anchor.diff:      sha256 = "0r84kwa5fl0sjdashcn4vh7hgfm7ahdcysig3mcjvpmkzi7p9g8h";
     };
   
  -  buildInputs = [ ncurses ];
  +  buildInputs = [ ncurses ]
  +    ++ lib.optional withSystemd systemd;
     nativeBuildInputs = [ pkgconfig ];
   
     makeFlags = [ "usrbin_execdir=$(out)/bin" ]
  
positive.code: { lib, stdenv, fetchurl, ncurses, pkgconfig
  
  # procps is mostly Linux-only. Most commands require a running Linux
  # system (or very similar like that found in Cygwin). The one
  # exception is ‘watch’ which is portable enough to run on pretty much
  # any UNIX-compatible system.
  , watchOnly ? !(stdenv.isLinux || stdenv.isCygwin) }:
  
  stdenv.mkDerivation rec {
    name = "procps-${version}";
  
negative.code: 
    # Too red
    configureFlags = [ "--disable-modern-top" ]
      ++ lib.optional withSystemd "--with-systemd"
      ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform)
      [ "ac_cv_func_malloc_0_nonnull=yes"
        "ac_cv_func_realloc_0_nonnull=yes" ];
  