Users (or developers!) may not realize that the shell expands glob asterisk
* unless enclosed in quotes.
This can surprise users unfamiliar with this shell behavior, say when using Python argparse with position-based arguments.
Say a user has a single file to process in a directory, and doesn’t want to type the long filename, so they type:
python myScript.py ~/data/*.h5 32
Here we assume myScript.py expects two positional arguments, the first being a filename, and the second being an integer. If more than one “*.h5” file subsequently exists and myScript.py is run, the actual input to Python would be like:
python myScript.py ~/data/file1.h5 ~/data/file2.h5 32
Which causes a Python argparse exception.
To see what the shell is going to expand to, with default keybindings and Bash or Zsh at least, press after typing the command these keys:Ctrlx g