$re = '~\[(url=https://www\.translatum\.gr.*?)\[/url]~m';
$str = 'Test aetejklkj fa jklkj dsdfs [url=https://www.translatum.gr/forum/index.php?topic=989146.0]telerobotically -> τηλερομποτικά, τηλερομποτικώς[/url] fskjlkj
Gfdsklkj fjgkjkl klkjdass
[url=https://www.in.gr/]in.gr | Όλες οι ειδήσεις - Ολοκληρωμένη κάλυψη ειδήσεων[/url] Gfdsklkj fjgkjkl klkjdass Gfdsklkj fjgkjkl klkjdass Gfdsklkj fjgkjkl klkjdass Gfdsklkj fjgkjkl klkjdass Gfdsklkj fjgkjkl klkjdass
Gfdsklkj fjgkjkl klkjdassGfdsklkj fjgkjkl klkjdassGfdsklkj fjgkjkl klkjdass Gfdsklkj fjgkjkl klkjdassGfdsklkj fjgkjkl klkjdassGfdsklkj fjgkjkl klkjdass ';
$subst = "[i\1[/iurl]";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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