We can always set time to the commands showed in history command as it will be totally a security measure and can be used for troubleshooting/fingerprinting a security threat.
History command sample output before setting this variable is as below:
466 df -h
467 df
468 exit
469 nfsstat
470 find / -iname *.ppt
Inorder to display date and time of execution along with the commands, use inbuilt variable HISTTIMEFORMAT to set the values as shown below:
#export HISTTIMEFORMAT=’%F %T ‘
where,
%F for setting year/month/day
%T for setting time
Now, if we use the history command we can see the difference. The output will be:
500 2011-03-16 17:06:09 exit
501 2011-03-16 17:06:14 apt-get install tree
502 2011-03-16 17:06:36 tree
503 2011-03-16 17:06:54 man tree
504 2011-03-16 17:07:02 tree -d
505 2011-03-16 17:07:07 tree
This is a temporary setting as once we restart or log out from the machine, the setting will revert back.
Inorder to make the change permanent, just append this variable to .bash_profile for every user:
#echo “export HISTTIMEFORMAT=’%F %T ‘” >> ~/.bash_profile
And to set this value to the new user which are going to be created on the machine, export the setting to /etc/profile file:
#echo “export HISTTIMEFORMAT=’%F %T ‘” >> /etc/profile
