{ stdenv, fetchurl , enableACLs ? true, acl ? null }: assert enableACLs -> acl != null; stdenv.mkDerivation { name = "rsync-3.0.6"; src = fetchurl { url = http://rsync.samba.org/ftp/rsync/src/rsync-3.0.6.tar.gz; sha256 = "1cz1adlshjwwi41yqhw7wph7vq58a73b4zgs8piv6rnbcj9rdk1k"; }; buildInputs = stdenv.lib.optional enableACLs acl; meta = { homepage = http://samba.anu.edu.au/rsync/; description = "A fast incremental file transfer utility"; }; }