Targets in the form of {a,b} are not recognized in my Makefile

Question

I have the following makefile:

SHELL:/bin/bash

all: euro.n.{a,b}

euro.{a,b}:
        touch euro.{a,b}

euro.n.{a,b}: euro.{a,b}
        cat euro.a > euro.n.a
        cat euro.b > euro.n.b

Now if I run make twice, the makefile won't recognize in the second run that the files euro.na and euro.nb have already been created (and it will be executed again).

What is the problem?

Answer 1

What is the problem?

{a,b} is not syntax recognized by GNU make.

SHELL := /bin/bash (you missed = there) only affects the syntax of recipes.

---

One alternative solution:

SHELL := /bin/bash

all: $(addprefix euro.n.,a b)

euro.%:
        touch $@

euro.n.% : euro.%
    cp $< $@