BASH: Is there a way to automatically save recent lines to my bash history during a period of inactivity?
You can use history command with -a option:
history-a Append the ``new'' history lines (history lines entered since the beginning of the current bash session) to the history file.You can write each and every command to history file at once with a little help of PROMPT_COMMAND function:
PROMPT_COMMANDIf set, the value is executed as a command prior to issuing each primary prompt.So just put this into .bashrc
PROMPT_COMMAND="history -a"