Persistent history across all bash terminals

.bashrc

# this part is used to record persistent bash history across terminals
# check http://eli.thegreenplace.net/2013/06/11/keeping-persistent-history-in-bash/ for details
HISTTIMEFORMAT="%d/%m/%y %T "

log_bash_persistent_history()
{
  [[
    $(history 1) =~ ^\ *[0-9]+\ +([^\ ]+\ [^\ ]+)\ +(.*)$
  ]]
  local date_part="${BASH_REMATCH[1]}"
  local command_part="${BASH_REMATCH[2]}"
  # Uncomment the if statement to avoid repeatedly recording the same
  # command when typed inside a single bash session. YMMV.
  # if [ "$command_part" != "$PERSISTENT_HISTORY_LAST" ]

  # this if statement is needed in case the above if statement isn't used
  # because otherwise, pressing enter will create a duplicate entry
  # for the last command that was input
  if [ "$date_part" != "$PERSISTENT_HISTORY_LAST_MOMENT" ]
  then
    echo $date_part "|" "$command_part" "|" "$(pwd)" >> ~/.persistent_history
    export PERSISTENT_HISTORY_LAST="$command_part"
    export PERSISTENT_HISTORY_LAST_MOMENT="$date_part"
  fi
}

# Stuff to do on PROMPT_COMMAND
run_on_prompt_command()
{
    log_bash_persistent_history
}

PROMPT_COMMAND="run_on_prompt_command"

.persistent_history

25/01/17 11:06:00 | set +x | /Users/myusername
25/01/17 11:06:01 | ls | /Users/myusername
25/01/17 11:09:03 | source ~/.bashrc | /Users/myusername
25/01/17 11:09:10 | source ~/.bashrc | /Users/myusername/work/src/github.com/docker/swarmkit
25/01/17 11:09:12 | source ~/.bashrc | /Users/myusername/work/src/github.com/docker/docker
25/01/17 11:09:13 | source ~/.bashrc | /Users/myusername
25/01/17 11:09:15 | source ~/.bashrc | /Users/myusername/Dropbox
25/01/17 11:09:59 | ls | /Users/myusername/Dropbox
25/01/17 11:10:03 | ls | /Users/myusername