$re = '/(background:\s*url\((https?:\/\/)*([a-zA-Z0-9._:\/\s*]*)\)\s*[a-zA-Z0-9\s*-._:\/;]*)/';
$str = '.nyroModalCloseButton {
top: -13px;
right: -13px;
width: 12px;
height: 12px;
text-indent: -9999em;
background: url(http://instantcms.ru/templates/_default_/images/nyromodal/close.gif) no-repeat 6px center;
}
.nyroModalCloseButton {
top: -13px;
right: -13px;
width: 12px;
height: 12px;
text-indent: -9999em;
background: url(https://instant/templates/_default_/images/nyromodal/close.gif);
}
.nyroModalCloseButton {
top: -13px;
right: -13px;
width: 12px;
height: 12px;
text-indent: -9999em;
background: url(../instant/templates/_default_/images/nyromodal/close.gif);
}';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php