@utu:

The file /etc/init.d/knoppix-startx is a file with many lines of code. But there is only one long line with startx being issued.
Code:
su -l -c "export STARTUP=$STARTUP ; exec /usr/bin/startx -- vt5 -dpi "$DPI" -br -noreset -nolisten tcp" "$USER" </dev/tty5 >/dev/tty5 2>&1 ; RC="$?"
I changed this line so that the output goes into a log file and to virtual terminal #6 instead of vt #5 since vt #5 is invisible while the Xserver is running.
Code:
su -l -c "export STARTUP=$STARTUP ; exec /usr/bin/startx -- vt5 -dpi "$DPI" -br -noreset -nolisten tcp" "$USER" </dev/tty5 2>&1 | /usr/bin/tee -a /var/log/knoppix-startx-dev-tty5.log >/dev/tty6 ; RC="$?"
I think it is always a good idea to make a backup copy of the file before altering it.