Linux History: Show Commands with Date & Time

Linux history allows you to show past commands executed in terminal session. However, it does not show the date & time of execution. Sometimes you may need to display commands with date & time in Linux. It helps you search for commands executed on a specific date & time. In this article we will look at how to show commands with date & time.

Linux History: Show Commands with Date & Time

Here are the steps to show commands with date & time. By default, history shows only command number and executed command.

Here is the default output of history.

$ history
  1994  sudo systemctl status apache2
  1995  ls
  1996  cd /var/www/html/
  1997  ls
  1998  cd tech-blog/
  1999  ls
  2000  sudo vim .htaccess

The above history command does not display the date/time at which these commands were executed.

Also read : How to Limit Requests Per IP in Apache

In order to show commands with date & time, we will create an environment variable HISTTIMEFORMAT and add it to bash shell with the following command.

$ echo 'export HISTTIMEFORMAT="%d/%m/%y %T "' >> ~/.bash_profile

In the above command, we have used certain format specifiers to describe the timestamp format for commands.

• %d – Day
• %m – Month
• %y – Year
• %T – Time

You can change them as per your requirement. Whenever you run history command, it looks for the HISTTIMEFORMAT variable to determine the date & time format of displayed commands.

Also read : How to Change XAMPP Apache port

Apply the changes using the following command.

$ . ~/.bash_profile
OR
$ source ~/.bash_profile

Now when you run the history command, it will show the commands with date & time.

$ history
  1994  20/04/21 04:15:32 sudo systemctl status apache2
  1995  20/04/21 04:15:32 ls
  1996  20/04/21 04:15:32 cd /var/www/html/
  1997  20/04/21 04:15:32 ls
  1998  20/04/21 04:15:32 cd tech-blog/
  1999  20/04/21 04:15:32 ls
  2000  20/04/21 04:15:32 sudo vim .htaccess

This is useful because if you want to search for commands executed at a particular date & time, just pass the output of history command to grep command. Here is an example,

$ history | grep "20/04/21 04:23"
  2002  20/04/21 04:23:28 echo 'export HISTTIMEFORMAT="%d/%m/%y %T "' >> ~/.bash_profile
  2005  20/04/21 04:29:36 history | grep "20/04/21 04:23"

Please note: When you run above echo command followed by source command, all previous command’s date time will be set to today’s date and time. But the date and time of subsequent commands will be show correctly. Here is an example.

484  01/07/24 04:16:32 ps aux|grep nginx
  485  01/07/24 04:16:32 sudo nginx -c /home/ubuntu/conf/nginx.conf
  486  01/07/24 04:16:32 ps aux|grep nginx
  487  01/07/24 04:16:32 exit
  488  01/07/24 04:12:42 echo 'export HISTTIMEFORMAT="%d/%m/%y %T "' >> ~/.bash_profile
  489  01/07/24 04:13:44 source ~/.bash_profile
  490  01/07/24 04:13:48 history

This is because history doesn’t keep track of date and time of commands unless you explicitly ask it to. SO it cannot assign a specific date and time for past commands. It can only set it for those commands that are run after exporting HISTTIMEFORMAT variable.

If you want to disable it, then open ~/.bash_profile file and remove the following line from it.

export HISTTIMEFORMAT="%d/%m/%y %T

Save and close the file. Run the following command to apply changes.

$ source ~/.bash_profile

Sometimes you may need to start a new session to see the changes, in case they are not applied to current session.

Also read : How to Use Linux History Command