Some application programs add extensions to the files you create. These application programs use the extension to determine whether it is a compatible data file. Avoid using the same extensions as your application programs. Also, do not use uppercase and lowercase letters to distinguish between files. MS-DOS does not recognize the difference and displays all filenames in uppercase.

Certain extensions are reserved for program files. You must not use these extensions for your data files. The reserved extensions are

.COM, .EXE, and .BAT Files with these extensions are also sometimes called executable files.

The .BAT extension denotes a particular kind of executable file called a batch file. Batch files can be used to automate sequences of MS-DOS instructions. Even if you are not a programmer, you may want to create some batch files to assist you in your work. A particularly useful kind of batch file, called an autoexecute batch file (or “AUTOEXEC” file ) is discussed later in this chapter.

Copying Files

You can use the COPY command to copy individual files or groups of files. COPY is an internal command; you can use it any time you see the MS-DOS command prompt. You can also use the XCOPY command to copy individual files or groups of files. XCOPY, an external command, is more versatile than COPY. For details about XCOPY, see your MS-DOS Reference Manual.

You can use the COPY command to copy files in several ways:

•You can copy individual files from a diskette or the hard disk to a diskette or hard disk

•You can copy a group of files using wildcard characters

•You can copy one or more files and give them new names

•You can combine or merge files into one file.

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