Options controlling the history

bang_hist

• enable '!' history expansion

append_history

• when exiting, append history entries to $HISTFILE, rather than replacing the old file; this is the default

extended_history

• save additional info to $HISTFILE

hist_ignore_space

• if the commandline starts with a whitespace, don't add it to history

inc_append_history

• append every single command to $HISTFILE immediately after hitting ENTER.

share_history

• always import new commands from $HISTFILE (see 'inc_append_history' above)