GNU `make'

Node:Defining, Next:Environment, Previous:Override Directive, Up:Using Variables

### Defining Variables Verbatim

Another way to set the value of a variable is to use the `define` directive. This directive has an unusual syntax which allows newline characters to be included in the value, which is convenient for defining both canned sequences of commands (see Defining Canned Command Sequences), and also sections of makefile syntax to use with `eval` (see Eval Function).

The `define` directive is followed on the same line by the name of the variable and nothing more. The value to give the variable appears on the following lines. The end of the value is marked by a line containing just the word `endef`. Aside from this difference in syntax, `define` works just like `=`: it creates a recursively-expanded variable (see The Two Flavors of Variables). The variable name may contain function and variable references, which are expanded when the directive is read to find the actual variable name to use.

You may nest `define` directives: `make` will keep track of nested directives and report an error if they are not all properly closed with `endef`. Note that lines beginning with tab characters are considered part of a command script, so any `define` or `endef` strings appearing on such a line will not be considered `make` operators.

         define two-lines
         echo foo
         echo $(bar)
         endef

The value in an ordinary assignment cannot contain a newline; but the newlines that separate the lines of the value in a `define` become part of the variable's value (except for the final newline which precedes the `endef` and is not considered part of the value).

When used in a command script, the previous example is functionally equivalent to this:

         two-lines = echo foo; echo $(bar)

since two commands separated by semicolon behave much like two separate shell commands. However, note that using two separate lines means `make` will invoke the shell twice, running an independent subshell for each line. See Command Execution.

If you want variable definitions made with `define` to take precedence over command-line variable definitions, you can use the `override` directive together with `define`:

         override define two-lines
         foo
         $(bar)
         endef

See The `override` Directive.