How to make GNU Make fail if a shell command assigned to a variable failed?

问题

I have a Make variable:

PASSWORD:=$(shell vault read -field=password test/password)

If vault is not installed, make will print make: vault: Command not found, but continue executing the recipe. How do I make it fail and stop execution if the expression fails?

回答1:

Here is one approach:

$ cat err.mk
PASSWORD:=$(shell vault read -field=password test/password)
ifndef PASSWORD
$(error PASSWORD not set (maybe vault failed?))
endif
$ make -f err.mk
make: vault: Command not found
err.mk:3: *** PASSWORD not set (maybe vault failed?).  Stop.

回答2:

Maybe this idea should work:

X!=lsx /

all:
ifeq (${.SHELLSTATUS},0)
    @echo OK
else
    @exit 1
endif

For example you can create a check: PHONY-target which is needed by every (other) target.

Explanation see here:

After the shell function or ‘!=’ assignment operator is used, its exit status is placed in the .SHELLSTATUS variable.

The X=$(shell ls /) doesn't work but IMHO should.

来源：https://stackoverflow.com/questions/50817458/how-to-make-gnu-make-fail-if-a-shell-command-assigned-to-a-variable-failed