$HISTCONTROL  –  Control History List

$HISTCONTROL is a colon-separated list of values to control how commands are saved on the history file.

Possible values

• ignorespace: lines which begin with a space are not saved
• ignoredups: lines which match the previous line are not saved
• ignoreboth: shorthand for ignorespace and ignoredups
• erasedups: all previous lines matching the current line are removed from the history

Links

• Bash manual
• $HISTIGNORE