I'm trying to write a script that could take all files in a directory and allowing the user to use the * to refer to multiple files. This is the line in which I set up the parser to receive the input files: parser.add_argument('-f', '--files', help='The files to compare.', required=True, nargs='+') This is the line of the error Invalid argument: '.\\rmsd\\*.xyz' This is the code I run to execute the script python .\rsmd.py -r .\rmsd\1.xyz -f .\rmsd\*.xyz My purpose is to let the user use the script in Windows and in Linux. Continue reading...