Is it possible to create a multi-line string variable in a Makefile

Question

I want to create a makefile variable that is a multi-line string (e.g. the body of an email release announcement). something like

ANNOUNCE_BODY=\"
Version $         


        

Answer 1

You should use "define/endef" Make construct:

define ANNOUNCE_BODY
Version $(VERSION) of $(PACKAGE_NAME) has been released.

It can be downloaded from $(DOWNLOAD_URL).

etc, etc.
endef

Then you should pass value of this variable to shell command. But, if you do this using Make variable substitution, it will cause command to split into multiple:

ANNOUNCE.txt:
  echo $(ANNOUNCE_BODY) > $@               # doesn't work

Qouting won't help either.

The best way to pass value is to pass it via environment variable:

ANNOUNCE.txt: export ANNOUNCE_BODY:=$(ANNOUNCE_BODY)
ANNOUNCE.txt:
  echo "$${ANNOUNCE_BODY}" > $@

Notice:

1. Variable is exported for this particular target, so that you can reuse that environment will not get polluted much;
2. Use environment variable (double qoutes and curly brackets around variable name);
3. Use of quotes around variable. Without them newlines will be lost and all text will appear on one line.