nix-shell, as interpreter, seems to follow symlinks looking for {shell|default}.nix

[chreekat]

Consider this log, where a trivial setup works fine, unless the script is a symlink:

$ cat default.nix
{ }:
with (import <nixpkgs> {});
runCommand "test" { buildInputs = [ pkgs.hello ]; } ""

$ cat test.sh
#!/usr/bin/env nix-shell
#! nix-shell --pure -i bash
hello

$ ./test.sh
Hello, world!

$ mv test.sh aa && ln -s aa/test.sh

$ ./test.sh
error: getting status of ‘/home/b/tmp/nix-shell-interpreter/aa/default.nix’: No such file or directory

Expected behavior

It surprised me that the symlink was followed. My scenario is that certain scripts are located in one location, but I would like to use them in the context of another location. Symlinks seem like a reasonable way to do this. But maybe I could be convinced otherwise.

Info

• system: "x86_64-linux"
• host os: Linux 4.9.86, NixOS, 17.09.3243.bca2ee28db4 (Hummingbird)
• multi-user?: yes
• sandbox: no
• version: nix-env (Nix) 1.11.16
• channels(root): "nixos-17.09.3243.bca2ee28db4"
• channels(b): "unstable-18.09pre138871.af55a0c3002"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs

[FRidh]

#2109 related?

[chreekat]

Yes, it does seem related, in that that issue was opened by someone with the opposite intuition running into the opposite behavior. Fun!

[chreekat]

By the way, for this issue, hard links work fine. It's just symlinks that surprise me.

[chreekat]

I've changed my tune; I'm ok with symlinks acting like portals. Closing.