Altering Makefile variable with sed

Question

I am trying to alter a Makefile variable with sed. I wrote a small Makefile to illustrate what I am trying to do. The CINCS variable is eventually going to be appended to the CFLAGS variable. The CSINCS variable is supposed to hold the paths of all include files, without "-I" in front.

#

SHELL = /bin/sh

SRCS = /usr/local/src/jpeg/jpeg-9b
CINCS = -I/usr/local/src/jpeg/jpeg-9b
CSINCS = $(CINCS) | sed -e "s/-I//g"

check:
@echo 1. $(SRCS)
find $(SRCS) -name "*.c" -print > cscope.files
@echo 2. $(CSINCS)
find '$(CSINCS) -name" "*.h' -print >> cscope.files
cscope -k -b
cat cscope.files | xargs ctags -u

#

I am trying to remove the "-I" in front of all the include paths. Upon exec:

$ make -f test check
1. /usr/local/src/jpeg/jpeg-9b
find /usr/local/src/jpeg/jpeg-9b -name "*.c" -print > cscope.files
2. /usr/local/src/jpeg/jpeg-9b
find '-I/usr/local/src/jpeg/jpeg-9b | sed -e "s/-I//g" -name" "*.h'   -print >> cscope.files
find: unknown predicate `-I/usr/local/src/jpeg/jpeg-9b | sed -e "s/-I//g" -name" "*.h'
test:8: recipe for target 'check' failed
make: *** [check] Error 1

At postion "2" the CSINCS variable looks correct. But there is an expansion with the "find command. That's the problem.

I know I could use the CINCS variable with the cscope command:

cscope -I $(CINCS)

but I want to use cscope.files for the ctags file as well. I could just generate a separate CSINCS variable and keep CINCS and CSINCS in sync all the time. Just curious as to what is going on.

Answer 1

You haven't told make to execute the value of CSINCS as a shell script, you need something like

CSINCS := $(shell echo $(CINCS) | sed -e "s/-I//g")

Or if you have make 4.0 or more recent

CSINCS != echo $(CINCS) | sed -e "s/-I//g"

although for something this simple you don't need to use sed or the shell

CSINCS := $(subst -I,,$(CINCS))