I'm not awfully clear on what you've done & why, but I believe this is what you're asking for (NB: taken from 12.10 - it should be similar):
ace@ace2:~/src$ sudo head -n 20 /root/.bashrc
# ~/.bashrc: executed by bash(1) for non-login shells.
# see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
# for examples
# If not running interactively, don't do anything
[ -z "$PS1" ] && return
# don't put duplicate lines in the history. See bash(1) for more options
# ... or force ignoredups and ignorespace
# append to the history file, don't overwrite it
shopt -s histappend
# for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
# check the window size after each command and, if necessary,
# update the values of LINES and COLUMNS.