Recommended reading: The UNIX FAQ: Why do some scripts start with #! … ? The #! magic, details about the shebang/hash-bang mechanism on various Unix flavours Wikipedia: Shebang The unix kernel’s program loader is responsible for doing this. When exec() is called, it asks the kernel to load the program from the file at its … Read more
Running a command through /usr/bin/env has the benefit of looking for whatever the default version of the program is in your current environment. This way, you don’t have to look for it in a specific place on the system, as those paths may be in different locations on different systems. As long as it’s in … Read more
This sums it up better than I can say it: http://docs.python.org/faq/windows.html More specifically, check out the 2nd section titled “How do I make Python scripts executable?” On Windows, the standard Python installer already associates the .py extension with a file type (Python.File) and gives that file type an open command that runs the interpreter (D:\Program … Read more
Read up on the Python Launcher for Windows in the docs, which was initially described in PEP 397. It lets you define custom shebang configurations in “py.ini” (e.g. to use pypy), and out of the box you can use virtual shebangs such as #!/usr/bin/env python3, or shebangs with real paths such as #!”C:\Python33\python.exe”. (Quoting is … Read more
It’s a convention so the *nix shell knows what kind of interpreter to run. For example, older flavors of ATT defaulted to sh (the Bourne shell), while older versions of BSD defaulted to csh (the C shell). Even today (where most systems run bash, the “Bourne Again Shell”), scripts can be in bash, python, perl, … Read more
In some environment, env doesn’t split arguments. So your env is looking for python -u in your path. We can use sh to work around. Replace your shebang with the following code lines and everything will be fine. #!/bin/sh ””exec python -u — “$0″ ${1+”$@”} # ”’ # vi: syntax=python p.s. we need not worry … Read more
The shebang line has never been specified as part of POSIX, SUS, LSB or any other specification. AFAIK, it hasn’t even been properly documented. There is a rough consensus about what it does: take everything between the ! and the \n and exec it. The assumption is that everything between the ! and the \n … Read more
You should use #!/usr/bin/env bash for portability: different *nixes put bash in different places, and using /usr/bin/env is a workaround to run the first bash found on the PATH. And sh is not bash.
The shebang line in any script determines the script’s ability to be executed like a standalone executable without typing python beforehand in the terminal or when double clicking it in a file manager (when configured properly). It isn’t necessary but generally put there so when someone sees the file opened in an editor, they immediately … Read more
If you have several versions of Python installed, /usr/bin/env will ensure the interpreter used is the first one on your environment’s $PATH. The alternative would be to hardcode something like #!/usr/bin/python; that’s ok, but less flexible. In Unix, an executable file that’s meant to be interpreted can indicate what interpreter to use by having a … Read more