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GNU Info (make.info)Wildcard FunctionThe Function `wildcard' ----------------------- Wildcard expansion happens automatically in rules. But wildcard expansion does not normally take place when a variable is set, or inside the arguments of a function. If you want to do wildcard expansion in such places, you need to use the `wildcard' function, like this: $(wildcard PATTERN...) This string, used anywhere in a makefile, is replaced by a space-separated list of names of existing files that match one of the given file name patterns. If no existing file name matches a pattern, then that pattern is omitted from the output of the `wildcard' function. Note that this is different from how unmatched wildcards behave in rules, where they are used verbatim rather than ignored (Note: Wildcard Pitfall). One use of the `wildcard' function is to get a list of all the C source files in a directory, like this: $(wildcard *.c) We can change the list of C source files into a list of object files by replacing the `.c' suffix with `.o' in the result, like this: $(patsubst %.c,%.o,$(wildcard *.c)) (Here we have used another function, `patsubst'. Note: Functions for String Substitution and Analysis.) Thus, a makefile to compile all C source files in the directory and then link them together could be written as follows: objects := $(patsubst %.c,%.o,$(wildcard *.c)) foo : $(objects) cc -o foo $(objects) (This takes advantage of the implicit rule for compiling C programs, so there is no need to write explicit rules for compiling the files. Note: The Two Flavors of Variables, for an explanation of `:=', which is a variant of `='.) automatically generated by info2www version 1.2.2.9 |