> Based on the man page it doesn’t appear to be doing anything useful here

The man page tells me:

  -S, --split-string=S
         process and split S into separate arguments; used to pass multi‐
         ple arguments on shebang lines

Without that, the system may try to treat the entirety of "uv run --script" as the program name, and fail to find it. Depending on your env implementation and/or your shell, this may not be needed.

See also: https://unix.stackexchange.com/questions/361794

Right, I didn’t think about the shebang case being different. Thanks!

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.