Without -S, `uv run --script` would be treated as a binary name (including spaces) and you will get an error like "env: ‘uv run --script’: No such file or directory".
-S causes the string to be split on spaces and so the arguments are passed correctly.
On these systems, wouldn’t binfmt attempt to exec(“/usr/bin/env -S uv run --script”, “foo.py”) and fail anyway for the same reason?
No. The string is split to extract at most one argument. See: https://linux.die.net/man/2/execve
So in fact "-S" is not passed as a separate argument, but as a prefix in the first (and only) argument, and env then extracts it and acts accordingly:
``` $ /usr/bin/env "-S echo deadbeef" deadbeef ```
Most systems split at least the 1st space since decades.