php mysql connect socket error (2)

php의 경우
if(!$con=mysql_connect("localhost","mysql","passwd")){
↓
if(!$con=mysql_connect("localhost:/var/lib/mysql/mysql.sock","mysql","passwd")){

Perl의 경우
$dbh=DBI->connect("DBI:mysql:tsumiki:localhost","mysql","passwd",
{RaiseError=>0,PrintError=>1,AutoCommit=>1});
↓
$dbh=DBI->connect("DBI:mysql:tsumiki;host=localhost;port=/var/lib/mysql/mysql.sock",
"mysql","passwd",{RaiseError=>0,PrintError=>1,AutoCommit=>1});