Question

I’m trying to create a target which matches multiple directories, but no files. Is there any way to flag the target explicitly as being a directory?

For example:

output/%:
    mkdir -p $@

matches files as well, which is definitely not something I want.

Basically, I have many variables which contain directory names which need to be created if they don’t exist, and the best way to do that, as far as I’ve found is this:

all: directories other_stuff

directories: $(dir1) $(dir2) ...

$(dir1):
    mkdir -p $@
$(dir2):
    mkdir -p $@
...

So, I’m OK with repeating the directory variables as dependencies for the directories target, but creating targets for each directory I add seems overkill and hard to maintain.

Answer 1

Here is one possibility:

DIR_LIST = $(dir1) $(dir2) $(dir3)

.PHONY: all
all: directories other_stuff

.PHONY: directories  # Note: you should be marking this as phony
directories: $(DIR_LIST)

$(DIR_LIST):
    mkdir -p $@

See http://www.gnu.org/software/make/manual/make.html#Multiple-Targets.