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 $(VERSION) of $(PACKAGE_NAME) has been released

It can be downloaded from $(DOWNLOAD_URL)

etc, etc"

But I can't seem to find a way to do this. Is it possible?

Answer 1

Yes. You escape the newlines with \:

VARIABLE="\
THIS IS A VERY LONG\
TEXT STRING IN A MAKE VARIABLE"

update

Ah, you want the newlines? Then no, I don't think there's any way in vanilla Make. However, you can always use a here-document in the command part

foo:
    echo <<EOF
    Here is a multiple line text
    with embedded newlines.
    EOF

Answer 2

GNU `make' manual, 6.8: Defining Variables Verbatim

Answer 3

Not really a helpful answer, but just to indicate that 'define' does not work as answered by Ax (did not fit in a comment):

VERSION=4.3.1
PACKAGE_NAME=foobar
DOWNLOAD_URL=www.foobar.com

define ANNOUNCE_BODY
    Version $(VERSION) of $(PACKAGE_NAME) has been released
    It can be downloaded from $(DOWNLOAD_URL)
    etc, etc
endef

all:
    @echo $(ANNOUNCE_BODY)

It gives an error that the command 'It' cannot be found, so it tries to interpret the second line of ANNOUNCE BODY as a command.

Answer 4

Yes, you can use the define keyword to declare a multi-line variable, like this:

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

It can be downloaded from $(DOWNLOAD_URL).

etc, etc.
endef

The tricky part is getting your multi-line variable back out of the makefile. If you just do the obvious thing of using "echo $(ANNOUNCE_BODY)", you'll see the result that others have posted here -- the shell tries to handle the second and subsequent lines of the variable as commands themselves.

However, you can export the variable value as-is to the shell as an environment variable, and then reference it from the shell as an environment variable (NOT a make variable). For example:

export ANNOUNCE_BODY
all:
    @echo "$$ANNOUNCE_BODY"

Note the use of $$ANNOUNCE_BODY, indicating a shell environment variable reference, rather than $(ANNOUNCE_BODY), which would be a regular make variable reference. Also be sure to use quotes around your variable reference, to make sure that the newlines aren't interpreted by the shell itself.

Of course, this particular trick may be platform and shell sensitive. I tested it on Ubuntu Linux with GNU bash 3.2.13; YMMV.

Hope that helps,

Eric Melski

Answer 5

Why don't you make use of the \n character in your string to define the end-of-line? Also add the extra backslash to add it over multiple lines.

ANNOUNCE_BODY=" \n\
Version $(VERSION) of $(PACKAGE_NAME) has been released \n\
\n\
It can be downloaded from $(DOWNLOAD_URL) \n\
\n\
etc, etc"

Answer 6

It worked for me:

ANNOUNCE_BODY="first line\\nsecond line"

all:
    @echo -e $(ANNOUNCE_BODY)