source: MondoRescue/branches/2.04_berlios/mindi/aux-tools/sbin/calc-disk-size

#!/bin/sh

# patched by Doug Nordwall, June 28th 2000, to fix a SCSI disk size
# calculation bug; nice one, Doug! :-)      - HR

CalcDiskSize() {
    local res cylinders sectorsize disksize i curr stub out
    res=`fdisk -l $1 2> /dev/null | grep -i "cylinders of"`
    cylinders=`echo "$res" | cut -d' ' -f5`
    sectorsize=`echo "$res" | cut -d' ' -f7`
    cylindermod=`fdisk -l $1 2> /dev/null | grep -i $1:`; # note colon at end to make sure it's not the /dev/sda# partition info
    cylnum=`echo "$cylindermod" | cut -d' ' -f7`
    predisksize=$(($cylinders*$sectorsize/1024))
    disksize=$(($predisksize*$cylnum/1024)); # this works on larger drives; I imagine it'll work on smaller drives with fewer cylinders...

#echo "cylinders = $cylinders; sectorsize = $sectorsize"
#echo "cylnum = $cylnum"
#echo "predisksize = $predisksize; disksize = $disksize"

    if [ "$disksize" = "" ] ; then
    return 1
    else
    echo "$disksize"
        return 0
    fi
}

# ---------------- main ---------------

if [ "$#" -ne "1" ] || [ "`echo "$1" |grep -x "/dev/[a-z]*"`" = "" ]; then
    LogIt "calc-disk-size <device>" 1
    exit 1
fi

LogIt "calc-disk-size --- starting"
out=`CalcDiskSize $1`
if [ "$out" = "" ] ; then
    echo "-1"
else
    echo "$out"
fi

LogIt "calc-disk-size --- leaving"

exit