Execute a command without saving it in the history
It i very useful for hiding your commands which consists of passwords on the commandline.
This is tested in bash shell and works successfully.
Example :
$ echo this goes to history
this goes to history
$ echo this wont go to history
this wont go to history
$ history
1 echo this goes to history
2 history
The manual page of "bash" shows as follows:
HISTCONTROL
A colon-separated list of values controlling how commands are
saved on the history list. If the list of values includes
ignorespace, lines which begin with a space character are not
saved in the history list. A value of ignoredups causes lines
matching the previous history entry to not be saved. A value
of ignoreboth is shorthand for ignorespace and ignoredups. A
value of erasedups causes all previous lines matching the cur‐
rent line to be removed from the history list before that line
is saved. Any value not in the above list is ignored. If
HISTCONTROL is unset, or does not include a valid value, all
lines read by the shell parser are saved on the history list,
subject to the value of HISTIGNORE. The second and subsequent
lines of a multi-line compound command are not tested, and are
added to the history regardless of the value of HISTCONTROL.
Exit without saving history kill -9 $$
this exits bash without saving the history. unlike explicitly disabling the history in some way, this works anywhere, and it works if you decide *after* issuing the command you don't want logged, that you don't want it logged
... $ ( or ${$} ) is the pid of the current bash instance
this also works perfectly in shells that don't have $ if you do something like
kill -9 `readlink /proc/self` 
