Clearing Bash History

[TWPonKubuntu]

This article explains how to clear the bash history file used by most terminal apps.

http://www.techrepublic.com/article/...-bash-history/

This has long been a PITA for me when I get into a long terminal session.

This solved the problem.

[edit] please note there are TWO possible routes for this, depending on whether you have one or more terminal windows open...

[kubicle]

One can unset the HISTFILE environment variable or set it to HISTFILE=/dev/null (you can do this in .bashrc, for example) to prevent history from being saved to disk at all. The history should still be kept in memory for the duration of the shell session, just not not saved to disk after the shell closes. (IMO this is a bit cleaner than using a daily cron job to clear history).

https://www.gnu.org/software/bash/ma...acilities.html

[TWPonKubuntu]

kubicle, That would work, although I do like to keep a couple of commands in the history.

I suppose I could retype them after I have done some heavy terminal sessions that fill up the history, but I'd rather not have to retype them.

I do a daily "apt-get update" and "apt-get dist-upgrade" and it is handy to have those bash commands in the history.

At least with the ability to easily clear history, I now only need to retype commands perhaps once a week.

[Snowhog]

Start using aliases for your most used terminal operations. It's what I do.

[SecretCode]

By contrast, I increase $HISTSIZE and make extensive use of the history (and aliases and script files).

It's such a frustration on Windoze to open a command prompt and try to recall previous commands and get nothing.

[TWPonKubuntu]

Thanks for suggestions on working with bash history, I'll need to play with this for while...

[jlittle]

By contrast, I increase $HISTSIZE and make extensive use of the history...

So do I... I use a different $HISTFILE with each konsole profile with different colours. The set up evolved gradually and these days it's five different history files, 400 items each.

Regards, John Little

[TWPonKubuntu]

John, how do you use 400 entries?

Is there an easy way (gui?) to view and them?

Do you have them in some sort of order or grouping?

[jlittle]

As SecretCode said, set HISTFILE, typically in your .bashrc:
[code ]HISTFILE=400[/code ]
Note that bash instances will use the same file by default, and the last to exit overwrites the other's (unless it's been changed, it's been much requested and zsh does something clever.)

Regards, John Little

[jlittle]

Is there an easy way (gui?) to view and them?

Do you have them in some sort of order or grouping?

No GUI, but I use a program to list the recent history in two columns, older on the right. (on Tapatalk here, or I'd do a screenshot)
The history files are organized by the text colour of the corresponding konsole profile.

Regards, John Little

[TWPonKubuntu]

Which program do you use for two column display?

[GreyGeek]

By contrast, I increase $HISTSIZE and make extensive use of the history (and aliases and script files). ...

I make bash history unlimited. It's part of my "memory"

[jlittle]

Which program do you use for two column display?

Originally I used an alias like

alias h='history $(((LINES-1)*2)) | pr -2 -t -l $((LINES-1)) -w $COLUMNS'

but that put the older column on the left, would mess up if I'd used a multi-line command, or had various control characters, and would waste 6 columns. So I wrote a C programme to get the output I wanted, long ago rewritten in C++. Slightly blurry screenshot:

The history line number colour matches the coloured bash prompt, which varies by konsole profile.

I make bash history unlimited. It's part of my "memory"

I don't do that because the history numbers become quite long, taking up more space on screen, and I use alias r='fc -s' to rerun commands from the history, and long history numbers are a nuisance. Of course, what I should do is move to zsh, but I've never got around to it.

[SecretCode]

John, how do you use 400 entries?

Is there an easy way (gui?) to view and them?

Do you have them in some sort of order or grouping?

gui, not that I know of

history displays them, and by piping to grep you can filter out likely candidates.

Built in to bash is 'reverse-i-search' - press ctrl-r and start typing - the most recent history item that matches (anywhere) will be displayed. Handy.

I add some non-default entries in ~/.inputrc for 'history-search-backward; and 'history-search-forward' - this means you type the first few characters and then you can press the up or down arrow keys and cycle through every command in your history that begins with those characters. Very handy!

"\e[A": history-search-backward
"\e[B": history-search-forward
"\e[1;5A": history-search-backward
"\e[1;5B": history-search-forward
"\e[5~": history-search-backward
"\e[6~": history-search-forward

Left as an exercise for the reader to work out which keys those are.

[SecretCode]

Note that bash instances will use the same file by default, and the last to exit overwrites the other's (unless it's been changed, it's been much requested and zsh does something clever.)

There is a way to get this to work, and I have it working, I just don't know which bit of my .bashrc (which has migrated through many *buntu installations) makes it work.

Some net research suggests:

export PROMPT_COMMAND="history -a; history -c; history -r; $PROMPT_COMMAND"