The first 2 lines in dd stats have the following format:a+b records inc+d records outWhy 2 numeric values? What does this plus sign mean?It's usually a+0, but sometimes when I use bigger block size, dd prints 0+b records out
What does the two numbers mean respectively in dd's a+b records stats?
dd
It means full blocks of that bs size plus extra blocks with size smaller than the bs.pushd $(mktemp -d)dd if=/dev/zero of=1 bs=64M count=1 # and you get a 1+0dd if=1 of=/dev/null bs=16M # 4+0dd if=1 of=/dev/null bs=20M # 3+1dd if=1 of=/dev/null bs=80M # 0+1_crap=$PWD; popd; rm -rf $_crap; unset _crap# frostschutz's caseyes | dd of=/dev/null bs=64M count=1 # 0+1Edit: frostschutz's answer mentions another case to generate non-full blocks. Worth reading. See also https://unix.stackexchange.com/a/17357/73443.