foo.nix

{
      interactiveShellInit = ''
          #####################################################################
          # shell independent prompts #########################################
          #####################################################################

          # Read a single char from /dev/tty, prompting with "$*"
          # Note: pressing enter will return a null string. Perhaps a version terminated with X and then remove it in caller?
          # See https://unix.stackexchange.com/a/367880/143394 for dealing with multi-byte, etc.
          function get_keypress {
            local REPLY IFS=
            >/dev/tty printf '%s' "$*"
            [[ $ZSH_VERSION ]] && read -rk1  # Use -u0 to read from STDIN
            # See https://unix.stackexchange.com/q/383197/143394 regarding '\n' -> '''
            [[ $BASH_VERSION ]] && </dev/tty read -rn1
            printf '%s' "$REPLY"
          }

          # Get a y/n from the user, return yes=0, no=1 enter=$2
          # Prompt using $1.
          # If set, return $2 on pressing enter, useful for cancel or defualting
          function get_yes_keypress {
            local prompt="''${1:-Are you sure [y/n]? }"
            local enter_return=$2
            local REPLY
            # [[ ! $prompt ]] && prompt="[y/n]? "
            while REPLY=$(get_keypress "$prompt"); do
              [[ $REPLY ]] && printf '\n' # $REPLY blank if user presses enter
              case "$REPLY" in
                Y|y)  return 0;;
                N|n)  return 1;;
                ''')   [[ $enter_return ]] && return "$enter_return"
              esac
            done
          }

          # Credit: http://unix.stackexchange.com/a/14444/143394
          # Prompt to confirm, defaulting to NO on <enter>
          # Usage: confirm "Dangerous. Are you sure?" && rm *
          function confirm {
            local prompt=''${*:-Are you sure} [y/N]? "
            get_yes_keypress "$prompt" 1
          }

          # Prompt to confirm, defaulting to YES on <enter>
          function confirm_yes {
            local prompt="''${*:-Are you sure} [Y/n]? "
            get_yes_keypress "$prompt" 0
          }
          #####################################################################
          #####################################################################
          #####################################################################

        alias  up='nixos-rebuild test --upgrade '
        function upn {
          cd $NIXPKGS &&
          if [[ $(git status --porcelain ) == "" ]];
          then
            echo "checking out commit " $(nixos-version --hash) " under branch name " $(nixos-version | cut -d" " -f1)
            git fetch upstream && git checkout $(nixos-version --hash) -b $(nixos-version | cut -d" " -f1)
          else
            git status
          fi
        }
        alias gcn='cd $NIXPKGS && git checkout $(nixos-version | cut -d" " -f1)'
        alias  te='nixos-rebuild test   -p rt -I nixos-config=/home/bart/nixosConfig/machines/$(hostname | cut -d"-" -f1)/rt.nix                     && nixos-rebuild test'
        alias ten='nixos-rebuild test   -p rt -I nixos-config=/home/bart/nixosConfig/machines/$(hostname | cut -d"-" -f1)/rt.nix -I nixpkgs=$NIXPKGS && nixos-rebuild test   -I nixpkgs=$NIXPKGS'
        alias  sw='nixos-rebuild boot -p rt -I nixos-config=/home/bart/nixosConfig/machines/$(hostname | cut -d"-" -f1)/rt.nix                     && nixos-rebuild switch'
        alias swn='nixos-rebuild switch -p rt -I nixos-config=/home/bart/nixosConfig/machines/$(hostname | cut -d"-" -f1)/rt.nix -I nixpkgs=$NIXPKGS && nixos-rebuild switch -I nixpkgs=$NIXPKGS'

        nga() {
          if confirm "Delete all generations and vacuum the systemd journal?"; then
            nix-collect-garbage -d && journalctl --vacuum-time=2d
          else
            echo "\nOK, we'll keep it all"
          fi
        }

        ngd() {
          if [[ -n "$1" ]] && [[ "$1" =~ ^-?[0-9]+$ ]]; then
            if confirm "Delete all generations and vacuum the systemd journal except for the last $1 days?"; then
              nix-collect-garbage --delete-older-than $1d && journalctl --vacuum-time=$1d
            else
              echo "\nOK, we'll keep it all."
            fi
          else
            echo "\nYou need to give the number of days you want to keep!"
          fi
        }

        lg() {
          echo "System generations\n"
          nix-env -p /nix/var/nix/profiles/system --list-generations
          echo "\n\nRT generations:\n"
          nix-env -p /nix/var/nix/profiles/system-profiles/rt --list-generations
        }

        dgs() {
          if [[ -n "$@" ]] && [[ "$@" =~ ^-?[0-9]+$ ]]; then
            nix-env -p /nix/var/nix/profiles/system --delete-generations $@
          else
            echo "\nYou need to tell me which generations to delete!"
          fi
        }

        dgr() {
          if [[ -n "$@" ]] && [[ "$@" =~ ^-?[0-9]+$ ]]; then
            nix-env -p /nix/var/nix/profiles/system-profiles/rt --delete-generations $@
          else
            echo "\nYou need to tell me which generations to delete!"
          fi
        }

        vi() {emacseditor --create-frame --quiet --no-wait "$@"}
        # export EDITOR="vi"

      '';
    };
    }