Accessing previous command line entries

bin · 2018-03-05 08:43

Thought I'd just throw this in as a reminder....

Stuff you enter on the command line is all held in your .bash_history file.

You can access all those old commands by either loading that file in a text editor such as write - or you can use the 'history' command.

Just run history and then you can re-run a command just using copy and paste.

However, used with caution but even cooler, just type ! followed by the command number in the list.

I find this really handy as I merge all my old .bash_history files from wherever, clean out the junk and then make it my current file. That way I have easy access to all sorts of obscure stuff that may still be valid.

Dai_trying · 2018-03-05 09:29

I have a handy tiny little script I use to remove duplicates from my bash_history (I use the terminal a lot) and this simply removes all duplicates and sorts the history file in alphabetical order, it usually only takes a fraction of a second to complete.

#!/bin/bash

cat ~/.bash_history | sort -u >~/new_bash_history
mv ~/new_bash_history ~/.bash_history

As you can see it puts the file through sort with the unique option and then overwrites the old history file with the new one.

Last edited by Dai_trying (2018-03-05 09:30)

bin · 2018-03-05 10:04

That's neat!

Sorting to alphabetical order confuses me as I tend to look for commands grouped around a specific task. For example I'll do a number of tests on backports + no-recommends commands for a package to keep cruft to a minimum - or realise that actually a 'suggested' might have been a good idea and so add it to the command. So, I use

awk '!a[$0]++' .bash_copy > .new_bash_history

Which just cleans out duplicates and leaves the file in original order.

Dai_trying · 2018-03-05 10:21

I've got used to having mine in alphabetical order now as I've been using this script for years but I might try your method and see how I get on, I can see it being useful to keep them in chronological order, thanks for sharing

chris_elvidge · 2018-03-05 12:32

If you want to keep duplicates out of your history, see man bash / HISTCONTROL

Dai_trying · 2018-03-05 15:21

Thanks for that Chris, I did have ignoreboth in my bashrc but I think the better option (for me) is erasedups which I have now added.

Q4OS Forum

#1 2018-03-05 08:43

Accessing previous command line entries

#2 2018-03-05 09:29

Re: Accessing previous command line entries

#3 2018-03-05 10:04

Re: Accessing previous command line entries

#4 2018-03-05 10:21

Re: Accessing previous command line entries

#5 2018-03-05 12:32

Re: Accessing previous command line entries

#6 2018-03-05 15:21

Re: Accessing previous command line entries

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