Flush Commands to BASH History Immediately

I cannot take credit for figuring this one out. Original post is here.

TLDR; is to add the following to your ~/.bashrc

export PROMPT_COMMAND='history -a'

Following are the history configs that I use

######################################################################
shopt -s histappend
HISTSIZE=-1
HISTFILESIZE=-1
HISTCONTROL=ignoreboth
HISTTIMEFORMAT="[%F %T] "
export PROMPT_COMMAND='history -a'
######################################################################