$re = '`url\((?:[\'"]?(?:https?|data):[^\'"\)]+[\'"]?|[\'"]?([^\'")]+)[\'"]?)\)`m';
$str = '1. background: url(https://images/magnifier-ico.svg) no-repeat left center;
2. background: url(http://images/magnifier-ico.svg) no-repeat left center;
1. background: url(\'https://images/magnifier-ico.svg\') no-repeat left center;
2. background: url("http://images/magnifier-ico.svg") no-repeat left center;
background: url(\'images/magnifier-ico.png\') no-repeat left center;
background: url("/images/magnifier-ico.svg") no-repeat left center;
background: url(./images/magnifier-ico.svg) no-repeat left center;
background: url(../images/magnifier-ico.svg) no-repeat left center;
background: url(../images/magnifier-ico.svg) no-repeat left center;
background: url(../images/magnifier-ico.svg) no-repeat left center;
background: url(../images/magnifier-ico.svg) no-repeat left center;
background: url(../images/magnifier-ico.svg) no-repeat left center;
';
preg_match_all($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