Set path to file at runtime form the command line or read it from a command

[Barabas5532]

Is there any way to set the path to a file at runtime as an argument to fusesoc run? For example, as a run flag with a string value rather than a boolean, or through an environment variable (described in #487 but I can't find it in the docs).

More precisely, I'm looking to replicate the behaviour of this line of bash: iverilog -o demo.vvp demo_tb.v demo_new.v $( yosys-config --datdir/ice40/cells_sim.v ), where yosys-config return the string "/usr/share/yosys/ice40/cells_sim.v" or another path depending on how yosys is installed on the system. Is there any way to get this path into a fusesoc core without editing the core file?