Clear your bash history - foil the snoops.

Message

miunk · Post by **miunk** » Wed Mar 31, 2004 3:34 am

A simple tip from a simple mind. If you clear your web history often you should probably clear your bash history as well. Here's an easy way to do it every time you open a new terminal:

Add

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if [ -f ~/.bash_history ]; then
	rm ~/.bash_history
fi

to ~/.bashrc

where ~ is your home directory.

Unne · Post by **Unne** » Wed Mar 31, 2004 5:55 am

Bash history is quite useful, I wouldn't want to delete it every time I logged off. Mine is chmod 600, so isn't that going to stop people from snooping anyways? Unless you happen not to be the sysadmin of the PC you're using, and are worried what root might see.

tomk · Post by **tomk** » Wed Mar 31, 2004 12:25 pm

You can achieve the same thing by making your .bash_history readable but not writeable:

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chmod 400 ~/.bash_history

You still get a history for each session as bash keeps your current history in memory, but it can't write it when it exits so it's not saved anywhere.

BobDylan · Post by **BobDylan** » Wed Mar 31, 2004 12:38 pm

You can achieve the same thing with

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export HISTFILE=/dev/null

in your .bashrc

odegard · Post by **odegard** » Wed Mar 31, 2004 12:54 pm

I've set my history file to 15000 lines, steadily increased from 5000 etc. etc. I find it a huge resource, maybe I should find a script to cut redundant instances...hm... that's not a bad idea...

alec · Post by **alec** » Wed Mar 31, 2004 2:04 pm

"export HISTCONTROL=ignoredups" will stop bash from caching duplicate lines.

odegard · Post by **odegard** » Thu Apr 01, 2004 4:02 am

Thanks, great tip!

blue.sca · Post by **blue.sca** » Thu Apr 01, 2004 7:42 am

thats the tipp i ever wanted about bash

thx alot

rojaro · Post by **rojaro** » Fri Apr 02, 2004 11:36 am

I usually just do

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ln -sf ~/.bash_history /dev/null

but i think the method mentioned by BobDylan is probably the best

bludger · Post by **bludger** » Fri Apr 02, 2004 5:41 pm

I actually like bash history and security is not a problem for me. I like the ignoredups hint earlier and will give it a go.

I have another related question. When are commands actually written to and read from the history file and is there some way of controlling this? It would be useful to be able to write a command in one terminal and the re-issue the command using Ctrl-R from another terminal.

bludger · Post by **bludger** » Fri Apr 02, 2004 5:58 pm

Again, I write a question and then shortly thereafter find the answer myself.

From "man bash":
To append the history from the active shell to the history file: history -a
To read new entries from the history history file to the active shell: history -n

I also noticed that HISTCONTROL=ignoredups only prevents duplicates when the duplicate commands come one after the other. So if you enter:
command_1
command_2
command_1

they will all appear in the history.

miunk · Post by **miunk** » Fri Apr 02, 2004 7:17 pm

To append the history from the active shell to the history file: history -a
To read new entries from the history history file to the active shell: history -n

I'll test when I get back on my gentoo machine, but I am wondering what exactly this means. I am assuming that it means across multiple terminals for the same user. This would be useful. What would be even more useful (although somewhat of a security concern) would be to share bash history between the "wheel" group users and the root user. So setting up my .bashrc and root's .bashrc with BobDylan's method:

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export HISTFILE=/usr/shared/.bash_history

and running:

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chown root /usr/shared/.bash_history
chgrp wheel /usr/shared/.bash_history
chmod 660 /usr/shared/.bash_history

I could set up a shared bash history, so when this happens:

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user@localhost$ emerge -u world
You are just a user idiot, you need to be root!
user@localhost$ su
Password:  
root@localhost$

BAM! Hit up and there it is.

Any ideas how to do this so that?

1) root can get to "wheel" users bash history.
2) "wheel" users can not get to root's bash history.

Twink · Post by **Twink** » Tue Apr 06, 2004 3:30 am

miunk wrote:
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user@localhost$ emerge -u world
You are just a user idiot, you need to be root!
user@localhost$ su
Password:  
root@localhost$ 
BAM! Hit up and there it is.

Any ideas how to do this so that?

1) root can get to "wheel" users bash history.
2) "wheel" users can not get to root's bash history.

Personally I
alias emerge = 'sudo emerge'
on wheel accounts, dunno if thats the kinda thing you want.

miunk · Post by **miunk** » Tue Apr 06, 2004 11:16 am

That is taking the easy way out.

sudo is the best.

Gentree · Post by **Gentree** » Fri May 07, 2004 12:03 pm

how can I increase the number of lines that I can scroll back in bash?

I'm not on about history here , just the console output so I can look back on error output.

Thx

tomk · Post by **tomk** » Fri May 07, 2004 12:25 pm

Gentree wrote:how can I increase the number of lines that I can scroll back in bash?

AFAIK this isn't controlled by bash, but by your terminal. E.g. in xterm it's controlled by the -sl option, have a look at the man page for your terminal.

Gentree · Post by **Gentree** » Fri May 07, 2004 12:31 pm

Thanks,

I'm talking *console* here , not xterm aterm or whatever under X.

login console :

#bash:

I'm sure there is something to put in .bashrc but the doc is HUGE and I have not found what I need .

Sorry if I was not explicit enough.

Thx.

Darian · Post by **Darian** » Fri May 07, 2004 7:41 pm

Regarding the original topic of history... I like to put this in my .bashrc

export HISTCONTROL=ignorespace

Any time I enter a command that I don't want going into my history I just type a space before the command.

Negated Void · Post by **Negated Void** » Fri May 07, 2004 7:54 pm

Call me the devil, but i like to play on my friend's box (I admin it for him, so i have root pass)

Anyways, i find if you don't want what you're doing in bash to show up in the history, just kill bash to logout..