By setting a certain bash environment variable, you can limit which commands are kept in the .bash_history file. The following options can be passed to the HISTCONTROL environmental variable:
ignorespace - omits commands beginning with a space
ignoredups - omits commands that match the previously run command
ignoreboth - combines ignorespace and ignoredups
erasedups - removes previous lines that match the line that was just run
To set it, simply run the following from the command line, or add it to the .bashrc or a single user's .bash_profile:
export HISTCONTROL=ignorespace
If no value is set, then all commands will be saved regardless of their content.
even better:
export HISTFILE=/dev/null
Nothing says "propritary one-liners" like writing history to /dev/null!
Sorry about resurrecting a two-year old post, but the information in it does not match my experience.
I've found that HISTCONTROL only modifies what appears when using the up and down keys.
If you want to omit commands from the shell history file, you can use the HISTIGNORE variable. For example, the following line in your profile will not save (consecutive) duplicates, commands starting with a space, or the 'exit' command in your shell history:
export HISTIGNORE="&: *:exit"