Define an NMAKE macro

An NMAKE macro is defined by using this syntax:

macro_name=string

The macro_name is a case-sensitive combination of letters, digits, and underscores (_) up to 1,024 characters long. The macro_name can contain an invoked macro. If macro_name consists entirely of an invoked macro, the macro being invoked can't be null or undefined.

The string can be any sequence of zero or more characters. A null string contains zero characters or only spaces or tabs. The string can contain a macro invocation.

Special characters in macros

A number sign (#) after a definition specifies a comment. To specify a literal number sign in a macro, use a caret (^) to escape it, as in ^#.

A dollar sign ($) specifies a macro invocation. To specify a literal $, use $$.

To extend a definition to a new line, end the line with a backslash (\). When the macro is invoked, the backslash and following newline character is replaced with a space. To specify a literal backslash at the end of the line, precede it with a caret (^) escape, or follow it with a comment specifier (#).

To specify a literal newline character, end the line with a caret (^) escape, as in this example:

CMDS = cls^
dir

Null and undefined macros

Both null and undefined macros expand to null strings, but a macro defined as a null string is considered defined in preprocessing expressions. To define a macro as a null string, specify no characters except spaces or tabs after the equal sign (=) in a command line or command file, and enclose the null string or definition in double quotation marks (" "). To undefine a macro, use !UNDEF. For more information, see Makefile preprocessing directives.

Where to define macros

Define macros in a command line, command file, makefile, or the Tools.ini file.

In a makefile or the Tools.ini file, each macro definition must appear on a separate line and can't start with a space or tab. Spaces or tabs around the equal sign are ignored. All string characters are literal, including surrounding quotation marks and embedded spaces.

In a command line or command file, spaces and tabs delimit arguments and can't surround the equal sign. If string has embedded spaces or tabs, enclose either the string itself or the entire macro in double quotation marks (" ").

Precedence in macro definitions

If a macro has multiple definitions, NMAKE uses the highest-precedence definition. The following list shows the order of precedence, from highest to lowest:

1. A macro defined on the command line

2. A macro defined in a makefile or include file

3. An inherited environment-variable macro

4. A macro defined in the Tools.ini file

5. A predefined macro, such as CC and AS

Use /E to cause macros inherited from environment variables to override makefile macros with the same name. Use !UNDEF to override a command line.

See also

Macros and NMAKE