Pádraig Brady wrote: > On 16th June 2008, Paul Eggert wrote: >> Pádraig Brady <[email protected]> writes: >> >>> 5. I think it would be nice for dd to support reading portions of >>> a file efficiently. As far as I can see it can only do it by reading >>> 1 byte at a time. Perhaps skip_bytes=x and count_bytes=x would >>> be useful additions? >> These also sound like good suggestions. > > I just noticed in the info docs for dd that there > is a method to achieve skip_bytes at least: > > (dd bs=1 skip=123456 count=0 && dd bs=8192) < file
For my reference one could also efficiently achieve count_bytes using the following: bs=8192 skip_bytes=$1 count_bytes=$2 ( dd bs=1 skip=$skip_bytes count=0 dd bs=$bs count=$(($count_bytes / $bs)) dd bs=$(($count_bytes % $bs)) count=1 ) < file Still, supporting those internal to dd would be simpler, more portable and robust. cheers, Pádraig.
