Using Makefile to clean subdirectories

Question

Is it possible to perform a make clean from the parent directory which also recursively cleans all sub-directories without having to include a makefile in each sub-directory?

Answer 1

You cannot without help of an external program. The best is a shell script that does the recursion and calls make in each of the subdirectories (look at my comment to @robert in his response) Something like this will do the work (and does not depend on GNU make features)

#!/bin/sh
ROOTDIR=`/bin/pwd`
for dir in `find . -type d -print`
do
    make -C "${dir}" -f "${ROOTDIR}"/Makefile clean
done

of course, you can put this sequence (in target cleanrec) inside your Makefile

cleanrec:
    ROOT=`/bin/pwd`; \
    for dir in `find . -type d -print`; \
    do \
        make -C "$${dir}" -f "$${ROOTDIR}"/Makefile clean; \
    done

and conserve your clean target for local cleaning of a single directory. The reason is that Makefile has only static info to do the make, and you have to get some external help to know what subdirectories you have in each directory. So, in case you are going to get external help, you'd better to use a good tool as find(1) and sh(1)