History, export - how and why?

Question

linux

Several situations have arisen, little light has been shed on the Internet, therefore I hope for the help of the Linux / Unix gurus.
1) Why doesn't export like the dot ? Is there any way to shield it?
2) Why are the contents of history and $HISTFILE different?
3) Is it possible to delete several lines in history at once?

Answer 1

1) The dot is escaped with a backslash \
2) Because the standard setting changes $HISTFILE from history at the end of the session, this behavior can be changed by an option, you can read in detail here
3) Enter commands starting with a space and they will not be written to the history. For details on history, click here.