for the user

history
 1142  cat /tmp/somefile.txt
 1262  vim /tmp/somefile.txt
 1663  ps -ef | grep nginx

export HISTTIMEFORMAT='%F %t'

history
 1142  2017-05-26   cat /tmp/somefile.txt
 1262  2017-05-26   vim /tmp/somefile.txt
 1663  2017-05-26   ps -ef | grep nginx