Save bash history into separate files based on iTerm2 session id.

.profile_term_session_history

#TODO: support WSL's $WT_SESSION and tmux panes ($TMUX_PANE?)
if [ "$TERM_SESSION_ID" != "" ]; then
  if [ "$HISTFILE" != "" ]; then
    OLD_HISTFILE="$HISTFILE"
  else
    OLD_HISTFILE="~/.bash_history"
  fi

  HISTFILE_DIRECTORY="${HOME}/.histories/bash_histories"
  mkdir -p "$HISTFILE_DIRECTORY"
  HISTFILE="${HISTFILE_DIRECTORY}/bash_history-${TERM_SESSION_ID//:/-}"

  if [ ! -f "$HISTFILE" ]; then
    if [ -f "$OLD_HISTFILE" ]; then
      cp "$OLD_HISTFILE" "$HISTFILE"
    fi
  fi
fi