Moderators, if this is unacceptable feel free to delete. I just typed it up for CentOs and it is easy for me to paste here as well. More than you wanted to know about sfill and bcwipe. I simply moved the sfill from Kubuntu to CentOs and it runs.
I. I took the file sfill from /usr/bin/sfill in my Kubuntu machine, which I got by sudo apt-get install secure-delete.
I moved it into my CentOs 5.3 machine, also at /usr/bin/sfill using a flash drive, and in su mode, cp to final source.
II. Then, I cloned my emachine, which has several distros on it, to an external HD. I did this with a Puppy Linux live CD, which I booted;
(Of course, I had the USB lead of external HD connected to USB port, and running)
When it booted, I hit F2, then typed:
puppy acpi=off pfix=ram
This loads the Puppy distro solely in Ram so it touches nothing.
A few clicks for keyboard, and when it shows Desktop, if you want change resolution.
Then click on the icon which says console. Enter
dd if=/dev/sda of=/dev/sdb
These are the names Puppy shows on the Desktop.
Wait 16+ hours. Record message on completion in case you must reinstall it from clone.
In my case, it said:
234441648 +0 records in
234441648 +0 records out
If you need to reinstall from clone, reverse the sdb and sda, and set blocks per man dd to that number recorded.
III. I re-booted into CentOs, which is on hda13.
Open a terminal, to su
type
sfill -I -l -l -v /home
This wipes all free space in the partition on which /home is located and only does one pass, filling with random data.
Hit <enter>
It will say creating /home/oooooooo.ooo...
Open another console terminal, type
df <enter> Note the usage.
Wait a couple minutes and hit df again, and you can see the partition filling.
On my partition, it was in 1K blocks:
11227664 7839068 used, 2809056 available 74%
It climbed toward 100%. When it said 100% it actually kept going, because the 100% is rounded up, I guess.
When it hit the end, it lets you know it is done. In a minute, the df will show 74% again.
On mine, it took 17 minutes and 14 seconds for one pass.
IV. This does not wipe slack space, the difference between cluster size and file size. Allegedly, this requires a program from
http://www.jetico.com/download/ which is BCWipe-1.9-3.i386.rpm
I installed it with:
rpm -i BCWipe-1.9-3.i386.rpm
I typed: bcwipe and it gave me the basic nomenclature. There is an option for wiping slack space.
Playing with it, I learned that this command will wipe all slack of unhidden files in the current directory only.
bcwipe -mz -n 60 -S -v *
In the Desktop it reported: Wiped 72KB of file slacks.
Note -n 60 is not needed for -mz since it is single pass.
Changing su console to, or example, /sbin, then run above command wiped 472K of file slacks.
It will not do recursive, only current directory.
Someone on the official forums said this in answer to a question how to clean all slack:
"You can try something like find
<path_here> -type f -exec bcwipe -Smd {} \;
Remember, it will be lenghty operation if you have many files there."
I would not trust a command which said "something like" but I bet there is a way if that isn't correct.
So far no system damage noted. But, I sure feel better with a clone.
REMEMBER TO WIPE YOUR EXTERNAL HARD DISK WHEN YOU ARE DONE, IT HAS THE SAME FREE SPACE YOUR HD DID.
