Ole Tange wrote: > Hi > > I have a couple of time wanted a checksumming filter, > that will work like cat if the input matches the checksum > and output nothing if it does not: > > Get_untrusted_input | > sha256sum bf794518e35d7f1ce3a50b3058c4191bb9401e568fc645d77e10b0f404cf1f22 | > do something on the stream I now know matches the sum. > > Could we extend the *sum programs to support that?
The fact that *sum would need to consume/buffer all the input would mean that the parallelism from the rest of the pipe is lost (well I suppose the process startup overhead is parallelized). I.E. it's functionally equivalent to: Get_untrused_input > /tmp/blah sha256sum -c <(echo "$chksum /tmp/blah") && ... rm /tmp/blah I'm not sure generated input is a common enough usecase to support that directly within sha256sum cheers, Pádraig
