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GNU Info (make.info)Target-specificTarget-specific Variable Values =============================== Variable values in `make' are usually global; that is, they are the same regardless of where they are evaluated (unless they're reset, of course). One exception to that is automatic variables (Note: Automatic Variables.). The other exception is "target-specific variable values". This feature allows you to define different values for the same variable, based on the target that `make' is currently building. As with automatic variables, these values are only available within the context of a target's command script (and in other target-specific assignments). Set a target-specific variable value like this: TARGET ... : VARIABLE-ASSIGNMENT or like this: TARGET ... : override VARIABLE-ASSIGNMENT Multiple TARGET values create a target-specific variable value for each member of the target list individually. The VARIABLE-ASSIGNMENT can be any valid form of assignment; recursive (`='), static (`:='), appending (`+='), or conditional (`?='). All variables that appear within the VARIABLE-ASSIGNMENT are evaluated within the context of the target: thus, any previously-defined target-specific variable values will be in effect. Note that this variable is actually distinct from any "global" value: the two variables do not have to have the same flavor (recursive vs. static). Target-specific variables have the same priority as any other makefile variable. Variables provided on the command-line (and in the environment if the `-e' option is in force) will take precedence. Specifying the `override' directive will allow the target-specific variable value to be preferred. There is one more special feature of target-specific variables: when you define a target-specific variable, that variable value is also in effect for all prerequisites of this target (unless those prerequisites override it with their own target-specific variable value). So, for example, a statement like this: prog : CFLAGS = -g prog : prog.o foo.o bar.o will set `CFLAGS' to `-g' in the command script for `prog', but it will also set `CFLAGS' to `-g' in the command scripts that create `prog.o', `foo.o', and `bar.o', and any command scripts which create their prerequisites. automatically generated by info2www version 1.2.2.9 |