为什么我用--with-pdo-mysql = shared，mysqlnd构建php后，当我运行“php -m”时，我找不到PDO模块？

when I run php -r "phpinfo();", I can get the following message about PDO thing:

Configure
Command
=>
'./configure'
...
'--with-pdo-odbc=shared,unixODBC,/usr'
'--with-pdo-mysql=shared,mysqlnd'
'--with-pdo-pgsql=shared,/usr'
'--with-pdo-sqlite=shared,/usr'
'--with-pdo-dblib=shared,/usr'
...

but when I run "php -m", I can not find pdo any more, could any one tells me what wrong with it ?