please help with regular expression in preg_replace

["Red" <red@xxxxxx>]

hello, im not a php developer, i just need to rewrite one php file but having problem with understanding syntax of regexp in php.

i need to get domain name from fqdn (for example from $_SERVER['HTTP_HOST'] )

in sed its working well with "s/[^.]*\.//" , but preg_replace behaves weird.


http_host is for example hostname.domain.com

<?php
$host = $_SERVER['HTTP_HOST'];
exec( "echo $host | sed s/[^.]*\.//", $domain ) ;
echo "$domain[0]"
?>

return "domain.com", but

<?php
$host = $_SERVER['HTTP_HOST'];
$domain = preg_replace( '/[^.]*\./' , '', $host) ;
echo "$domain";
?>

return only "com"

i think when this php page get many hits, its not so wise to call sed everytime, i would like to ask someone for help how to write preg_replace pattern.

thanx 

Rene