Re: shred bug? [was: Unidentified subject!]

[debian-user@howorth.org.uk]

David Christensen <dpchrist@holgerdanske.com> wrote:
> On 2/10/24 16:10, Greg Wooledge wrote:
> > On Sat, Feb 10, 2024 at 04:05:21PM -0800, David Christensen wrote:  
> >> 2024-02-10 16:03:50 dpchrist@laalaa ~
> >> $ shred -s 1K - | wc -c
> >> shred: -: invalid file type
> >> 0
> >>
> >>
> >> It looks like a shred(1) needs a bug report.  
> > 
> > I'm confused what you expected this command to do.  You wanted to
> > "destroy" (by overwriting with random data) a pipe to wc?  What
> > would that even look like?
> > 
> > The basic premise of shred is that it determines the size of the
> > file, then writes data over it, rewinds it, and repeats this a few
> > times. A pipe to a process has no size, and can't be rewound.
> > 
> > Declaring a pipe to be an "invalid file type" for shredding sounds
> > pretty reasonable to me.  
> 
> 
> The documentation is confusing:
> 
> On 2/10/24 16:05, David Christensen wrote:
>  > 2024-02-10 16:03:42 dpchrist@laalaa ~
>  > $ man shred | grep 'If FILE is -'
>  >         If FILE is -, shred standard output.  

Maybe it is unstated but mandatory to use -n 1 as well?
And optionally -s N?
I expect reading the code would tell.

First time I've read the man page properly.
Interesting point about COW filesystems such as btrfs :)