Command History

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Every command you type is saved in a history file (~/.bash_history or ~/.zsh_history). Knowing how to use it saves time and aids auditing.

Core Commands

Command	Action
`history`	List all recorded commands with their numbers
`!<number>`	Re-run command by its history number
`!-2`	Re-run the second-most-recent command
`!grep`	Re-run the most recent command starting with `grep`
`!grep:p`	Print that command without running it
`history -c`	Clear the entire history for this session

Shortcut	Action
`CTRL + R`	Reverse incremental search — start typing to find a past command
`CTRL + G`	Exit search mode without running anything

Prefix a command with a space to stop it from being recorded:

 secret-command --password=hunter2

This behavior is controlled by HISTCONTROL:

Value	Effect
`ignorespace`	Skip commands prefixed with a space
`ignoredups`	Skip consecutive duplicate commands
`ignoreboth`	Both of the above

Set it in your shell config (e.g. ~/.zshrc or ~/.bashrc):

HISTCONTROL=ignoreboth

Add timestamps to every history entry so you can audit when commands were run:

HISTTIMEFORMAT="%d/%m/%Y %T "

Example output:

120  22/10/2025 11:04:12 ls -la
121  22/10/2025 11:05:01 ranger

Add this to your shell config to persist it.

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