GNU sha256sum(1) &tc --check (-c) output depends on order of --quiet and --warn

[Brian Foster]

The output of GNU sha256sum --check (or -c), and related tools (i.e., sha1sum,
sha224sum, sha384sum, and sha512sum) depends on the order of the --quiet and
--warn options. This is counter-intuitive, not documented in the man(1) pages,
and unnecessary.

Simple example:

  1$ date >/tmp/data
  2$ sha256sum /tmp/data >/tmp/sums
  3$ sha256sum -c --warn --quiet /tmp/sums # No output (expected)
  4$ sha256sum -c --quiet --warn /tmp/sums # Unexpected "Ok"...
  /tmp/data: OK
  5$

The manual page says (spurious lines omitted):

   The following five options are useful only when verifying checksums:
     --quiet don't print OK for each successfully verified file
     -w, --warn warn about improperly formatted checksum lines

There is no reason --warn should affect the operation of --quiet (nor
visa-versa). The operations as documented are orthogonal.

Attached is a bash(1) shell script written when puzzling over this
inconsistent behaviour; it may be useful (use --help for a summary).

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: coreutils 8.30-3ubuntu2
ProcVersionSignature: Ubuntu 5.4.0-52.57-generic 5.4.65
Uname: Linux 5.4.0-52-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.10
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
Date: Fri Oct 30 21:34:31 2020
InstallationDate: Installed on 2020-10-19 (11 days ago)
InstallationMedia: Kubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: coreutils
UpgradeStatus: No upgrade log present (probably fresh install)

[Brian Foster (blfoster)]

Obviously, I meant sha256sum(1) in the bug's title! (*sighs*)

[Hans Joachim Desserud (hjd)]

Thanks for taking your time to report this issue and help making Ubuntu better.

I tried the simple example given in the description and got the same, somewhat unexpected result with coreutils 8.32-3ubuntu1 on Ubuntu 20.10. Thus marking confirmed.

By the way, if you click the yellow pencil next to the title, you can update it :)