nix/doc/manual/rl-next/nix-shell-looks-for-shell-nix.md

synopsis	significance	issues	prs
`nix-shell <directory>` looks for `shell.nix`	significant	496 2279 4529 5431 11053	11057

nix-shell $x now looks for $x/shell.nix when $x resolves to a directory.

Although this might be seen as a breaking change, its primarily interactive usage makes it a minor issue. This adjustment addresses a commonly reported problem.

This also applies to nix-shell shebang scripts. Consider the following example:

#!/usr/bin/env nix-shell
#!nix-shell -i bash

This will now load shell.nix from the script's directory, if it exists; default.nix otherwise.

The old behavior can be opted into by setting the option nix-shell-always-looks-for-shell-nix to false.

Author: Robert Hensing (@roberth)