Is it possible to include command line options in the python shebang?

Question

I have the canonical shebang at the top of my python scripts.

#!/usr/bin/env python

However, I still often want to export unbuffered output to a log file when I run my scripts, so I end up calling:

$ python -u myscript.py &> myscript.out &

Can I embed the -u option in the shebang like so...

#!/usr/bin/env python -u

and only call:

$ ./myscript.py &> myscript.out &

...to still get the unbuffering? I suspect that won't work, and want to check before trying. Is there something that would accomplish this?

Answer 1

In new versions of env since coreutils 8.30 there is option -S for this. Citation from man env:

   The -S option allows specifing multiple parameters in a script.  Running a script named 1.pl containing the follow‐
  ing first line:

         #!/usr/bin/env -S perl -w -T

  Will execute perl -w -T 1.pl .

  Without the '-S' parameter the script will likely fail with:

         /usr/bin/env: 'perl -w -T': No such file or directory

Answer 2

You can have arguments on the shebang line, but most operating systems have a very small limit on the number of arguments. POSIX only requires that one argument be supported, and this is common, including Linux.

Since you're using the /usr/bin/env command, you're already using up that one argument with python, so you can't add another argument -u. If you want to use python -u, you'll need to hard-code the absolute path to python instead of using /usr/bin/env, e.g.

#!/usr/bin/python -u

See this related question: How to use multiple arguments with a shebang (i.e. #!)?