How exactly are file arguments passed to the executables?

[GeigerJ2]

Consider the attached simplified workflow, in which the init cycle and only one ICON are being executed:
How are the actual file references passed around? For instance, in the call to the ICON executable, how are the locations of "icon input" and "grid file" passed to ICON? As positional parameters or via option flags (--grid-file <path_to_gridfile>). For further development of the AiiDA-powered runner, it would be very beneficial for us, if we could see how one would run the workflow without any workflow manager, by calling the executables / scripts manually, modifying file locations, etc.

Pinging @agoscinski and @leclairm.

[leclairm]

input location has to be put in a namelist. If a rel_path is provided in the config yaml file, it should replace what is in the namelist, otherwise, use the locations provided in the namelist. Actually the path to the namelist should probably be provided as a relative path to the config file in the task description under runtime, stg like that.
To handle namelists, I'll use the f90nml package.

[GeigerJ2]

So if I understand correctly, everything, including paths to files, will be put in one input file? How would one run ICON from the command line? Just:

icon <namelist_file>

Or are there additional command-line options?

[agoscinski]

In a meeting we clarified that the namelist is assumed to be in the same directory with a certain name. The aiida-icon plugin will take care of it (see calcjob input port). In our part of the code one has to only specify the name through our plugin interface (which we still need to decide how to do, here is the draft PR #20, but this is outside of the issue)