4 ms·
According to the documentation of dd, "iflag=fullblock" is required only when dd is used with the "count=" option. Otherwise, i.e. when dd has to read the enti
by adrian_b 3y ago
According to the documentation of dd, "iflag=fullblock" is required only when dd is used with the "count=" option.
Otherwise, i.e. when dd has to read the entire input file because there is no "count=" option, "iflag=fullblock" does not have any documented effect.
From "info dd":
"If short reads occur, as could be the case when reading from a pipe for example, ‘iflag=fullblock’ ensures that ‘count=’ counts complete input blocks rather than input read operations."
- tripflag 3y agoThank you for the correction -- it is likely that I did use count= when I ran into this some 10 years ago (and been paranoid about ever since). I thought a chunk of data was missing in the middle of the output file, causing everything after that to be shifted over, but I'm probably misremembering.
- fsckboy 3y agothank you for bringing it up! i wasn't even aware of this potential problem, and I use bs= count= and skip= seek= (sk"i"p means "input") through pipes across the net aaaallll the time for decades. it pretty much seems iflag=fullblock is a requirement if you want the counts to work, even though the failure times might be rare