Notes
How to avoid duplicates in bash history
$ echo 'export HISTCONTROL=ignoredups' >> ~/.bashrc
to avoid both duplicates and leading spaces use
$ echo 'export HISTCONTROL=ignoreboth' >> ~/.bashrc
$ echo 'export HISTCONTROL=ignoredups' >> ~/.bashrc
to avoid both duplicates and leading spaces use
$ echo 'export HISTCONTROL=ignoreboth' >> ~/.bashrc