How to use sed in a Makefile

Question

I have tried putting the following in my Makefile:

@if [ $(DEMO) -eq 0 ]; then \
    cat sys.conf | sed -e "s#^public_demo[\s=].*$#public_demo=0#" >sys.conf.temp; \
else \
    cat sys.conf | sed -e "s#^public_demo[\s=].*$#public_demo=1#" >sys.conf.temp; \
fi

but when I run make, I get the following error:

sed: -e expression #1, char 30: unterminated `s' command

If I run the exact lines that contain sed in the console, they behave correctly.

Why am I getting this error and how can the problem be fixed?

Answer 1

I suggest you use single quotes instead of double quotes, the $ might be processed as a special char by make before running sed:

cat sys.conf | sed -e 's#^public_demo[\s=].*$#public_demo=0#' >sys.conf.temp;

Answer 2

Use something else than # to separate parts.

Answer 3

It might be the $ sign in the substitution that is interpreted by make as a variable. Try using two of them like .*$$#public_demo. Then make will expand that to a single $.

EDIT: This was only half the answer. As cristis answered: the other part is that one needs to use single quotes to prevent bash from expanding the $ sign too.