IF--Examples
 
The following example tests for the existence of a directory. The IF command
cannot be used to test directly for a directory, but the null (NUL) device
does exist in every directory on the hard drive. Therefore, you can test for
the null device to determine whether a directory exists on the hard drive.
 
    if exist c:\mydir\nul goto process
 
The following example displays the message "Can't find data file" if MS-DOS
cannot find the file PRODUCT.DAT:
 
    if not exist product.dat echo Can't find data file
 
When a program stops, it returns an exit code to MS-DOS. For example, a
value of 0 is typically used to indicate that a program was successfully
executed. The ERRORLEVEL parameter lets you use exit codes as conditions.
 
The following example displays an error message if an error occurs during
formatting of the disk in drive A. If no error occurs, the error message is
skipped.
 
    :begin
    echo off
    format a: /s
    if not errorlevel 1 goto end
    echo An error occurred during formatting.
    :end
    echo End of batch program.
 
For another example of how the ERRORLEVEL parameter is used, see the
<CHOICE> command.