== Nix-shell shebangs

You can use `nix-shell` to run scripts in arbitrary languages, providing
the necessary dependencies. This is particularly convenient for
standalone scripts because you don’t need to create a repo and write a
separate `flake.nix`.

The script should start with two ``shebang'' (`#!`) commands. The first
should invoke `nix-shell`. The second should declares the scrpt
interpreter and any dependencies. Here are some examples.

=== A Bash script depending on a package in the nixpkgs repo.

Script:

[source,bash,linenums]
....
include::bash-with-nixpkg.sh[]
....

Output:

....
$# shebangs/bash-with-nixpkg.sh
....

=== A Python script depending on a package in the nixpkgs repo.

Script:

[source,bash,linenums]
....
include::python-with-nixpkg.sh[]
....

Output:

....
$# shebangs/python-with-nixpkg.sh
....
