nixpkgs/nixos/modules/programs/shell.nix

# This module defines a standard configuration for NixOS shells.

{ config, lib, pkgs, ... }:

with lib;

let

  cfg = config.environment;

in

{

  config = {

    environment.shellAliases =
      { ls = "ls --color=tty";
        ll = "ls -l";
        l  = "ls -alh";
      };

    environment.shellInit =
      ''
        # Set up the per-user profile.
        mkdir -m 0755 -p $NIX_USER_PROFILE_DIR
        if test "$(stat --printf '%u' $NIX_USER_PROFILE_DIR)" != "$(id -u)"; then
            echo "WARNING: bad ownership on $NIX_USER_PROFILE_DIR" >&2
        fi

        if test -w $HOME; then
          if ! test -L $HOME/.nix-profile; then
              if test "$USER" != root; then
                  ln -s $NIX_USER_PROFILE_DIR/profile $HOME/.nix-profile
              else
                  # Root installs in the system-wide profile by default.
                  ln -s /nix/var/nix/profiles/default $HOME/.nix-profile
              fi
          fi

          # Subscribe the root user to the NixOS channel by default.
          if [ "$USER" = root -a ! -e $HOME/.nix-channels ]; then
              echo "${config.system.nixos.defaultChannel} nixos" > $HOME/.nix-channels
          fi

          # Create the per-user garbage collector roots directory.
          NIX_USER_GCROOTS_DIR=/nix/var/nix/gcroots/per-user/$USER
          mkdir -m 0755 -p $NIX_USER_GCROOTS_DIR
          if test "$(stat --printf '%u' $NIX_USER_GCROOTS_DIR)" != "$(id -u)"; then
              echo "WARNING: bad ownership on $NIX_USER_GCROOTS_DIR" >&2
          fi

          # Set up a default Nix expression from which to install stuff.
          if [ ! -e $HOME/.nix-defexpr -o -L $HOME/.nix-defexpr ]; then
              rm -f $HOME/.nix-defexpr
              mkdir -p $HOME/.nix-defexpr
              if [ "$USER" != root ]; then
                  ln -s /nix/var/nix/profiles/per-user/root/channels $HOME/.nix-defexpr/channels_root
              fi
          fi
        fi
      '';

  };

}