编辑php.ini，找到这行：
disable_functions = scandir,passthru,exec,system,chroot,chgrp,chown,shell_exec,proc_open,proc_get_status,
ini_alter,ini_alter,ini_restore,dl,pfsockopen,openlog,syslog,readlink,symlink,popepassthru,
stream_socket_server,fsocket,fsockopen