.htm, 137KB, , updated: 2007/1/25 09:55, local time: 2024/11/22 19:11,
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