[flavor8]

And then history -c

[vacri]

... which will clear your entire history, which you probably don't want.

I don't know a shorter way, but to delete one line from history, do 'history', which shows the line numbers, then 'history -d LINE_NUM'.

Or, in bash, prepend the command with a space and it won't go into history.

[akerl_]

Open new terminal -> unset HISTFILE -> do your greping -> close terminal

[fletchowns]

Unless somebody did a ps while your grep was running...

Don't put sensitive stuff in CLI args!

[loqi]

Good point, how about

    grep -f - 10-million-combos.txt
    <password>
    ^D^D

[brianshaler]

Depending on your system and configuration, couldn't you prepend a space to the command to prevent it from being saved into your history?

edit: Looks like vacri mentioned this in a peer comment an hour ago. Whoops!

[nmjohn]

That works if you are using bash, but if you are, for example, using zsh, you would first have to run "setopt histignorespace" which would enable hiding lines prepended with a space in the history (it's off by default).