General question for AMReX ParmParse defaults, but specifically for MPI environments in HPC:

In Python scripts for batch systems, we often need to set amrex.use_gpu_aware_mpi=1 externally.

Do you think we could define an optional environment variable in AMReX, say AMREX_USE_GPU_AWARE_MPI that at runtime changes the default of AMReX if set? The precedence would be as always:

1. CLI option
2. inputs file
3. environment option
4. hard-coded default

The current work-around is the re-implement all CLI options on the running Python process as CLI args parser, which is not scalable and not uniform across projects.