$buf = preg_replace('#news\.php\?readmore=([0-9]*?)(\'|")#si', 'skaitytinaujiena-id-\1\2', $buf);

$buf = preg_replace('#news\.php\?readmore=([0-9]*?)(&|&)rstart=([0-9]*?)(\'|")#si', 'skaitytinaujiena-id-komentaras-\3\4', $buf);

RewriteRule ^skaitytinaujiena-id-([0-9]+)$ news.php?readmore=$1 [L]

RewriteRule ^skaitytinaujiena-id-komentaras-([0-9]+)$ news.php?readmore=$1&rstart=$2 [L]

www.adresas.lt/news.php?readmore=9&rstart=0

redirect($clink."&rstart=".$c_start);