Re: Are We Back to the "Wars" Now ?

Carlos E.R. <robin_lis...@es.invalid> [CE]:
CE> I dd a hard disk partition, compress it, and at the same time
CE> calculate a checksum.
CE>
CE>     mkfifo mdpipe
CE>     dd if=/dev/$1  status=progress  bs=16M | tee mdpipe | pigz -3 > $3.gz &
CE>     md5sum -b mdpipe | tee -a md5checksum_expanded
CE>     wait
CE>     rm mdpipe
CE>     echo "$3" >> md5checksum_expanded


David B Rosen has written the tpipe(1) utility for exactly such cases:

The above steps can be rewritten in a much cleaner way as:

  dd if=/dev/$1  status=progress  bs=16M |
  tpipe "md5sum -b >> md5checksum_expanded" |
  pigz -3 > $3.gz


If tpipe is not available on your system, you can always use the shell's
process substitution feature instead:

  dd if=/dev/$1  status=progress  bs=16M |
  tee >(md5sum -b >> md5checksum_expanded) \
      >(pigz -3 > $3.gz) \
      >/dev/null