make: Use grep to look for specific string in all files within a folder

Question

I'd like to look for a specific set of strings in files with a specific file extension (here it's .textfile ) I have in the current folder. For this, I want to use make .

Beforehand, I convert all .pdf files to .txt files and rename their .txt extension to .textfile . The filename itself is to be left "unharmed" during the conversion. My code so far:

#Variables that save the filenames of all .pdf files
SOURCE=$(wildcard *.pdf)
OBJECT=$(SOURCE:.pdf=.textfile)

#The conversion target
textfile: $(OBJECT)                     
%.textfile: %.pdf
    @pdftotext -f $(FROM_PAGE) $< $@

To look for a set of string within these files, I've added this to the code:

lookfor-%: $(OBJECT)
    grep -H % $<

So calling make lookfor-Foo would look for "Foo" in all .converted files within the folder. If there is a match, it would print this to stdin:

file1.converted: Foo is here
file231.converted: here is Foo for you!

However, my Makefile doesn't do this. It always prints out the exact same 2 lines as a "match", even though the set of strings I'm looking for isn't even in any of these lines.

What am I doing wrong?

Answer 1

Your rule is incorrect. You need to use the pattern stem $* as the search pattern for grep ...

lookfor-%: $(OBJECT)
    grep -H '$*' $<