Bug 247295

sha256 (and its cousins) have a -c argument to validate against a given checksum. This works fine on files. Example:

$ echo test > file
$ sha256 file
SHA256 (file) = f2ca1bb6c7e907d06dafe4687e579fce76b37e4e93b7605022da52e6ccc26fd2
$ sha256 -c f2ca1bb6c7e907d06dafe4687e579fce76b37e4e93b7605022da52e6ccc26fd2 file; echo $?
SHA256 (file) = f2ca1bb6c7e907d06dafe4687e579fce76b37e4e93b7605022da52e6ccc26fd2
0
$ sha256 -c dead1bb6c7e907d06dafe4687e579fce76b37e4e93b7605022da52e6ccc26beef file; echo $?
SHA256 (file) = f2ca1bb6c7e907d06dafe4687e579fce76b37e4e93b7605022da52e6ccc26fd2 [ Failed ]
2

However, stdin appears to either be always positive or false positive:

$ cat file | sha256
f2ca1bb6c7e907d06dafe4687e579fce76b37e4e93b7605022da52e6ccc26fd2
$ cat file | sha256 -c f2ca1bb6c7e907d06dafe4687e579fce76b37e4e93b7605022da52e6ccc26fd2; echo $?
0
$ cat file | sha256 -c dead1bb6c7e907d06dafe4687e579fce76b37e4e93b7605022da52e6ccc2beef; echo $?
0

I think that sha256 -c should give an error or warning with stdin since it is not handled properly, or preferably function as expected. It would be easy to be misled by the current behavior.

Please let me know if you need anything else from me. Thank you!