.bash_history duplicates

[Robert Holtzman <holtzm@cox.net>]

I've been going thru a number of bash related web sites looking for the 
way to eliminate duplicates in ~/.bash_history. So far I've turned up

export HISTCONTROL=ignoredups
export HISTCONTROL=erasedups
awk '!x[$0]++' .bash_history > .bash.tmp && mv -f .bash.tmp .bash_history
export HISTCONTROL=ignoreboth

Tried them all in ~/.bashrc one at a time and rerunning .bashrc each time. 
So far no joy. Any pointers and/or sources appreciated.

Thanks.

--
Bob Holtzman
"If you think you're getting free lunch,
 check the price of the beer"