How do I use a shell assignment in a makefile so that it works with both...

distro_dave

I'd like to use the shell assignment operator (i.e., != ) in a makefile that is going to be executed on FreeBSD, macOS, and Linux. Here's an example: a!= seq 3 .PHONY: all all: $a .PHONY: $a $a: @echo $@ Here's the expected output: # touch 1 2 3 # make all 1 2 3 Unfortunately, the shell assignment operator is not supported by the GNU Make shipped with macOS Monterey 12.6.1 and the output of the example is empty. It works in more recent versions...

Originally asked by Mateusz Piotrowski on Stack Exchange (unix) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

The solution is to use the $(shell ...) construct in addition to the shell assignment operator like this: a= $(shell seq 3) a!= seq 3 .PHONY: all all: $a .PHONY: $a $a: @echo $@ The GNU Make 3.81 seems to skip the shell assignment so it uses the output of the first assignment. bmake, however, does not really care about the first assignment because the second assignment overrides it anyway. I usually use an extra variable to avoid having to repeat the command: _a= seq 3 a= $(shell ${_a}) a!= ${_a}

Full answer by Mateusz Piotrowski: https://unix.stackexchange.com/a/733310 (CC BY-SA 4.0).

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