Re: [Bug-tar] [patch v3] Bug / question in tar

[Tim Kientzle]

On Mar 29, 2014, at 1:00 PM, Paul Eggert <address@hidden> wrote:

> Tim Kientzle wrote:
>> As long as it still reads the input files.
> 
> There is no need to read input files when the input data is not used for 
> anything.  People who want to fool tar into actually reading the files can 
> pipe its output to another program that discards it.

I'm curious.  If someone types the following command:

   tar cf /dev/null some files

What do you think they expect to happen?

I have heard of people using "tar cf /dev/null /mnt/cdrom" to test whether the 
files on a CD-ROM were readable.  If tar "optimizes" by not reading the files, 
that could lead a person relying on this behavior to erroneously believe the 
CD-ROM had no errors.

If you really believe that sending output to /dev/null should not do anything, 
make it a fatal error so people won't rely on it.

Tim