%% Justin Chen-Wells <[EMAIL PROTECTED]> writes:
jc> In real life I've hacked it to work like this:
jc> include2: include1
jc> @echo "B := ^(A)" | tr ^ $$> $@
jc> which winds up writing a literal $(A) to the generated file.
jc> This also shows my ignorance about the right way to escape $
jc> in this case. I had wanted to write
jc> @echo "B := $$(A)" > $@
jc> but that doesn't work, so I tricked make with the ^/tr hack.
You just need a bit of education about make and shell
quoting... particularly shell quoting, it looks like.
Remember that there are two things happening: first, make will expand
any make variables in the script. Then it will send the script to the
shell, and the shell will _also_ expand any _shell_ variables it sees.
Both make and shell use "$" to introduce a variable, so this means you
have to be careful and sometimes double-escape things.
In make, there is only one way to escape a variable, and that is by
using double-$ ("$$").
In shell, there are two ways: first by using a backslash (\$foo) or
second by using single quotes ('$foo'). The shell does not expand
within single quotes but it _DOES_ expand within double quotes
("$foo"). So, your command:
include2:
echo "B := $$(A)" > $@
expands like this: first, make gets into the act and expands the above
to this command line:
echo "B := $(A)" > include2
and sends that to the shell. The shell looks at it and sees the "$" and
wants to expand it, but "$(A)" is an illegal shell variable syntax so it
probably gives an error. You need to quote that "$" for the shell. You
can do it either with the single-quote solution I posted before:
echo 'B := $$(A)' > $@
or with a backslash:
echo "B := \$$(A)" > $@
Like I said, understanding _both_ make and shell quoting is critical to
writing anything more than basic makefiles.
HTH!
--
-------------------------------------------------------------------------------
Paul D. Smith <[EMAIL PROTECTED]> Find some GNU make tips at:
http://www.gnu.org http://make.paulandlesley.org
"Please remain calm...I may be mad, but I am a professional." --Mad Scientist
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