Makefile: Difference between revisions
→Basics: Added a word on := vs. =
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(A quick review as I start to reference this tutorial from elsewhere.) |
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A definition declares a variable, and assigns a value to it. Its overall syntax is ''VARIABLE := Value''.
'''Note:''' Frequently, you will see declarations with "=" instead of ":=". That is usually a typo; such a variable declaration will result in the assignment being evaluated ''every time the variable is used''. Unless you know exactly what you are doing, use ":=" for variable declarations.
A rule defines a ''target'', 0..n ''dependencies'', and 0..n ''commands''. The general idea is that ''make'' checks if the target (file) is there; if it isn't, or any of the dependencies is newer than the target, the commands are executed. The general syntax is:
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