Makefile does not find target

I have the following Makefile, but it does not work. When I call

make html

I get a

make: *** No rule to make target `docs/index.html', needed by `html'.  Stop.

error, even though I think I have defined it.

SRCDIR = source
OUTDIR = docs

RMD = $(wildcard $(SRCDIR)/*.Rmd)

TMP  = $(RMD:.Rmd=.html)
HTML = ${subst $(SRCDIR),$(OUTDIR),$(TMP)}

    echo $(RMD)
    echo $(TMP)
    echo $(HTML)

all: clean update html

html:   $(HTML)

%.html: %.Rmd
    echo $(HTML)
    @Rscript -e "rmarkdown::render('$<', output_format = 'prettydoc::html_pretty', output_dir = './$(OUTDIR)/')"

    @Rscript -e "devtools::load_all(here::here()); microcosmScheme:::updateFromGoogleSheet(token = './source/googlesheets_token.rds')"

## from
    @$(MAKE) -pRrq -f $(lastword $(MAKEFILE_LIST)) : 2>/dev/null | awk -v RS= -F: '/^# File/,/^# Finished Make data base/ {if ($$1 !~ "^[#.]") {print $$1}}' | sort | egrep -v -e '^[^[:alnum:]]' -e '^[email protected]$$' | xargs

.PHONY: update clean cleanhtml all list

The variables seem to be correct:

15:21 $ make test
echo source/index.Rmd
echo source/index.html
echo docs/index.html

If I change it as follow it works, but the target points to the SRCDIR, but I want it to point to the OUTDIR:

RMD = $(wildcard $(SRCDIR)/*.Rmd)

HTML  = $(RMD:.Rmd=.html)
# HTML = ${subst $(SRCDIR),$(OUTDIR),$(TMP)}

I am sure it is one small thing...


1 Answers Makefile does not find target

This rule:

%.html : %.Rmd

tells make how to build a file foo.html from a file foo.Rmd, or a file source/foo.html from a file source/foo.Rmd, or a file docs/foo.html from a file docs/foo.Rmd.

It doesn't tell make how to build a file docs/foo.html from a file source/foo.Rmd, because the stem that matches the pattern % is not the same.

If you want to write a pattern for docs/foo.html to be built from source/foo.Rmd, you have to write it like this:

$(OUTDIR)/%.html : $(SRCDIR)/%.Rmd

so that the part that matches the pattern % is identical.

ETA Some other notes: you should be using := with the wildcard function as it's much better performing. Also you shouldn't use subst here because it replaces all occurrences of the string which could break things if any of your .Rmd files contain the string source for example (e.g., source/my_source_file.Rmd. This is much better written with patsubst, as in:

RMD := $(wildcard $(SRCDIR)/*.Rmd)
HTML := $(patsubst $(SRCDIR)/%.Rmd,$(OBJDIR)/%.html,$(RMD))

Finally, you don't show what the clean target does but it's unusual to have the clean target depended on by all. Usually it's a separate target that is invoked only when you want it, like make clean.

4 months ago