bash Cookbook

Setting Shell History Options

Problem

You’d like more control over your command-line history.

Solution

Set the $HIST* variables and shell options as desired.

Discussion

The $HISTFILESIZE variable sets the number of lines permitted in the $HISTFILE. The default for $HISTSIZE is 500 lines, and $HISTFILE is ~/.bash_history unless you are in POSIX mode, in which case it’s ~/.sh_history. Increasing $HISTSIZE may be useful, and unsetting it causes the $HISTFILE length to be unlimited. Changing $HISTFILE probably isn’t necessary, except that if it is not set or the file is not writable, no history will be written to disk. The $HISTSIZE variable sets the number of lines permitted in the history stack in memory.

$HISTIGNORE and $HISTCONTROL control what goes into your history in the first place. $HISTIGNORE is more flexible since it allows you to specify patterns to decide what command lines to save to the history. $HISTCONTROL is more limited in that it sup-ports only the few keywords listed here (any other value is ignored):

ignorespace

Command lines that begin with a space character are not saved in the history list.

ignoredups

Command lines that match the previous history entry are not saved in the history list.

ignoreboth

Shorthand for both ignorespace and ignoredups.

erasedups

All previous command lines that match the current line are removed from the history list before that line is saved.

If $HISTCONTROL is not set, or does not contain any of these keywords, all commands are saved to the history ...