creating file by 'dd' and erasing it securely

[R.L. Reingard]

Hello Vram

was of good help your last message. thank you.
with that i did start to do a small file of 3MB and could erase it  
afterwards.
then i attempted to create a realy big file of 5GB and could erase it  
successfully too.
creating the big file took a few minutes and erasing this 'free space' on  
the disk took around 2.5 hours.
great.
regards,
René


****


> Am 04.09.2005, 00:04 Uhr, schrieb Vram <lamsokvr at xprt.net>:

> On Sat, 2005-09-03 at 20:16 +0200, R.L. Reingard wrote:
>> Hi Lee,
>> i do want to have a try with the idea of creating a (huge)file and then
>> erase it afterwards so i changed the command to create a small file  
>> first,
>> which i could use for a test.
>> how to understand the outcome?
>> user at ubuntu:~$ dd if=/dev/zero of=/home/user/hugefile bs=1 count='expr
>> 1024 \* 1'
>> dd: ungültige Zahl „expr 1024 \\* 1“
>> user at ubuntu:~$

> try this command:

> dd if=/dev/zero  of=mybig  bs=1024k  count=3

> vram at Aether:~/tmp $ dd if=/dev/zero  of=mybig  bs=1024k  count=3
> 3+0 records in
> 3+0 records out
> 3145728 bytes transferred in 0.018741 seconds (167851988 bytes/sec)

> Result..

> vram at Aether:~/tmp $ ls -l mybig
> -rw-r--r--  1 vram vram  3145728 2005-09-03 15:00 mybig

> Created a file of size   3125727 bytes.......