I do actually append to it: PROMPT_COMMAND="__last_exit=\$?;history -a \$MCFLY_HISTORY;mcfly add --exit \$__last_exit --append-to-histfile;history -cr \$MCFLY_

I do actually append to it: PROMPT_COMMAND="__last_exit=\$?;history -a \$MCFLY_HISTORY;mcfly add --exit \$__last_exit --append-to-histfile;history -cr \$MCFLY_HISTORY;${PROMPT_COMMAND}"