Shell tip: Clear the command history and screen when you log out

by on May 15, 2007 · 17 comments· LAST UPDATED May 15, 2007

in , ,

For security reason you may want to clear the history file and the screen when you hit CTRL+D or type logout command as you don’t want to left content on screen (i..e avoid an information leak). Some Linux distro may clear the screen but others do not clear the screen when you logout.

When a login shell exits, bash reads and executes commands from the file ~/.bash_logout, if it exists. Basically you can use this file as the individual login shell cleanup file, executed when a login shell exits.

There is a simple solution to this problem, open your ~/.bash_logout file:
$ vi ~/.bash_logout
Append any one of the following command:
/usr/bin/clear_console
OR
/usr/bin/clear
You can also reset your history by appending following commands:
>~/.bash_history
>~/.mysql_history
sync;

First one will clear bash history and 2nd command will clear mysql command history using shell REDIRECTION operator >.

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{ 17 comments… read them below or add one }

1 dbr May 15, 2007 at 10:12 pm

The >~/.bash_history thing seems a slightly odd way of doing things, why not put “unset HISTFILE” in your .bashrc file, since .bash_logout will be run about the time .bash_history is written, so it may (though probably not) end up wiping the file before it’s written.
Or what I prefer to do, rm .bash_history and then :
ln -s /dev/null .bash_history

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2 J May 16, 2007 at 8:40 am

maybe history -c is an option…

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3 nixCraft May 16, 2007 at 9:40 am

>ln -s /dev/null .bash_history
sounds good idea

>maybe history -c is an option…
never thought of that, good idea :)

Appreciate your posts!

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4 naveenvasireddy May 21, 2007 at 4:56 am

really this is very useful for me

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5 NVRAM May 24, 2007 at 3:19 pm

> maybe history -c is an option…
I like it.

I’ve typically used:
HISTFILE=/do/not/use/$RANDOM/$RANDOM

> why not put “unset HISTFILE” in your .bashrc file, since .bash_logout
> will be run about the time .bash_history is written [snip]

Similar idea, but IIRC I’ve had problems with unsetting the HISTFILE — but that was probably ~15 years ago under Korn shell.

I also tried a touch-then-delete approach in my profile, I think that one worked fine, but the $RANDOM is my default.

Incidentally, I try to always do this for root, since on rare occasions passwords are on the command line.

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6 jeff September 27, 2007 at 6:27 pm

ever heard of kill -9 $$ ?

It logs you out and clear the history.

It seems to kill bash, echo $$ gives you the bash PID

A friend of mine showed me this once, but I never completely get how it works, if someone can explain, please do so…

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7 SHAFE April 2, 2008 at 2:01 pm

This is the Wright and the Best OPtion to clear the command History

history -c

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8 Shankar May 23, 2008 at 4:50 am

Thanks shaff, It works

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9 Harka May 23, 2008 at 12:15 pm

Hi,

history -c will clear the entire bash history.
To only clear the current session history use:
history -r.

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10 erica August 11, 2008 at 10:09 am

you are a genius shafe

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11 Kumar Chetan Sharma November 20, 2008 at 7:49 am

even after running clear or history -c, which I find is the best option to add to ./bash_logout, I can still scroll my putty screen and see what all I have done. Is there any way to completely erase this information.

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12 Vinnie July 15, 2009 at 3:38 pm

Kumar asked about clearing the information from his putty window.

To do so -
1. Right click on the top bar of the putty window
2. A Context menu will appear
3. Select “Clear Scrollback”

This will erase all details of your session from putty’s scrollback buffer.

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13 gnudiego September 7, 2010 at 12:19 am

It seems like .bash_logout doesn’t work in psudo-terminals like gnome-terminal or konsole. Anybody has idea why it doesn’t?

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14 Leila November 29, 2010 at 2:09 pm

gnudiego you are correct, it does not work with gnome-terminal which is installed as a default for linux mint. I am considering removing the gnome-terminal but would like to know what the best alternative would be.

Thanks.

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15 Phissure August 18, 2011 at 5:15 pm

I placed “history -r” in .bash_logout

I then added the following to .bashrc, just in case something did get written to .bash_history. It checks if you have any other sessions open, if you don’t it clears the .bash_history file.

if [ w | grep -c $(whoami) = 1 ]; then
>/home/$(whoami)/.bash_history
fi

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16 Ken Mos September 19, 2011 at 1:08 pm

Please update me with putty

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17 My August 19, 2012 at 12:17 am

Harka – You are The man!

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