====== BASH - History ======

**history** is used to keep track of all commands that were executed on a Linux machine.

By default, the **history** command stores the last one thousand commands.

----

===== History =====

<code bash>
history
</code>

returns:

<code bash>
    1  vi .config/beets/config.yaml 
    2  beet ls
    3  beet remove
    4  beet import /home/peter/Music
    5  beet ls
    6  vi .config/beets/config.yaml 
    7  beet ls
    8  beet import /home/peter/Music
    9  beet ls
   10  vi .config/beets/config.yaml 
   11  beet import /home/peter/Music
...
</code>

As can be seen the timestamp is not in the output.

----

===== Add timestamp to history =====

<code bash>
export HISTTIMEFORMAT="%F %T "
</code>

  * **%F**:  shows Date in the format ‘YYYY-M-D’ (Year-Month-Day)
  * **%T**:  shows Time in the format ‘HH:MM:S’ (Hour:Minute:Seconds)

----

===== History =====

<code bash>
history
</code>

returns:

<code bash>
    1  2019-12-23 13:02:38 vi .config/beets/config.yaml 
    2  2019-12-23 13:02:38 beet ls
    3  2019-12-23 13:02:38 beet remove
    4  2019-12-23 13:02:38 beet import /home/peter/Music
    5  2019-12-23 13:02:38 beet ls
    6  2019-12-23 13:02:38 vi .config/beets/config.yaml 
    7  2019-12-23 13:02:38 beet ls
    8  2019-12-23 13:02:38 beet import /home/peter/Music
    9  2019-12-23 13:02:38 beet ls
   10  2019-12-23 13:02:38 vi .config/beets/config.yaml 
   11  2019-12-23 13:02:38 beet import /home/peter/Music
...
</code>

----

===== Make “HISTTIMEFORMAT” variable persistent across reboots =====

Add this line to the .bashrc file.

<file bash ~/.bashrc>
...
export HISTTIMEFORMAT="%F %T "
...
</file>

and enable this change:

<code bash>
source  ~/.bashrc
</code>

If you want to enable timestamp in history command for all local users too, then define the variable HISTTIMEFORMAT in /etc/profile file instead of root user’s ~/.bashrc file.