Python has an easy-to-use argument parsing library. This library can be used within an ldmx-sw configuration script in order to change the parameters you are passing to the processors or even to change which processors you use.

For example, I use the code snippet often to pass inputs to the process.

import argparse
from pathlib import Path

parser = argparse.ArgumentParser()
parser.add_argument('run_number',type=int,help='run number for this simulation run')
parser.add_argument('-o','--out-dir',type=Path,help='output directory to write event data to')
args = parser.parse_args()

from LDMX.Framework import ldmxcfg
p = ldmxcfg.Process('example')
p.run = args.run_number
p.outputFile = [
  str(args.out_dir / f'my_special_simulation_run_{p.run:04d}.root')
]

# rest of configuration

Looking at the argparse library linked above is highly recommended since it has a lot of flexibility and can make passing arguments into your config very easy.

Python's pathlib library is helpful for doing the common tasks of finding files, listing files, and making a new file path.

For example, if input_dir is a pathlib.Path for an input directory of ROOT files.

p.inputFiles = [ str(f) for f in input_dir.iterdir() if f.suffix == '.root' ]

We can also use an input file input_file to get an output file name and an output directory output_dir to place this file in the directory we want.

p.outputFiles = [ str(output_dir / (input_file.stem + '_with_my_analyzer.root')) ]