concatTextFile: add passthru argument

    , destination ? ""   # relative path appended to $out eg "/bin/foo"

    , checkPhase ? ""    # syntax checks, e.g. for scripts

    , meta ? { }

    , passthru ? { }

    }:

    runCommandLocal name

      { inherit files executable checkPhase meta destination; }

      { inherit files executable checkPhase meta passthru destination; }

      ''

        file=$out$destination

        mkdir -p "$(dirname "$file")"