i install bash and keep .bashrc and .bash_history between updates via /etc/sysupgrade.conf, ie
~# grep root /etc/sysupgrade.conf
/root/.screenrc
/root/.bash_history
/root/.bashrc
/root/.ssh/config
# cat .bashrc
# enable basic tab completion in openwrt
bind "set show-all-if-ambiguous on"; bind "set completion-ignore-case on"
# runtime limit of commands in history. default is 500!
export HISTSIZE="5000"
# ignoredups to make the searching more efficient
export HISTCONTROL="ignorespace:ignoredups"
# append, not owerwrite history file (should be set by default, just to make sure)
shopt -s histappend
alias ll='ls -lah --color=tty'
From here, every time you login, run bash and you're good