d273db48c6
A shared exported guard `__NIXOS_SET_ENVIRONMENT_DONE` is introduced that can be used to prevent child shells from sourcing `system.build.setEnvironment` the second time. This fixes e.g. `nix run derivation` when run from e.g. ZSH through the console or ssh. Before this Bash would resource the common environment resetting the `PATH` environment variable. We also export `system.build.setEnvironment` to `/etc/set-environment` making it easy to reset the common environment with `. /etc/set-environment` when needed and to grep for environment variables in `/etc` (which was the motivation of #30418). This reverts changes made in b00a3fc6fd82834114771f2115a2b032f0ebfe29 (the original #30418).
*** 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.