bug#61530: sha256sum check single file in a mutiple sha sum text file

[Bernhard Voelker <mail@bernhard-voelker.de>]

tag 61530 notabug
close 61530
stop

On 2/15/23 14:28, Andreas Löw wrote:
>     Hello,
> 
>     I want to check a single file for correct sha256. All the files of my
>     directory are included in a sha256 text file named allsha256.
> 
>     The sha256sum always checks all files included in the allsha256 file,
>     even if I write:
> 
>     sha256sum myfile -c allsha256
> 
>     It reports a warning 'no correct formatted line was found for myfile'
>     and later it reports 'myfile OK'
> 
>     Regards,
>     Andreas

The *sum utilities always check all files given in a checksum file(s).
That means once you've passed the -c option, the utility will treat all
further arguments as the name of files with checksums - no matter if the
file appears before or after the -c option:

   $ sha256sum README NEWS    > checksum1
   $ sha256sum TODO configure > checksum2
   $ sha256sum checksum1 -c checksum2
   README: OK
   NEWS: OK
   TODO: OK
   configure: OK

To achieve what you want, you have to pass only the checksum line of the
file you want, e.g.:

   $ grep myfile allsha256s | sha256sum -c -
   myfile: OK

Therefore, I'm hereby marking this as not-a-bug in our bug tracker.

Have a nice day,
Berny