MS DOS Command: IF

Reference from Microsoft MS-DOS cmd help

Description

Performs conditional processing in batch programs. If the condition specified by an IF command is true, MS-DOS carries out the command that follows the condition. If the condition is false, MS-DOS ignores the command. You can use this command only in batch programs.

Syntax

Parameters

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.