Você pode conseguir isso com:
# make sure you set the right paths for sdX dd if=/dev/sdX of=~/outputfile bs=512 skip=205266 count=29106280
Explicação das opções:
if= describes the inputfile path of= describes the output file path bs= states the blocksize in bytes skip= skips bs size blocks at the beginning of input file count= read N blocks (so in your case N = (End+1)-Begin)