This post aims to describe some useful bash history settings, that are all too often unknown of. Following are some environment variables described, which can be set in the users bashrc file in eg. ~/.bashrc.


Setting Behaviour
ignorespace Do not record if line starts with a blank/space
ignoredups Do not record line if its a duplicate of the previous line
ignoreboth Do ignorespace and ignoredups
erasedups Do remove all occurences of line before saving line

The settings can be combined by colons, eg. ignorespace:erasedups.

Example: HISTCONTROL="ignorespace:ignoredups"


A colon : separated list of patterns. Patterns may include special * and & characters. * is a wildcard match, please note that matching a whole line is not implied at the end of your patterns. You must explicitly set *. & matches the previous line in the history. Escaping can be done via double backslashes, eg \\&.

Example: HISTIGNORE=cd *:ls *:&


The amount of lines to save in the history. This defaults to 500.

Example: HISTSIZE=1000000


The path where the history is stored. Defaults to ~/.bash_history.

Example: HISTFILE=/dev/null

Condensing the History

My favorite history setting is to condense the history instead of using it as a log of consecutive commands. Save to ~/.bashrc or system-wide in /etc/bash/bashrc

HISTIGNORE='cd *:ls *'

Deactivating the History

Some hackers use this trick to not get commands logged.

export HISTFILE=/dev/null

Useful History Commands and Key Combinations

Command or Combination Description
history -a Append current shell instance in-memory history to the history file
Ctrl-r Reverse search the history. Press enter for execution of command