When you execute a command, you can instruct history to ignore the command by setting HISTCONTROL to ignorespace AND typing a space in front of the command as shown below. I can see lot of junior sysadmins getting excited about this, as they can hide a command from the history.
It is good to understand how ignorespace works. But, as a best practice, don’t hide purposefully anything from history.
# export HISTCONTROL=ignorespace
# ls –ltr
# pwd
# service httpd stop
[Note: There is a space at the beginning of service, to ignore this command from history]
# history | tail -3
67 ls –ltr
68 pwd
69 history | tail -3