Hash inside Makefile shell call causes unexpected behaviour
You have to escape the hash twice in order to use it inside functions: once for Make and once again for the shell.
That is,
FILE = $(shell echo \\\#include\ \<ham/hamsterdb.h\>)Notice three backslashes instead of two as one could expect. The third backslash is needed because otherwise the first one would escape the second and the hash would be still unescaped.
UPD.
Another possible solution is to only escape the hash for Make and use Bash single quotes to prevent interpreting the hash as a shell comment. This also eliminates the need of escaping spaces, < and >:
FILE = $(shell echo '\#include <ham/hamsterdb.h>')