Bash History

If your anything like me you spend a lot of time at a bash terminal, weather I’m upgrading this very WordPress blog, or any other sites I run I usually do so over an SSH connection.

One thing I come to use quite often is my history. often times I don’t quite recall which switches I used to run a command I may have used yesterday. by typing “history” at the command line I get the past 1000 commands (500 by default on most systems) I ran. while thats a bit much lets say I wanted to recall where I saved the last tar archive I created. a simple “history | grep tar” will show all the lines that contain the word tar.

now for some useful options for how your systems history functions, I kicked my system up to record the last 1000 commands you can adjust this by making some changes to the environment in your personal bash configuration file (~/.bashrc) or in the global bash configuration file (/etc/bash.bashrc).

export HISTCONTROL=ignoreboth
export HISTSIZE=1000

the first line will tell bash to ignore lines that match the last command you ran so if you run ps -awfux 3 times in a row (even if its over a couple hours) it will only record a single instance of that command.

the second line defines the size of the history file, in my case I chose to save the past 1000 lines.

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