Dynamically plug argument into shell command in Makefile routine

Question

I am passing an argument to a Makefile routine, and am based on that determining which argument to pass to a subsequent shell command.

target:
    if [ "$(tensorflowgpu)" = "false" ]; then \
        conda env create -f temp-environment.yaml \
    else \
        conda env create -f environment.yaml \
    fi

I'm wondering if there is a way to plug the respectively apt .yaml file name directly into the conda create command without using the if else fi syntax. A ternary operator which does not assign its result to a variable seems to be unavailable in shell scripts.

If that really isn't feasible at all, I'm wondering if there's some other way to make this piece of code a little more maintainable and readable, apart from refactoring the conda create command to a function and passing the yaml file to that, maybe.

Disclaimer: I'm not too proficient with shell scripting.

MadScientist · Accepted Answer · 2022-09-23 18:15:41Z

1

You could do it like this:

target:
        [ "$(tensorflowgpu)" = "false" ] && prefix=temp- || prefix= ; \
        conda env create -f $${prefix}environment.yaml

I don't know if you like that any better.

Or, since you're using make variables here not shell variables, if you're willing to rely on GNU make, you could use constructed variable names:

YAMLFILE_false = temp-environment.yaml
YAMLFILE_base = environment.yaml

YAMLFILE = $(firstword $(YAMLFILE_$(tensorflowgpu)) $(YAMLFILE_base))

target:
        conda env create -f $(YAMLFILE)

Or you could use GNU make's if function; for example:

target:
        conda env create -f $(if $(filter false,$(tensorflowgpu)),temp-)environment.yaml

or you could put it in a variable to make it a little cleaner:

YAMLFILE = $(if $(filter false,$(tensorflowgpu)),temp-)environment.yaml

target:
        conda env create -f $(YAMLFILE)

answered Sep 23, 2022 at 18:15

MadScientist

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2 Comments

w2sv Over a year ago

Damn that's awesome, thank you so much for all those different ways of doing it. Particularly the if function is very much to my liking, I hadn't heard of that one at all before

MadScientist Over a year ago

FYI: gnu.org/software/make/manual/html_node/Functions.html

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