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GNU Info (make.info)DefiningDefining 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 canned sequences of commands (*note Defining Canned Command Sequences: Sequences.). 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 (Note: 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. 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). 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. Note: 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 Note: The `override' Directive. automatically generated by info2www version 1.2.2.9 |