Using "SFILL" How to ???

[wittsend]

Hello,

I need to wipe data on a computer a friend is donating. Previously it had Windows 2000 and I have loaded Ubuntu 8.04 LTS on a full drive sized partition. I need to overwrite the remaining free space where Ubuntu didn't use in the install. I found out about "Sfill" but am CLUELESS to use it.

I don't do "Linux speak" well. To me it is like reading a book upside down in a mirror. So, if some could in a step by step fashion, in simple english tell me what to do and how to do it, it would be greatly appreciated. Assume I know nothing so if I need to get to a certain place please tell me how to get there.

I believe I have Sfill installed (as best I can tell) and I know how to get to the Terminal, but that is about it. I read about being "in the root", but haven't a clue how to get there. Again I only want to overwrite ALL the free space, but not whip the drive of Ubuntu.

Thank you for your time.
Regards, Tom

[unmole]

Try this..Open the terminal and type

sfill mountpoint/

Replacing mountpoint/ with the "address" of the partiton you wish to screw.


P.S. It is not 'being in the root' it is 'becoming root'.
This should help you https://help.ubuntu.com/community/RootSudo

[BkkBonanza]

As long as you give it some path on the physical drive you want to wipe it will work ok. It only needs a "mountpoint" to decide which free space (which partition) you're talking about.

Hence, if you have just one partition mounted for everything you could do like this,

sudo sfill /home

If you have multiple partitions mounted in various places then choose a path on a mounted partition you want to fill.

Note that sfill can take a long time. It basically allocates all free space and starts filling it multiple times and then deletes the whole thing. So don't do stuff that will be busy creating/deleting files while you do this.

If I recall last time I used it you can open another terminal and watch the free space shrink away as it works, using "df -h".

[wittsend]

Thank you both for your assistance. I presume that the perpetually active hard drive light is an indicator that I have been successful.

Tom

[BkkBonanza]

I like to watch it fill...

watch -n 5 df -hm

(ctrl-c if you get tired)

Actually, now that I think of it... if you have a big drive this can be excruciatingly slow. It does some 27+ passes! Nowadays most experts say that so many passes provide no benefit.

If you already started it you can ctrl-c and it will clean exit. Then try,

sudo sfill -lzv /home

This only does 2 passes and a final zero. More sane I think.
And the v causes some info to print out as it goes.

[lordal]

sudo sfill -lzv /home

This only does 2 passes and a final zero. More sane I think.
And the v causes some info to print out as it goes.

According to the sfill Manpage

http://manpages.ubuntu.com/manpages/karmic/man1/sfill.1.html

-l lessens the security. Only two passes are written: one mode with
0xff and a final mode with random values.

-z wipes the last write with zeros instead of random data

so -lz should change the second and final pass from random values to zeros rather than add a third pass.

Therefore I would use,

sudo sfill -lv /home

Hope this helps,

Al