anchor.diff: -{ stdenv, fetchurl, fetchpatch, bison, flex, pam
  +{ stdenv, fetchurl, fetchpatch, bison, flex, pam, perl
   , sendmailPath ? "/run/wrappers/bin/sendmail"
   , atWrapperPath ? "/run/wrappers/bin/at"
   }:
  
positive.code:     })
    ];
  
    nativeBuildInputs = [ bison flex ];
  
    buildInputs = [ pam ];
  
  
negative.code:     "--with-daemon_groupname=atd"
    ];
  
    doCheck = true;
  
    # Ensure that "batch" can invoke the setuid "at" wrapper, if it exists, or
    # else we get permission errors (on NixOS). "batch" is a shell script, so
  