If you must have an Apache2 webserver which is not buffering (realtime printf) transaction, you must remove ‘deflate‘ :
root@plop~# a2dismod deflate Module deflate disabled. Run '/etc/init.d/apache2 restart' to activate new configuration! root@plop~# /etc/init.d/apache2 restart Restarting web server: apache2 ... waiting . root@plop~#