Cross posting my answer from stackoverflow.
Use the following command to do a clear screen instead of merely adding new lines ...
yes that's a 'printf' on the bash prompt.
You will probably want to define an alias though...
alias cls='printf "\033c"'
\033 == \x1B == 27 == ESC
So this becomes
<ESC>c which is the VT100 escape code for resetting the terminal. Here is some more information on terminal escape codes.
Here are a few other ways of doing it...
printf "\ec" #\e is ESC in bash
echo -en "\ec" #thanks @Jonathon Reinhart.
# -e Enable interpretation of of backslash escapes
# -n Do not output a new line
The above does not work on the KDE console (called Konsole) but there is hope! Use the following sequence of commands to clear the screen and the scroll-back buffer...
clear && echo -en "\e[3J"
Or perhaps use the following alias on KDE...
alias cls='clear && echo -en "\e[3J"'
I got the scroll-back clearing command from here.