This gets passed to BUILDKITE_SHELL, which will specify the shell being
used to executes script in.
Defaults to `${pkgs.bash}/bin/bash -e -c`, matching how buildkite
behaves on other distros.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.