[SEJeff]

This entire blog post could be reduced to use the HISTFORMAT variable, which the author doesn't apparently know about. Put this in your ~/.bashrc:

    export HISTTIMEFORMAT='%Y-%m-%d %H:%M.%S | '

An example of the "history | tail" results:

    $ history | tail
    50198  2016-05-31 10:15.57 | cd docker
    50199  2016-05-31 10:16.03 | cd rpms/
    50200  2016-05-31 10:16.11 | scp docker* omniscience:/tmp/
    50201  2016-05-31 10:14.06 | screen -ls
    50202  2016-05-31 08:33.34 | screen -x
    50203  2016-05-31 19:06.53 | grep HIST .bashrc
    50204  2016-05-31 19:07.46 | history | tail
    50205  2016-05-31 19:08.10 | task ls
    50206  2016-05-31 19:08.23 | docker ps -qa
    50207  2016-05-31 19:08.30 | history | tail

A few from my bashrc:

    $ grep HIST .bashrc
    HISTCONTROL=ignoredups:ignorespace
    # for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
    export HISTFILESIZE=99999
    export HISTSIZE=99999
    export HISTTIMEFORMAT='%Y-%m-%d %H:%M.%S | '
    export HISTIGNORE="ls:exit:history:[bf]g:jobs"

And then a cronjob that simply backs up the data.

[reptation]

the difference is that the author's version backs up every command to a file as it happens. If you have multiple terminals open, you do not get the same output running "history".

[SEJeff]

something other than:

    shopt -s histappend

Isn't that exactly what that shell option does?

[LukeShu]

That does make multiple terminals play nice with eachother, but it's still different, as OP's still flushes to HISTFILE after every command. But, then we can do that with

    PROMPT_COMMAND='history -a'