> It seems to be a problem that is related to macOS?
Nope, works fine here, and I see no reason why an `execlp` call to such a simple script would fail, given that `copier.sh` is on PATH with executable bit set. I suggest you try the following to make sure:
```fish
$ copier.sh test && pbpaste
# should see "test"
```
```fish
$ export NNN_COPIER="$HOME/.config/fish/copier.sh"
$ nnn
```
Easy. I bet $10 on either
- `~/.config/fish` is not in `PATH`; or
- `~/.config/fish/copier.sh` is not executable;
or both.