Re: Re: [gentoo-user] How to shred without deleting /dev/*

Re: Re: [gentoo-user] How to shred without deleting /dev/*

[Michael Kintzios]

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> From:: Renat Golubchyk <ragermany@gmx.net>
> To: gentoo-user@lists.gentoo.org
> Subject: Re: [gentoo-user] How to shred without deleting /dev/*
> Date: Mon, 29 Aug 2005 14:35:28 +0200
> 
> Why was it deleted? Did you run the command as root?

Well, yes because when I run it as a plain user I am denied access:
====================
$ shred -u -v /dev/fd0
shred: /dev/fd0: Permission denied
====================

> What's wrong with good old dd? How about
>   $ dd if=/dev/zero of=/dev/fd0
> You can also use /dev/random if it has to be more secure. For even more
> security run it multiple times in a loop.

There's nothing wrong with dd, but I see no reason to create my own script to extend the basic dd functionality.  I would rather use shred which does everything I want it to do - if only I can avoid the deletion if the device node itself.
-- 
Regards,
Mick

Lycos email has now 300 Megabytes of free storage... Get it now at mail.lycos.co.uk

Re: [gentoo-user] How to shred without deleting /dev/*

[Sergio Polini]

Michael Kintzios:
> There's nothing wrong with dd, but I see no reason to create my own
> script to extend the basic dd functionality.  I would rather use
> shred which does everything I want it to do - if only I can avoid
> the deletion if the device node itself.

Why -u?
>From the man page:

========
Delete FILE(s) if --remove (-u) is specified.  The default is not to
remove  the  files because it is common to operate on device files
like /dev/hda, and those files usually should not be removed.
========

BTW, which is your filesystem? From the man page again:

========
CAUTION:  Note  that  shred  relies  on a very important assumption:
that the filesystem overwrites data in place.  This is the traditional
way to do  things,  but  many  modern filesystem  designs  do  not
satisfy  this  assumption.   The following are examples of
filesystems on which shred is not effective:
 * log-structured or journaled filesystems, such as those
 supplied with AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.)
========

HTH
Sergio



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[gentoo-user] How to shred without deleting /dev/*

[Michael Kintzios]

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Hi All,

I was blanking a floppy but when I ran:
====================
$ shred -u -v /dev/fd0
====================
/dev/fd0 was dully deleted after the shred operation finished.  Rebooting the machine relaunched udev which recreated fd0 (is there another way to avoid having to reboot)?

On the second floppy I thought of avoiding unwittingly deleting the fd0 node so I tried:
====================
$ shred -u -v /dev/fd0/
shred: /dev/fd0/: Not a directory
====================
Or:
====================
$ shred -u -v /dev/fd0/
shred: /dev/fd0/*: Not a directory
====================

Is there a way of shredding a complete floppy (not just a file at a time) without removing the /dev/fd0 node?
-- 
Regards,
Mick

Lycos email has now 300 Megabytes of free storage... Get it now at mail.lycos.co.uk

Re: [gentoo-user] How to shred without deleting /dev/*

[Renat Golubchyk]

Hi!

On Mon, 29 Aug 2005 12:01:07 +0000 (GMT) "Michael Kintzios"
<michaelkintzios@lycos.co.uk> wrote:
> I was blanking a floppy but when I ran:
> ====================
> $ shred -u -v /dev/fd0
> ====================
> /dev/fd0 was dully deleted after the shred operation finished.
> Rebooting the machine relaunched udev which recreated fd0 (is there
> another way to avoid having to reboot)?

Why was it deleted? Did you run the command as root?

> Is there a way of shredding a complete floppy (not just a file at a
> time) without removing the /dev/fd0 node? -- 

What's wrong with good old dd? How about
  $ dd if=/dev/zero of=/dev/fd0
You can also use /dev/random if it has to be more secure. For even more
security run it multiple times in a loop.

Cheers,
Renat

-- 
Probleme kann man niemals mit derselben Denkweise loesen,
durch die sie entstanden sind.
                                              (Einstein)
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Re: [gentoo-user] How to shred without deleting /dev/*

[Jason Cooper]

Michael Kintzios (michaelkintzios@lycos.co.uk) scribbled:
> I was blanking a floppy but when I ran:
> ====================
> $ shred -u -v /dev/fd0
> ====================
> /dev/fd0 was dully deleted after the shred operation finished.  Rebooting the machine relaunched udev which recreated fd0 (is there another way to avoid having to reboot)?
> 
> On the second floppy I thought of avoiding unwittingly deleting the fd0 node so I tried:
> ====================
> $ shred -u -v /dev/fd0/
> shred: /dev/fd0/: Not a directory
> ====================
> Or:
> ====================
> $ shred -u -v /dev/fd0/
> shred: /dev/fd0/*: Not a directory
> ====================
> 
> Is there a way of shredding a complete floppy (not just a file at a time) without removing the /dev/fd0 node?

# man shred

[snip]
       -u, --remove
              truncate and remove file after overwriting

       -v, --verbose
              show progress

       -x, --exact
              do not round file sizes up to the next full block;

              this is the default for non-regular files

       -z, --zero
              add a final overwrite with zeros to hide shredding
[snip]

don't use '-u' on devices.

hth,

cooper.

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Re: [gentoo-user] How to shred without deleting /dev/*

[Chris Cox]

On Monday 29 August 2005 07:01 am, Michael Kintzios wrote:
> Hi All,
>
> I was blanking a floppy but when I ran:
> ====================
> $ shred -u -v /dev/fd0
> ====================
> /dev/fd0 was dully deleted after the shred operation finished.  Rebooting
> the machine relaunched udev which recreated fd0 (is there another way to
> avoid having to reboot)?
>

Very seldom is a reboot requried in Linux. You can always run /sbin/udevstart 
as root which will recreate the device nodes.  

> On the second floppy I thought of avoiding unwittingly deleting the fd0
> node so I tried: ====================
> $ shred -u -v /dev/fd0/
> shred: /dev/fd0/: Not a directory
> ====================
> Or:
> ====================
> $ shred -u -v /dev/fd0/
> shred: /dev/fd0/*: Not a directory
> ====================
>
> Is there a way of shredding a complete floppy (not just a file at a time)
> without removing the /dev/fd0 node?

As for your original question about shred I can't really help since I don't 
use it.  And have no need for floppies anymore either.  Try man shred and see 
what the man pages say.

-- 
Chris
Linux 2.6.12-gentoo-r9 i686 AMD Athlon(tm) XP 
 23:19:33 up  4:38,  5 users,  load average: 1.76, 1.50, 1.46
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