在Debian 7.2的apt-get dist-upgrade之后，pdo.so消失了。我做错了什么？
root@tynix:/usr/lib/php5/20100525# apt-get purge php5-mysql
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
php5-mysql*
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 276 kB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ... 43691 files and directories currently installed.)
Removing php5-mysql ...
Purging configuration files for php5-mysql ...
Processing triggers for libapache2-mod-php5 ...
[ ok nstall [....] Reloading web server config: apache2.
root@tynix:/usr/lib/php5/20100525# apt-get install php5-mysql
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
php5-mysql
0 upgraded, 1 newly installed, 0 to remove and 3 not upgraded.
Need to get 0 B/80.9 kB of archives.
After this operation, 276 kB of additional disk space will be used.
Selecting previously unselected package php5-mysql.
(Reading database ... 43683 files and directories currently installed.)
Unpacking php5-mysql (from .../php5-mysql_5.4.4-14+deb7u5_amd64.deb) ...
Processing triggers for libapache2-mod-php5 ...
[ ok ] Reloading web server config: apache2.
Setting up php5-mysql (5.4.4-14+deb7u5) ...
Creating config file /etc/php5/mods-available/mysql.ini with new version
Creating config file /etc/php5/mods-available/mysqli.ini with new version
Creating config file /etc/php5/mods-available/pdo_mysql.ini with new version
Processing triggers for libapache2-mod-php5 ...
[ ok ] Reloading web server config: apache2.
root@tynix:/usr/lib/php5/20100525# php
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php5/20100525/pdo.so' - /usr/lib/php5/20100525/pdo.so: cannot open shared object file: No such file or directory in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php5/20100525/pdo_mysql.so' - /usr/lib/php5/20100525/pdo_mysql.so: undefined symbol: pdo_parse_params in Unknown on line 0
^C
root@tynix:/usr/lib/php5/20100525# ls /usr/lib/php5/20100525/
gd.so mcrypt.so mysqli.so mysql.so pdo_mysql.so