Providing php access to many user require patience plus security aware.
People can damage server with some php function like system, passthru etc.
php provide php.ini file, this file needed to disable some dangerous function.
some option for disable php function are :
system, exec, shell_exec, passthru, set_time_limit, error_log, ini_alter, dl, pfsockopen, openlog, syslog, readlink, symlink, link, leak, fsockopen, popen, escapeshellcmd, apache_child_terminate apache_get_modules, apache_get_version, apache_getenv, apache_note,apache_setenv,virtual
after get this information php must know about these fucntion by editing php.ini files. This file located in C:\windows (in my win xp)
Double click to open, click edit -> find enter "disable_function"
Before edit, the line will like this