ref: f8e841b65c5e515d1fbaba29bd38ce048d6d4bc3
dir: /sys/lib/dist.old/pc/inst/isext2/
#!/bin/rc
if(! ~ $#* 1) {
echo 'usage: isext2 /dev/sdC0/part' >[1=2]
exit usage
}
cmp -s <{dd -if $1 -bs 1 -count 2 -skip 1080 >[2]/dev/null | xd -b |sed 1q} \
<{echo '0000000 53 ef'}
exit $status